How daily compounding works
With daily compounding, your annual rate is split into 365 tiny slices and one slice is applied every day — each day’s interest is calculated on a balance that already includes yesterday’s interest. The formula is the standard compound-interest equation with n = 365:
FV = P × (1 + r/365)365×t
For $10,000 at a 5% nominal annual rate over 10 years, that is 10,000 × (1 + 0.05/365)3650 = $16,486.65. Because interest starts earning interest sooner, daily compounding always beats slower schedules at the same nominal rate — but by less than most people expect.
Daily vs monthly vs quarterly vs annual — same rate, real numbers
$10,000 at a 5% nominal rate, left untouched for 10 years:
| Compounding | Periods/year | Balance after 10 years |
|---|---|---|
| Annually | 1 | $16,288.95 |
| Quarterly | 4 | $16,436.19 |
| Monthly | 12 | $16,470.09 |
| Daily | 365 | $16,486.65 |
Daily beats annual by $197.70 over a full decade, and beats monthly by just $16.55. The lesson: compounding frequency is a tiebreaker between otherwise-identical accounts, not a wealth strategy. A 0.25 percentage point difference in the rate matters more than any frequency upgrade.
Nominal rate vs APY
Because frequency changes the outcome, comparing quoted nominal rates across banks can mislead. The fix is APY (annual percentage yield): the one-year growth including compounding, computed as (1 + r/n)n − 1. A 5% nominal rate is a 5.13% APY compounded daily and a 5.12% APY compounded monthly. When a bank advertises an APY, the compounding is already baked in — enter it here with compounding set to annually and you’ll reproduce the bank’s math.
Fine print worth knowing
- This calculator uses a 365-day year. Some institutions calculate on a 360-day basis, which changes results slightly.
- Many accounts accrue daily but credit monthly — functionally very close to daily compounding.
- Variable-rate accounts change their rate over time; a projection at today’s rate is an estimate, not a promise.
Also try the monthly compound interest calculator, the calculator with monthly contributions, or the full compound interest calculator with all options.
Frequently asked questions
Is daily compounding much better than monthly?
Only slightly, at typical savings rates. $10,000 at a 5% nominal rate for 10 years grows to $16,486.65 with daily compounding versus $16,470.09 with monthly — a difference of $16.55. Frequency matters far less than the rate itself, the amount you contribute, and how long you leave the money invested.
What is the daily compound interest formula?
FV = P × (1 + r/365)^(365×t). Divide the annual rate by 365 to get the daily rate, then compound it once per day. For $10,000 at 5% over 10 years: 10,000 × (1 + 0.05/365)^3650 = $16,486.65.
Do savings accounts really compound daily?
Many high-yield savings accounts calculate interest on the daily balance and credit it monthly, which produces nearly the same result as pure daily compounding. But conventions vary by bank and country — some use monthly compounding, and some products use a 360-day year. Check your account agreement; this calculator uses a 365-day year.
What APY does a 5% daily-compounded rate work out to?
The effective annual yield is (1 + 0.05/365)^365 − 1 ≈ 5.13%. That is the single number that lets you compare accounts with different compounding schedules — the calculator displays it next to the future value for whatever rate you enter.
Educational estimate only — not financial advice. Returns are not guaranteed.