APY Calculator

How to use

1. 1Pick a calculator mode. Rate to APY converts an advertised rate into the yield you actually earn, APY to rate solves for the rate a bank would have to advertise to deliver a target yield, and Compare offers ranks two accounts side by side.
2. 2Click a deposit account preset (HYSA, CD, money market, checking) to seed a realistic rate and compounding frequency, or type your own values.
3. 3Choose the compounding frequency. Daily and monthly are the most common for US savings and CDs; semi-annual and quarterly are common for bonds and treasuries.
4. 4Optional: add a starting balance and pick a currency to see year-one interest and balance, or in compare mode to see the absolute dollar gap between the two offers.
5. 5Click Copy summary to grab the inputs, APY, basis-point gap, and dollar projection as a plain-text block for a spreadsheet, email, or chat.

About this tool

APY Calculator converts between the nominal annual rate a bank advertises and the Annual Percentage Yield (also called the Effective Annual Rate or Effective Annual Yield) that you actually earn after compounding. The Rate to APY mode takes a nominal rate plus a compounding frequency (annually, semi-annually, quarterly, monthly, semi-monthly, biweekly, weekly, daily on a 360-day or 365-day basis, or continuously) and returns the APY using the standard formula APY = (1 + r / n)^n - 1, with the limiting case APY = e^r - 1 for continuous compounding. Add an optional starting balance and the result panel projects the dollar interest after one year plus the resulting year-one balance, formatted in your choice of US dollar, euro, British pound, Canadian dollar, Australian dollar, Japanese yen, Indian rupee, or Turkish lira through Intl.NumberFormat. The APY to rate mode reverses the calculation: enter a target APY, pick how often the bank compounds, and the tool returns the nominal rate the bank would need to advertise to deliver that yield, using r = n * ((1 + APY)^(1 / n) - 1) or r = ln(1 + APY) under continuous compounding. The Compare offers mode is the one most savers actually want when they are shopping for a high-yield savings account, certificate of deposit, money market account, or treasury alternative: enter two offers with their own rate and compounding frequency, and the tool ranks them by APY, reports the gap in basis points (1 percentage point equals 100 bps), and, if you provide a starting balance, also reports the dollar gap in year-one interest. A spread of even 25 basis points on a five-figure deposit is real money over a year. Common deposit-account presets (high yield savings at 5.00 percent monthly, CDs at 4.75 or 5.25 percent, money market at 3.90 percent, checking at 0.50 percent) seed realistic values in one click. The formula panel shows the exact equations used, the methodology aligns with the Truth in Savings Act (Regulation DD, 12 CFR 1030 Appendix A) APY disclosure rule in the US, and an explainer notes that ledger-driven APY on a real bank statement can differ slightly when the calculation accounts for the exact deposit and withdrawal dates within a period. Everything runs locally; rates, balances, and offers stay in your browser.

Free to use. Works in your browser. No signup, no login.