APY Calculator
Turn any stated interest rate and compounding frequency into the APY — the true effective yield — and watch how your savings grow.
A 3.6% rate isn't really 3.6% — compounded daily it yields 3.6654% APY. Always compare accounts by APY, not the headline rate.
3.6654%
APY from a 3.6% rate compounded daily — fed funds via FRED (Q2 2026)
+0.065 pts
extra yield from daily compounding vs the stated rate (Q2 2026)
$1,972
interest earned on $10,000 over 5 years at 3.6654% APY (Q2 2026)
Why APY beats the headline rate
The stated rate is marketing; APY is what actually lands in your account.
APY is the honest number
Two accounts can quote the same interest rate yet pay different amounts if one compounds more often. APY rolls compounding into a single figure — so a 3.6% rate compounded daily becomes a 3.6654% APY you can compare directly.
Compounding stacks interest on interest
Each compounding period adds interest to your balance, and the next period earns interest on that larger balance. More frequent compounding means a slightly higher effective yield — daily edges out monthly, which edges out quarterly.
Time does the heavy lifting
Compounding frequency is a small lever; time is a huge one. $10,000 at 3.6654% APY grows to $11,972 in 5 years — and keeps accelerating the longer you leave it.
How the APY Calculator Works
Formula
APY = (1 + r / n)^n − 1
r = stated annual rate (as a decimal)
n = compounding periods per year (daily 365, monthly 12, quarterly 4, annually 1)
Balance(t) = P · (1 + r / n)^(n · t)
P = deposit, t = yearsEnter your deposit
The amount you're putting into the account.
Enter the stated rate
Defaults to the live federal funds rate (Q2 2026).
Pick a compounding frequency
Daily, monthly, quarterly, or annually.
Set your time horizon
How long the money stays invested.
See your APY and growth
Effective yield, interest earned, and the balance curve.
APY answers a simple question: after a year of compounding, what did I actually earn? Because interest earns interest, the effective yield is always at least as high as the stated rate. In this example, a 3.6% nominal rate compounded daily produces an APY of 3.6654% — a small but real boost of +0.065 percentage points (Q2 2026).
Use APY whenever you shop for high-yield savings accounts, money market accounts, or CDs. It's the standardized figure US banks must publish, so it lets you compare offers fairly. Just remember that real-world rates can change, and interest is generally taxable — this tool models a fixed rate with no withdrawals.