🪜 CDラダー計算機

複数の定期預金に資金を分散し、満期をずらして運用します。各段の金額、APY、満期額、受取利息に加え、全体の加重平均利回りも確認できます。

総受取利息

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合計利息 — 加重平均 APY — 総満期額 —

段ごとのラダー内訳

段	Amount	APY	Years to Maturity	Maturity Value	Interest Earned

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What Is a CD Ladder and Why Build One?

A CD ladder splits a lump sum across several certificates of deposit with staggered maturity dates instead of locking it all into a single CD term. For example, $25,000 split into five equal $5,000 rungs maturing in 1, 2, 3, 4, and 5 years gives you predictable, recurring access to cash while still capturing the higher yields that longer-term CDs typically pay. As each rung matures, you can either withdraw the funds or reinvest at the current top rate, which is usually the longest available rung. This structure balances two competing goals savers face constant liquidity and maximum yield without forcing an all-or-nothing choice between a low-yield savings account and a multi-year CD that penalizes early withdrawal. Because CD rates generally rise with term length, longer rungs in a ladder should carry a higher APY, and this calculator lets you model that by setting a base rate for the shortest rung and a per-year rate step for each subsequent, longer rung.

How Blended APY Is Calculated

Blended APY (also called weighted average yield) tells you the effective annual return of your entire ladder as if it were one account, rather than looking at each rung in isolation. It is calculated as the sum of each rung dollar amount multiplied by its APY, divided by the total amount invested. When every rung holds an equal dollar amount, as in a standard ladder, the blended APY simplifies to the plain average of the individual rung rates. This number matters because a single headline "top CD rate" advertised by a bank usually applies only to the longest term offered, and it overstates what you actually earn once you account for the lower rates on your shorter, more liquid rungs. Comparing blended APY across different ladder structures (3-rung vs 5-rung, for instance) helps you evaluate the true tradeoff between liquidity and yield.

Choosing the Right Number of Rungs

The number of rungs in your ladder is a tradeoff between simplicity and liquidity granularity. A 3-rung ladder (1, 2, 3 years) is easier to manage and still provides yearly liquidity, making it a good fit for savers with a shorter time horizon or smaller balances where opening five separate accounts feels excessive. A 5-rung ladder (1 through 5 years) captures a wider spread of rates, typically locking in higher yields on the back-end rungs while still offering annual access to a portion of your funds. Some savers also build "mini-ladders" with monthly or quarterly maturities inside a single year for very short-term cash management, though the standard annual-step ladder modeled here (1 through N years) is the most common approach used by banks and credit unions when advertising ladder rate schedules.

CD Ladders vs High-Yield Savings and Treasury Bills

A CD ladder is one of several ways to balance yield and access. High-yield savings accounts offer full liquidity and variable rates that can rise or fall with the Federal Reserve's target rate, while a CD locks in a fixed APY for its term regardless of what rates do afterward, which is valuable if you expect rates to fall. Treasury bills (see our T-Bill Calculator) offer similarly fixed, short-term yields backed by the federal government and are exempt from state and local income tax, an advantage CDs do not share. Many savers combine strategies: keeping an emergency fund in high-yield savings, a CD ladder for medium-term goals with known timelines, and Treasury bills or Series I bonds for additional diversification. Reviewing how each rung of your ladder compares to current T-bill and savings yields before committing funds is a reasonable diligence step.

Early Withdrawal Penalties and Reinvestment Risk

Before building a ladder, understand your bank's early withdrawal penalty (EWP) policy, since breaking a CD before maturity typically forfeits a portion of accrued interest, commonly 90 days of interest for terms under a year and up to 365 days of interest for terms of five years or longer. This calculator assumes each rung is held to full maturity, which is the standard, penalty-free way to realize the maturity values shown. The other major risk is reinvestment risk: when a rung matures, the rate available for a new CD may be lower than what you originally locked in, especially in a falling-rate environment. Laddering partially mitigates this by never having all your money exposed to a single reinvestment decision at once, since only one rung matures at a time.

Are CDs FDIC Insured and How Does Tax Treatment Work?

Certificates of deposit at FDIC-member banks are insured up to $250,000 per depositor, per ownership category, per institution, meaning a CD ladder at a single bank is fully protected as long as your total balance across accounts there stays under that threshold; credit unions offer equivalent NCUA insurance. Interest earned on CDs is taxed as ordinary income in the year it is earned or credited, even if you do not withdraw it, and banks issue a Form 1099-INT for any account earning $10 or more in interest during the year. Because CD interest is fully taxable at your marginal federal (and often state) rate, savers in higher tax brackets sometimes compare after-tax CD yield against tax-advantaged alternatives like Series I bonds, whose interest is exempt from state and local tax (see our I Bond Calculator) or municipal bonds.

Building and Maintaining Your Ladder Over Time

Once your initial ladder matures on schedule, most savers "roll" each maturing rung into a new long-term CD equal to the ladder's longest rung, which keeps the ladder perpetually staggered and captures whatever the current top rate is at each renewal point. For example, in a 5-rung ladder, when the 1-year rung matures, you reinvest it into a new 5-year CD, so the following year another rung matures and the cycle continues indefinitely. This calculator models the initial build-out of the ladder; use it periodically as rates change to re-evaluate whether your base APY and rate-step assumptions still reflect what banks in your area are currently advertising, since CD rates can move meaningfully within a single Fed rate cycle. For a broader view of how your total portfolio return compares once inflation is factored in, our Inflation Calculator and Compound Interest Calculator can help contextualize your real (inflation-adjusted) CD ladder returns alongside other tools like the Mortgage Calculator or Loan Calculator for the rest of your financial plan.

よくある質問

What is a CD ladder in simple terms?

A CD ladder is a savings strategy where you divide your money into several certificates of deposit with different maturity dates, usually spaced one year apart, so that some of your money becomes accessible every year while the rest continues earning a higher, longer-term rate.

この計算機では、各段の APY はどのように決まりますか?

この計算機は簡略化したモデルを使っています。最も短い段（1 年目に満期を迎えるもの）には入力した基準 APY が適用され、以降のより長い各段には、その基準率に年ごとの追加金利ステップを加えた利率が適用されます。基準 APY と金利ステップの両方を、現在あなたの銀行が提示している金利に合わせて調整できます。

ブレンデッド APY とは何ですか。なぜ重要なのですか?

ブレンデッド APY は、ラダー全体の加重平均利回りです。総利息を元本合計で割り、年率換算して算出します。これはラダーの実際の全体リターンを示し、通常は銀行が宣伝する最も高い単一の段の金利より低くなります。

CD を満期前に引き出すとどうなりますか?

多くの CD では、数か月分の利息に相当する早期解約ペナルティが発生し、実際の利回りはここに表示される値より下がります。この計算機は、すべての段をペナルティなしで満期まで保有する前提です。

CD ラダーは FDIC 保険の対象ですか?

はい。FDIC 加盟銀行に預けた CD は、預金者 1 人あたり、所有区分ごと、銀行ごとに最大 250,000 ドルまで保護されます。信用組合では、NCUA による同等の保護が提供されます。

このツールは金融アドバイスですか?

いいえ。この計算機は教育および概算の目的のみであり、金融、投資、税務に関する助言ではありません。実際の銀行金利、複利計算方法、ペナルティ条件は異なります。判断の前に、銀行または認可を受けたファイナンシャルアドバイザーに相談してください。