Daily Compound Interest Calculator

This calculator is pre-set to daily compounding (n = 365) — the frequency used by most high-yield savings accounts and money market accounts. You can switch to any other frequency in the dropdown to compare.

What Is Daily Compounding?

Daily compounding means interest is calculated and added to your balance 365 times per year (366 in leap years). Each day's interest is based on the previous day's total balance — principal plus all accumulated interest.

The daily compound interest formula uses n = 365 in the standard formula:

A = P(1 + r/365)^365t

r/365: Daily interest rate (e.g. 5%/365 = 0.01370%/day)
365t: Total number of days

Daily vs Monthly vs Annual Compounding: Real Numbers

The difference between daily and monthly compounding is surprisingly small at typical savings rates. The real win is moving from annual to monthly — not from monthly to daily.

Frequency	$10k after 10 yrs @ 5%	$10k after 30 yrs @ 5%
Annual	$16,288.95	$43,219.42
Monthly	$16,470.09	$44,677.44
Daily	$16,486.65	$44,812.26
Continuous	$16,487.21	$44,816.89
Daily vs Monthly: $16.56 more after 10 years. Monthly vs Annual: $181.14 more.

Bottom line on daily compounding

Banks that advertise "daily compounding" are essentially offering the best compounding possible — continuous compounding adds only fractions of a dollar more. Focus on maximizing APY rather than chasing daily vs monthly compounding.

Which Accounts Compound Daily?

High-yield savings accounts — virtually all online HYSAs compound daily and credit monthly
Money market accounts — typically compound daily
Most CDs (Certificates of Deposit) — compound daily, credited at maturity or monthly
Credit cards — compound daily (working against you at 20%+ APR)
Federal student loans — compound daily during and after deferment

Daily Interest Rate Formula

To find your daily earnings on a balance, divide your APY by 365:

Daily Rate = APY ÷ 365

Example: A $50,000 balance at 5% APY earns approximately:
Daily interest = $50,000 × (0.05 / 365) = $6.85 per day — roughly $2,500/year.

Frequently Asked Questions

In practice, no. On a $10,000 balance at 5% for 10 years, daily compounding earns about $16.56 more than monthly compounding — that's $1.66 per year. The APY already captures the compounding effect, so comparing APYs directly is the right approach when choosing accounts.

Most do, but not all. Some compound monthly. The easiest way to check is to look at the APR vs APY: if APY > APR, the account is compounding (the difference reflects compounding). If they're the same, it's likely compounding annually or there's simple interest.

Use your monthly rate: if APY is 5%, your approximate monthly rate is (1 + 0.05)^(1/12) − 1 ≈ 0.407%. So a $10,000 balance earns about $40.74 in one month. Our calculator shows this precisely in the Year 1 row of the breakdown table.

Daily Compound Interest Calculator