CD Calculator 2026 — Compare Rates & Compounding (Ally, Marcus, Capital One)

The Formula

The compound interest formula: A = final amount at maturity, P = initial deposit, r = APYThe effective annual rate of return accounting for compound interest. Higher than the nominal interest rate when compounding occurs more than once per year. expressed as a decimal, n = compounding periods per year, t = time in years. More frequent compounding results in more interest earned on interest over the same time period.

Variable Definitions

How to Use This Calculator

1. 1

   Enter your initial deposit amount — CDs typically require a $500 to $5,000 minimum deposit.

2. 2

   Choose the term unit (months or years) and enter the length of the CD term.

3. 3

   Enter the APY offered by the bank (or use the benchmark rates table below as a reference for current market rates).

4. 4

   Select the compounding frequency — daily compounding is most common for high-yield CDs.

5. 5

   Optionally add recurring deposits if your bank allows "add-on" CD contributions.

6. 6

   Review the maturity balance, total principal versus interest breakdown, and effective APY.

Common Applications

• Compare CD offers from different banks by calculating the exact maturity value based on APYThe effective annual rate of return accounting for compound interest. Higher than the nominal interest rate when compounding occurs more than once per year., term length, and compounding frequency.
• Build a CD ladder strategy by modeling how splitting deposits across staggered maturity dates affects overall returns and liquidity.
• Decide between a high-yield savings account and a fixed-term CD by projecting the total interest earned under each option.

CD laddering staggers maturities for regular liquidity access while earning higher long-term rates on most of your deposit

Understanding the Concept

Certificates of Deposit (CDs) offer a guaranteed fixed return in exchange for locking your money away for a predetermined term. The key advantage over regular savings accounts is the higher fixed interest rate that is guaranteed for the entire term. The compounding frequency matters more than most people realize: on a $10,000 1-year CD at 4.25% APYThe effective annual rate of return accounting for compound interest. Higher than the nominal interest rate when compounding occurs more than once per year., daily compounding earns about $8 more than annual compounding — a small but literally free amount. The real strategy for maximizing CD returns is known as "CD laddering": splitting your total deposit across multiple CDs with staggered maturity dates (3-month, 6-month, 1-year, 2-year, etc.) so that some portion of your money matures at regular intervals, giving you ongoing liquidity access while keeping the bulk of your savings earning the higher long-term rates.

Frequently Asked Questions

Sources & References