1RM Calculator (One Rep Max)

Safely and accurately calculate your 1RM (One Rep Max), the most important metric in weight training. You can estimate your expected 1RM using only your current weight and repetitions without actually lifting maximum weight, and get appropriate training weights for different intensity levels.

Estimated 1RM (One Rep Max)

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Recommended Weight by Training Intensity

95% — 1-2 reps (Max Strength)

90% — 2-3 reps (Max Strength)

85% — 4-6 reps (Strength)

80% — 6-8 reps (Hypertrophy)

75% — 8-10 reps (Hypertrophy)

70% — 10-12 reps (Endurance)

65% — 12-15 reps (Endurance)

60% — 15+ reps (Warm-up)

※ Epley Formula: 1RM = Weight × (1 + Reps ÷ 30)
※ Accuracy is highest with 1-10 repetitions
※ Results may differ from actual 1RM with more than 10 reps
※ Always test actual 1RM safely with a spotter

GUIDE

Learn more

What is 1RM? Epley vs Brzycki Formula

1RM (One Repetition Maximum) is the maximum weight you can lift for one repetition. It's the most important metric in weight training, providing an objective assessment of your strength level and serving as a baseline for setting training intensity. Epley Formula (1RM = Weight × (1 + Reps ÷ 30)) is the most widely used, with 90-95% accuracy (1-10 reps) and simple, fast calculation. Example: 80kg × 5 reps = 93.3kg. Brzycki Formula (1RM = Weight × (36 / (37 - Reps))) is slightly more conservative than Epley with similar accuracy. Actual 1RM testing is most accurate but carries injury risk, requiring a spotter and complete rest beforehand, limited to 3-5 attempts.

Training Intensity by Goal: Strength, Hypertrophy, Endurance

Maximum Strength (85-100% 1RM): 1-5 reps, 3-5 sets, 3-5 min rest for neural development and pure strength increase. Hypertrophy/Muscle Growth (70-85% 1RM): 6-12 reps, 3-4 sets, 1-2 min rest optimal for bodybuilding. Muscular Endurance (50-70% 1RM): 12-20+ reps, 2-3 sets, 30-90 sec rest effective for endurance and fat loss. Power/Explosiveness (30-60% 1RM): 1-5 explosive reps, 3-5 sets, 3-5 min rest for athletic explosive power. Research shows 1RM-based training improves strength 38% faster than arbitrary weights.

Safe 1RM Testing: Warm-up and Safety Rules

Warm-up Protocol (mandatory): (1) 5-10 min light cardio to increase blood flow, (2) Empty bar 10-15 reps to verify movement pattern, (3) 40% 1RM × 8 reps, (4) 60% 1RM × 5 reps, (5) 80% 1RM × 2-3 reps, (6) 90% 1RM × 1 rep, with 3-5 min adequate rest between sets. Safety Rules: Always have a spotter for max weight attempts (especially bench press asphyxiation risk), stop immediately if form breaks down (safety more important than strength), limit to max 3-5 attempts (excessive attempts cause CNS fatigue), test 1RM once every 4-8 weeks (too frequent causes overtraining), stop immediately for sharp pain/joint sounds/muscle spasms.

Periodization Programs: Linear, Undulating, Block

Linear Periodization (suitable for beginners, systematic progression): Weeks 1-4 Hypertrophy (70-75% 1RM, 8-12 reps) → Weeks 5-8 Strength (80-85% 1RM, 4-6 reps) → Weeks 9-12 Max Strength (90-95% 1RM, 1-3 reps). Undulating Periodization (intermediate+, prevents plateau): Monday Hypertrophy (75% 1RM, 10 reps), Wednesday Strength (85% 1RM, 5 reps), Friday Power (55% 1RM, 3 reps explosive). Block Periodization (advanced, peak performance): Accumulation phase 4 weeks (hypertrophy, volume increase) → Intensification phase 3 weeks (strength, intensity increase) → Realization phase 2 weeks (max strength, volume decrease). Periodization systematically varies training intensity and volume for continuous strength improvement.

Nutrition and Recovery for 1RM Improvement

Protein: 1.6-2.2g per kg bodyweight (70kg = 112-154g/day), consume 20-40g within 30 min post-workout, chicken breast/eggs/fish/whey protein recommended. Carbohydrates: 3-5g per kg bodyweight, complex carbs 1-2 hours pre-workout (sweet potato/brown rice/oatmeal), fast carbs + protein post-workout (banana + protein shake). Hydration: 30-40ml per kg bodyweight (dehydration reduces strength 20-30%). Sleep: 7-9 hours (growth hormone release, muscle recovery). Supplements: Creatine 5g/day (5-15% strength increase proven), caffeine 3-6mg/kg pre-workout (alertness, focus), beta-alanine (muscular endurance improvement).

Practical Application: Progressive Overload and Level-Based Programs

Progressive Overload Principle: (1) Weight increase by 2.5-5kg, (2) Rep increase (80kg × 6 → 8 → 85kg × 6), (3) Set increase (3→4→5 sets), (4) Rest decrease (90→75→60 sec), (5) Slow negatives 3-4 sec, (6) Range of motion increase. Caution: Cannot increase every workout, realistic is 1-2x/week or once every 2-4 weeks. Beginner (6 months): 3x/week full body, focus on Big 3, 70-75% 1RM × 8-12 reps × 3 sets. Intermediate (6 months-2 years): 5x5 Program, 85% 1RM × 5 sets × 5 reps. Advanced (2+ years): Wendler 5/3/1, 4-week cycle (5/3/1 rep structure + deload). Remember: Strength doesn't increase overnight. Consistency and patience are most important!

Frequently asked questions

How is 1RM calculated?

It uses the Epley formula (1RM = Weight × (1 + Reps ÷ 30)). For example, lifting 80 kg for 5 reps gives 80 × (1 + 5/30) ≈ 93.3 kg. Accuracy is highest at 1-10 reps.

Should I test my actual 1RM?

Actual testing is most accurate but carries injury risk. Always warm up thoroughly, use a spotter, limit to 3-5 attempts, and stop immediately if your form breaks down.