APY Calculator
Convert APR to APY and back, and compare accounts. Runs in your browser.
About this apy calculator
This APY calculator turns an interest rate into an annual percentage yield, the real yearly return once compounding is counted. It also works backwards from an APY to the rate, and it can work out the APY from the interest a bank actually paid you.
Savers use it to compare savings accounts, CDs and money market accounts that quote rates in different ways. Enter a deposit and how long you'll keep it to see the interest in money, and add up to six accounts to compare them side by side.
Every formula is shown with your numbers. The calculator runs in your browser, so nothing about your savings is sent anywhere.
Features
Rate to APY and back
Convert a nominal rate (APR) into APY for yearly to daily or continuous compounding, or turn an advertised APY back into the rate behind it.
APY from interest earned
Enter the starting balance, the interest paid and the days in the term. The calculator applies the US Truth in Savings formula from Regulation DD.
Every compounding at a glance
A table shows the APY of your rate at each compounding frequency, plus a year's interest on your deposit.
Earnings on your deposit
See what a deposit grows to over any number of months, and roughly how much it earns per month in the first year.
Compare up to six accounts
Name each account, enter its rate and compounding, and see each APY and a year's interest. The best one is marked.
How to use the apy calculator
- 1Pick what you know: the rate, the APY, or the interest you earned.
- 2Set the compounding, plus a deposit and how long you'll keep it.
- 3Read the APY or rate, the earnings, and compare up to six accounts.
When to use it
Picking a savings account
One bank quotes 4.40% compounded daily and another 4.50% paid yearly. Put both in the compare list and the APY settles it.
Checking a bank statement
Use the interest-earned mode to confirm the APY a bank paid on a CD or savings account matches what it advertised.
Understanding a credit card's real rate
A card with a 24% APR compounded monthly costs 26.82% a year if you carry a balance. The same formula works for debt.
Projecting savings
Find the APY here, then use the compound interest calculator to add monthly deposits over several years.
How do you calculate APY?
APY = (1 + r/n)^n − 1. Here r is the yearly interest rate as a decimal and n is the number of times interest is added in a year. For continuous compounding it is e^r − 1.
At 5% compounded monthly, APY = (1 + 0.05/12)^12 − 1 = 5.1162%. On 10,000 that's 511.62 of interest in a year instead of the 500 a 5% simple rate would pay.
Going the other way, the rate is r = n × ((1 + APY)^(1/n) − 1). A 5% APY compounded monthly comes from a 4.8889% rate. Compounded daily, it comes from 4.8793%.
APY vs APR: what's the difference?
APR is the yearly rate before compounding. APY includes the effect of compounding, so it's the figure that tells you what you will actually earn in a year. When interest is paid once a year, the two are equal. Otherwise APY is higher.
Banks lean on APY for savings because it's the bigger number, and on APR for loans because it's the smaller one. For loans in the US, APR also includes certain fees, so it is not a pure interest rate either. When you compare, make sure both offers use the same measure.
Does compounding frequency change APY much?
Less than you might think. Here is a 4.5% rate at each frequency:
- Yearly: 4.5000%
- Half-yearly: 4.5506%
- Quarterly: 4.5765%
- Monthly: 4.5940%
- Weekly: 4.6008%
- Daily: 4.6025%
- Continuous: 4.6028%
How banks calculate APY from interest earned
In the US, the Truth in Savings Act and its Regulation DD (12 CFR 1030, Appendix A) set the formula banks must use: APY = 100 × ((1 + Interest ÷ Principal)^(365 ÷ Days in term) − 1). The result is quoted to two decimals.
The regulation's own example is a six-month CD. 1,000 earns 30.37 over 182 days, which gives an APY of 6.18%. Enter those three numbers in the interest-earned mode and you get the same answer. The formula scales a short term up to a full year as if the interest kept compounding at the same pace.
Why use Mavros
| Mavros | Typical upload sites | |
|---|---|---|
| Directions | Rate → APY, APY → rate, and from interest earned | Rate → APY only |
| Regulation DD formula | Yes, with the official example | Not mentioned |
| Compounding table | All seven frequencies side by side | One at a time |
| Account comparison | Up to six, best marked | Single account |
| Formula with your numbers | Yes | No |
| Product offers and ads | None | Common |
Tips
- Compare APY to APY. A higher rate with yearly payouts can lose to a slightly lower rate compounded daily, though the gap is usually tiny.
- Check whether the rate is fixed or variable. Savings account APYs can change at any time; CD rates are locked for the term.
- Look for minimum balances, monthly fees and introductory rates. A fee of 5 a month wipes out the interest on a small balance.
- Interest is usually taxable income. Lower the APY by your tax rate for a rough after-tax figure.
- To see how much more one account pays in percentage terms, the percentage calculator works out the change between two APYs.
Questions
How do you calculate APY?
APY = (1 + r/n)^n − 1, where r is the yearly rate as a decimal and n is the number of compounding periods a year. A 5% rate compounded monthly gives (1 + 0.05/12)^12 − 1 = 5.1162%.
Is APY the same as interest rate?
No. The interest rate leaves out compounding, while APY includes it. They match only when interest is paid once a year. With monthly or daily compounding, APY is always a little higher than the rate.
How much will 10,000 earn at 5% APY?
About 500 in one year, because APY already includes compounding. Over six months it earns about 246.95, since half a year at 5% APY is 1.05^0.5 − 1, or 2.47%.
Is APY calculated monthly?
No. APY is always a yearly figure. The interest may be added monthly or daily, and APY tells you what that adds up to over a full year if you leave the interest in the account.
What is a good APY for a savings account?
It depends on current central bank rates, which change over time. A useful test is to compare against the best rates from several banks this month and against inflation. If APY is below inflation, your money loses buying power.
Why is my APY lower than the advertised one?
Usually because the rate changed, a fee was taken or you added or withdrew money during the period. Regulation DD also rounds interest to the cent before working out the APY, which can shift the last decimal.
What is APY for continuous compounding?
It is e^r − 1. At 4.5% that's 4.6028%, only 0.0003 points more than daily compounding. Continuous compounding is a mathematical limit and rarely used for real savings accounts.
Can I use APY for loans?
You can compute the effective yearly cost the same way, but lenders usually quote APR. For a loan's monthly payment and total interest, the loan EMI calculator is the better tool.