Util Monster Free

🧮 Calculators Collection

Various calculators for daily life and work

Basic Calculators

Basic Calculator

Arithmetic, memory, GT, square root

Scientific Calculator

Trigonometry, logarithm, power, factorial

Math Calculators

Fraction Calculator

Fraction arithmetic and simplification

Percentage Calculator

Percentage, increase, decrease

Percent Error Calculator

Error between measured and actual values

Exponent Calculator

Calculate x to the power of y

ln, log10, any base logarithm

Ratio Calculator

Ratio calculation and simplification

Root Calculator

Calculate nth root

LCM and GCD calculation

GCF and Euclidean algorithm

Factor Calculator

All factors and prime factorization

Rounding Calculator

Round, ceil, floor, truncate

Matrix Calculator

Matrix operations, determinant, inverse

Scientific Notation

Scientific notation conversion

Big Number Calculator

Very large number operations

Quadratic Formula

Solve using quadratic formula

Half Life Calculator

Radioactive decay calculation

Fibonacci Calculator

Fibonacci sequence

Gaussian Elimination

Linear equation solver

Modulo Calculator

Modular arithmetic and cryptography operations

Polynomial Factorization

Factor polynomials

Prime number check & list

Grade point average

Fraction-Decimal Converter

Fraction ↔ decimal

Factorial Calculator

Calculate n! (factorial) exactly using BigInt, for any integer from 0 to 5000. Shows the full digit count and scientific notation.

Pi (π) Digits Calculator

Displays the digits of pi (π) up to 10,000 decimal places, with copy and search (e.g. find your birthday) features.

Collatz Conjecture Calculator (3n+1 Problem)

Enter a starting number to generate the Collatz conjecture (3n+1 problem) sequence — calculates the number of steps to reach 1 and the peak value reached, with a graph.

Riemann Sum Calculator (Definite Integral Approximation)

Enter a function f(x), interval [a,b], and number of subdivisions n to approximate the definite integral using left, right, midpoint, or trapezoidal Riemann sums, with a graph.

Statistics Calculators

Standard Deviation

Standard deviation, variance, mean

Number Sequence

Pattern recognition and prediction

Sample Size Calculator

Survey sample size

Probability Calculator

Probability and conditional probability

Statistics Calculator

Comprehensive statistical analysis

Mean/Median/Mode

Central tendency measures

Permutation & Combination

nPr, nCr calculation

Z-Score Calculator

Z-score and normal distribution

Confidence Interval

Confidence interval and standard error

P-value Calculator

Statistical significance

Rank Calculator

Percentile & rank

Geometry Calculators

Triangle Calculator

Area, perimeter, angle calculation

Volume Calculator

3D shape volume

Slope Calculator

Line slope and equation

Area Calculator

Square Footage Calculator

Calculate room/house area in sq ft, pyeong, or m²

Distance Calculator

Distance between 2D/3D points

Circle Calculator

Circle area, circumference, radius

Surface Area Calculator

3D shape surface area

Pythagorean Theorem

Right triangle side calculation

Right Triangle Calculator

Comprehensive trigonometry

Regular Polygon Calculator

Polygon area, perimeter, angles

Sector Calculator

Sector area, arc length

Pyramid Calculator

Pyramid volume, surface area

Rectangular Prism Calculator

Prism volume, surface area

Rhombus Calculator

Rhombus area, perimeter, angles

Geometry Calculator

Comprehensive geometry

Perimeter Calculator

Shape perimeter

Scale Calculator

Map scale calculation

Finance Calculators

Overspending Index

Income to expense ratio analysis

Discount Calculator

Discounted price and savings

Sales Commission

Commission and net amount

Loss Recovery Calculator

Required gain to recover loss

CAGR Calculator

Compound annual growth rate

Return on investment

ROAS Calculator

Return on ad spend

Depreciation Calculator

Asset depreciation calculation

EBITDA Calculator

Operating cash flow measure

Margin Calculator

Calculate cost, margin rate, and selling price

Appliance Electricity Cost

Calculate electricity bill from wattage and usage time

EV Charging Cost Calculator

Calculate charging cost and savings vs. gasoline vehicles.

Stock Average Price Calculator

Calculate new average price and profit/loss after averaging down.

Stock Profit/Loss Calculator

Calculate realized profit/loss with fees and transaction tax.

Dividend Yield Calculator

Calculate dividend yield or the investment needed for a target income.

Crypto Leverage Liquidation Calculator

Calculate liquidation price and P&L for leveraged long/short positions.

Kelly Criterion Calculator

Calculate optimal bet size from win rate and payout ratio.

Gacha Pity Calculator

Calculate odds and expected cost to reach a pity ceiling.

Martingale Calculator

Simulate bet size and cumulative loss on losing streaks.

Shopify Fee Calculator

Calculate Shopify payment processing fees by plan (Basic/Grow/Advanced/Plus). Supports both Shopify Payments card rates and third-party gateway surcharges.

Amazon FBA Calculator

Enter your Amazon category, sale price, product cost, and FBA fulfillment fee (manual input) to calculate net profit and margin.

eBay Fee Calculator

Enter your eBay category, sale price, and shipping to calculate the final value fee (FVF) and $0.30 per-order fixed fee, and see your net payout.

Etsy Fee Calculator

Enter your Etsy sale price and shipping to calculate the listing fee ($0.20), transaction fee (6.5%), and payment fee (3%+$0.25), and see your net payout.

Stripe Fee Calculator

Calculate the Stripe fee and net payout on a charge, or reverse-calculate what to charge to receive a target net amount. Based on 2.9% + $0.30 (US), with international card surcharge.

PayPal Fee Calculator

Calculate the PayPal fee and net payout on a transaction, or reverse-calculate what to charge to receive a target net amount. Domestic 3.49% + $0.49, with international surcharge.

Wholesale Price Calculator

Calculate wholesale price from cost and target margin, then apply a multiplier (keystone 2x, etc.) to get a recommended retail price.

Baseball Stats

Calculate earned run average from earned runs and innings pitched.

Calculate on-base plus slugging from OBP and SLG.

Slugging Percentage Calculator

Calculate slugging percentage from total bases and at-bats.

WHIP Calculator

Calculate walks plus hits per inning pitched.

Calculate on-base percentage from hits, walks, and HBP.

WAR Calculator (Simplified)

Approximate wins above replacement from plate appearances, OBP, and SLG.

Sports & Fitness

Climbing Grade Converter

Convert climbing difficulty grades between YDS, French, UIAA, and other systems.

Race Time Predictor

Predict your 5K, 10K, half, and full marathon finish times based on a recent race result.

Swim SWOLF Calculator

Calculate your swimming efficiency score (SWOLF) from stroke count and lap time.

Bowling Score Calculator

Calculate your final bowling score including strike and spare bonuses from frame-by-frame pin counts.

Game Sensitivity Converter

Convert mouse sensitivity between different games using DPI and in-game sensitivity settings.

Bike Gear Ratio Calculator

Calculate gear ratio and gain ratio from chainring/sprocket teeth and wheel size.

Tournament Bracket Generator

Generate a single-elimination tournament bracket automatically from your number of participants.

Yoga Pose Hold Timer

Set hold durations for each yoga pose and get guided timing through your sequence.

Cricket Run Rate Calculator

Calculate required run rate (RRR) and projected final score from overs and runs scored.

Tennis Scorekeeper

Track and manage tennis match scores by game and set in real time.

Number Systems

Binary Calculator

Binary conversion and operations

Hexadecimal conversion and operations

Roman Numeral Converter

Convert numbers to/from Roman numerals (1–3,999,999).

Unit Conversion

cm ↔ inch conversion

Pound Converter

lb ↔ kg conversion

mile ↔ km conversion

Ounce Converter

oz ↔ ml conversion

Hectare Converter

ha ↔ pyeong ↔ m² conversion

Temperature Converter

°C, °F, K conversion

Speed-Distance-Time Calculator

Speed, distance, time calc

DMS ↔ decimal conversion

Radian Converter

Radian ↔ degree conversion

acre ↔ m² ↔ pyeong

Gallon Converter

gallon ↔ liter conversion

yard ↔ meter conversion

Horsepower Converter

HP ↔ kW conversion

Vitamin Unit Converter

IU ↔ PPM conversion

Science/Engineering

Density Calculator

Density, mass, volume

Mass Calculator

Mass unit conversion

PPM Concentration

PPM, PPB concentration

Dilution Calculator

Solution dilution

Golden Ratio Calculator

Golden ratio calc

Capacity Calculator

Volume capacity

Resistor Color Code

4-band resistor

Resistor Color Code (5-band)

5-band resistor

Ohm's Law Calculator

Calculate voltage, current, resistance, power via V=IR, P=VI

Parallel Resistor Calculator

Enter multiple resistor values to instantly calculate the equivalent resistance for parallel (1/Rt=Σ1/Ri) or series (Rt=ΣRi) connections. Cross-linked with Ohm's Law and resistor color code calculators.

Torque Unit Converter

Instantly convert torque values between Newton-meters (Nm), foot-pounds (ft-lb), kilogram-force meters (kgf-m), and kilogram-force centimeters (kgf-cm).

Gear Ratio Calculator

Enter driver/driven gear teeth counts and input RPM to calculate gear ratio, output RPM, and torque multiplier. Supports optional 2-stage gear configurations.

Specific Heat Calculator (Q=mcΔT)

Enter any 3 of Heat (Q), Mass (m), Specific Heat (c), and Temperature Change (ΔT) — the calculator derives the missing 1 using Q=mcΔT. Includes a material specific-heat reference table.

Thermal Expansion Calculator (ΔL=αLΔT)

Enter any 3 of Length Change (ΔL), Coefficient (α), Original Length (L), and Temperature Change (ΔT) — the calculator derives the missing 1 using ΔL=αLΔT. Includes a material coefficient reference table.

Reynolds Number Calculator (Re=ρvD/μ)

Enter fluid density (ρ), velocity (v), pipe diameter (D), and viscosity (μ) to compute the Reynolds number (Re=ρvD/μ) and automatically classify the flow as laminar, transitional, or turbulent. Water/air presets included.

Bernoulli Equation Calculator

Enter 5 of the pressure (P), velocity (v), and height (h) values at two points, and this calculator solves for the remaining 1 using Bernoulli's equation.

Heat Transfer Calculator (Conduction & Convection)

Switch between conduction (Q=kAΔT/L) and convection (Q=hAΔT) heat transfer via tabs. Includes thermal conductivity (k) material presets.

Belt Length Calculator

Enter the center distance (C) and diameters (D, d) of two pulleys to automatically calculate the open (non-crossed) belt length.

Pulley System Calculator

Enter the number of rope strands supporting the load (S) and the load weight to instantly get the mechanical advantage (MA=S) and the actual pulling force required.

Hydraulic Cylinder Force Calculator

Enter hydraulic pressure (P) and bore diameter to calculate push force via F=P×A. Pull (retract) force accounts for the rod diameter via the annular area.

Bolt Torque Calculator

Select a metric bolt size (M5-M30) and property class (8.8/10.9/12.9) to look up the recommended tightening torque in Nm and lb-ft from a standard reference table.

Architecture/Real Estate

Building Coverage Ratio

Coverage ratio calc

Floor Area Ratio

FAR calculation

Exclusive Area Calculator

Exclusive/common area

Room Pyeong Calculator

Room size in pyeong

Price per Pyeong

Price per pyeong calc

Tile Installation

Tile quantity needed

Ready-Mix Concrete

Concrete volume

Concrete Calculator

Slab, column, stair volume and cement/sand/gravel quantities

Paint Calculator

Calculate paint amount and cans needed by wall area

Gravel Calculator

Calculate gravel needed (tons/m³) from area and depth

Mulch Calculator

Calculate mulch volume needed for garden beds by area and depth

Air flow calculation

Fractals & Generative Art

Mandelbrot Set Explorer

Explore the Mandelbrot set in your browser. Click to zoom, pan, adjust iterations up to 1000, switch color palettes with smooth coloring, and save your fractal as a PNG.

Julia Set Generator

Generate Julia set fractals in real time. Drag the real and imaginary sliders for the constant c, pick a famous preset, tune iterations, switch palettes, and save a PNG.

Sierpinski Triangle Generator

Draw the Sierpinski triangle by recursive subdivision or watch it emerge from the random chaos game. Adjust depth, points and color, then export a PNG.

L-System Fractal Generator

Generate L-system fractals in your browser. Pick presets like the Koch snowflake or dragon curve, write your own rewrite rules, tune the angle and iterations, and save a PNG.

Voronoi Diagram Generator

Generate colorful Voronoi diagrams in your browser. Every cell holds the region closest to one seed point. Reseed, click to add points, toggle seeds, and save a PNG.

Delaunay Triangulation Generator

Generate a Delaunay triangulation from random or clicked points, with an optional Voronoi overlay. Fill triangles, reseed, and export the result as a PNG.

Spirograph Generator

Create hypotrochoid spirograph patterns from three numbers: ring radius R, gear radius r, and pen offset d. Adjust color and line width, animate, and save a PNG.

Polar Equation Plotter

Plot polar equations r = f(θ) in your browser. Type your own function or pick a rose, cardioid, lemniscate or spiral preset, adjust the theta range and scale, and save a PNG.

3D Surface Plotter

Plot 3D surfaces z = f(x, y) as a rotatable colored mesh. Pick a saddle, ripple or Gaussian preset or type your own function, spin it with sliders, and save a PNG.

Tools

Presentation Timer

Time management

Monitor PPI Calculator

Screen resolution density

Crop Factor Calculator

Camera sensor conversion

Tire size calculation

Tire Aspect Ratio

Tire aspect ratio

Automotive

Stopping Distance Calculator

Calculate total stopping distance from speed, reaction time, and road surface conditions.

Engine Compression Ratio Calculator

Calculate engine compression ratio from cylinder displacement and combustion chamber volume.

Tire Tread Wear Calculator

Calculate tire wear rate and remaining life from tread depth measurements.

Trailer Tongue Weight Calculator

Calculate proper tongue weight from trailer gross weight and load distribution.

Vehicle Weight Distribution Calculator

Calculate front-to-rear weight distribution from axle load measurements.

Headlight Beam Distance Calculator

Calculate headlight beam throw distance from mounting height and aim angle.

Out-the-Door Price Calculator

Calculate the final price of a car including tax, registration, and dealer fees.

Car Affordability Calculator

Calculate how much car you can afford based on your income and monthly payment budget.

Household & Lifestyle

Subscription Cost Tracker

Track and total your monthly and annual spending across multiple subscription services.

Freelance Project Pricing Calculator

Calculate a fair project quote from your hourly rate, estimated hours, and expenses.

Remote Work Savings Calculator

Calculate how much you save by working remotely on commuting, meals, and clothing costs.

Gym vs Home Workout Cost Calculator

Compare gym membership costs against home workout equipment to find the break-even point.

Rent Burden Calculator

Calculate your rent-to-income ratio to assess your housing affordability.

Prorated Rent Calculator

Calculate prorated rent for partial months based on move-in or move-out date.

Rent Increase Calculator

Calculate your new rent and increase amount from the current rent and increase percentage.

Per Diem Calculator

Calculate total travel allowance from trip duration and location-based per diem rates.

Mileage Reimbursement Calculator

Calculate your reimbursement from business miles driven and the per-mile rate.

Gas vs Electric Heating Calculator

Compare fuel costs and efficiency to find which is cheaper: gas or electric heating.

Moving Boxes Calculator

Estimate how many moving boxes you need based on home size and number of rooms.

Storage Unit Size Calculator

Recommend the right self-storage unit size based on the items you plan to store.

Printing Cost Calculator

Calculate document printing costs from paper, ink, and page count.

Tithe Calculator

Automatically calculate a 10% tithe amount from your income.

Zakat Calculator

Calculate your obligatory Islamic charity (Zakat) based on assets and the nisab threshold.

Gross-Up Calculator

Calculate the pre-tax gross payment needed to achieve a target net (after-tax) amount.

Credit Utilization Calculator

Calculate your credit utilization ratio from card limits and outstanding balances.

Betting Odds Converter

Convert between American, decimal, and fractional betting odds and calculate implied probability.

Detergent Dosage Calculator

Enter your laundry weight (kg) and water hardness (soft/medium/hard) to calculate a recommended detergent dose (g/mL) — a general manufacturer-guideline approximation.

Hair Dye Mixing Calculator

Enter your dye amount and desired dye:developer ratio (1:1, 1:1.5, 1:2) to calculate the developer amount and total mixed volume, with a developer-volume reference guide.

Cooking & Kitchen

Marinade Time Calculator

Find the recommended marinating time for chicken, beef, pork, seafood, and tofu/vegetables based on ingredient type and marinade acidity (mild/moderate/strong).

Random Meal Generator

Randomly generate a breakfast, lunch, or dinner idea. Can't decide what to eat? One click settles it.

Smoking Wood Pairing Guide

Find the best smoking wood and flavor intensity for brisket, ribs, chicken, salmon, lamb, sausage, and more.

Spice Substitute Finder

Look up substitutes and recommended ratios for 25+ common spices like cumin, cinnamon, and cardamom — find a stand-in the moment you run out.

Standard Drink Calculator

Enter a drink's volume and ABV to calculate pure alcohol grams and how many standard drinks that equals under US, UK, Australian, Canadian, and Japanese guidelines.

Wine Pairing Recommender

Pick your dish — red meat, seafood, cream pasta, spicy Asian, and more — and get a recommended wine style with the reasoning behind it.

Inventory & Production QA

Contribution Margin Calculator

Calculate contribution margin per unit and the contribution margin ratio from sale price and variable cost, then enter fixed costs to get the break-even sales volume.

Economic Order Quantity (EOQ) Calculator

Enter annual demand, ordering cost per order, and holding cost per unit per year to calculate the Economic Order Quantity (EOQ) and total annual cost.

FIFO/LIFO Inventory Costing Calculator

Enter purchase lots (quantity, unit cost) and units sold to compare FIFO (First-In-First-Out) and LIFO (Last-In-First-Out) cost of goods sold and ending inventory value.

Reorder Point Calculator

Enter average daily demand, average lead time, and safety stock to calculate the reorder point — the inventory level that triggers a new order — using the standard SCM formula.

Safety Stock Calculator

Enter your target service level (Z-score), average lead time, and demand standard deviation to calculate safety stock using the standard SCM formula.

Six Sigma Process Capability (Cp/Cpk) Calculator

Calculate Cp/Cpk process capability indices from spec limits, process mean, and standard deviation, or convert DPMO (defects per million opportunities) to a sigma level.

Working Capital Calculator

Enter current assets and current liabilities to calculate working capital and the current ratio in one step. Quickly check a company's short-term liquidity.

Outdoor & Camping

Backpacking Food Weight Calculator

Calculate total backpacking food weight from trip days, number of people, and activity level, plus a reference daily calorie range.

Knot Tying Guide

Learn 7 essential camping and outdoor knots — bowline, clove hitch, taut-line hitch and more — with uses and step-by-step diagrams.

Naismith Hiking Pace Calculator

Use Naismith's Rule to estimate hiking time from horizontal distance and total ascent.

Tent Footprint Calculator

Calculate the recommended tent floor area by occupancy, or enter tent length × width to get the footprint plus guy-line clearance area.

Crafts & Hobbies

Bead Pattern Calculator

Enter your pattern width/height in beads and your bead size to calculate the total number of beads, grams needed, and a recommended buy quantity with buffer.

Clay Shrinkage Calculator

Work out the greenware (wet clay) size needed for a target fired size, or predict the fired size from your greenware size, using earthenware/stoneware/porcelain shrinkage presets.

Craft Pricing Calculator (Handmade Pricing)

Enter materials cost, hours worked, hourly rate, overhead, and your desired margin rate to calculate a fair sale price and profit for your handmade craft.

Crochet Hook Size Converter (US / UK / mm)

Convert crochet hook sizes between US, UK, and metric (mm). Look up any size instantly with the full standard conversion table.

Cross Stitch Floss (Skein) Calculator

Enter the full cross-stitch count for a color to calculate how many skeins you need. Multiply by number of colors for a rough total-project estimate.

Embroidery Floss Length Calculator

Enter your full cross-stitch count, Aida fabric count, and a waste allowance to calculate the thread length needed, in meters and yards.

Knitting Needle Size Converter (US / UK / mm)

Convert knitting needle sizes between US, UK (old), and metric (mm). Look up any size instantly with the full standard conversion table.

Knitting Gauge Calculator

Enter your gauge (stitches/rows per 10cm) and target size to calculate the stitches and rows needed, plus an estimated yarn amount.

Origami Paper Size Calculator

Enter your desired finished model size (crane, masu box, butterfly, and more) to estimate the required starting paper size, using approximate model-based ratios.

Paint Color Mixing Calculator

Enter R/G/B values to estimate approximate paint mixing proportions (C/M/Y/K %) using the standard RGB-to-CMYK conversion formula. Real paint pigments may vary.

Quilt Binding Calculator

Enter your quilt width and height plus finished binding width to calculate how many strips and how much fabric (in meters and yards) you need for binding.

Resin Casting Volume Calculator

Enter your mold shape and dimensions to calculate the resin volume needed, Part A/B mix amounts, and an estimated weight with overage included.

Pets

Aquarium Heater Wattage Calculator

Calculate recommended heater wattage from tank volume (liters) and desired temperature rise, based on the widely used "3-5 watts per gallon" aquarium-hobbyist rule of thumb.

Birdcage Size Calculator

Choose a bird species and count to see minimum recommended cage size (W×D×H) and bar spacing, based on commonly published aviculture and humane-society guidelines.

Litter Box Count Calculator

Calculate the recommended number of litter boxes from your cat count and number of floors, using the widely cited veterinary-behaviorist "N+1 rule" plus a box-sizing (1.5x body length) guideline.

Pet Air Travel Crate Size Finder

Enter your pet's length, leg height, width, and standing height to calculate the required air-travel crate size and find the nearest standard commercial crate size.

Reptile UVB Calculator

Look up recommended T5 HO UVB tube strength and basking distance range by your reptile's Ferguson Zone. A starting-point reference based on commonly cited reptile-husbandry figures.

Body & Size

Bra Size Calculator

Calculate your US bra size (band + cup) from underbust and bust measurements in cm or inches. Sizing varies by brand — use as an estimate.

Ring Size Converter

Convert ring sizes between US, UK, EU, Japan, and Korea systems, or find your size from inner diameter/circumference in mm.

Steps to Distance Calculator

Convert your step count into distance in kilometers and miles using your height or a custom stride length. Walking and running modes supported.

India Finance

EPF Calculator (India Employees' Provident Fund)

Estimate your India EPF (Employees' Provident Fund) balance at retirement from monthly salary, tenure, and interest rate — using the FY2026-26 rate of 8.25%.

Gratuity Calculator (India)

Calculate your India gratuity payout using the Payment of Gratuity Act's 15/26 formula, based on last drawn salary and years of service.

HRA Exemption Calculator (India)

Calculate your India income-tax HRA (House Rent Allowance) exemption from basic salary, HRA received, rent paid, and metro/non-metro city.

NPS Calculator (India National Pension System)

Estimate your India NPS (National Pension System) retirement corpus, lump sum, and monthly pension from monthly contributions and an assumed return rate.

PPF Calculator (India Public Provident Fund)

Calculate the maturity value and interest earned on India's Public Provident Fund (PPF) over 15 years, using the 2026 rate of 7.1%.

RD Calculator (India Recurring Deposit)

Calculate the maturity value and interest on an India Recurring Deposit (RD) from monthly deposit amount and bank interest rate, using quarterly compounding.

SIP Calculator (India)

Estimate regular, annual step-up, lumpsum, and target SIP scenarios with market-linked assumptions and yearly projections.

SWP Calculator (India Systematic Withdrawal Plan)

Simulate how long your investment corpus lasts under an India SWP (Systematic Withdrawal Plan) with a fixed monthly withdrawal and expected return rate.

Fun

Chinese Gender Predictor

Enter the mother's lunar age and lunar conception month to see the traditional Chinese gender prediction chart result, for fun. No medical or scientific basis.

Love Compatibility Calculator

Enter two names (and optional birthdates) to get a fun love compatibility score. Entertainment only — no scientific basis.

Name Number Calculator

Convert your name into a 1-9 name number using the Pythagorean numerology chart. Entertainment only — no scientific basis.