Daily Compound Interest Calculator
Calculate compound interest compounded daily.
See final balance, total interest earned, and a year-by-year breakdown for any principal and rate.
Compound interest is interest earned on top of interest you already earned. Daily compounding adds it to the balance every single day, so tomorrow’s interest is calculated on today’s interest.
The Formula
A = P × (1 + r/n)^(n×t)
Where:
- A = Final balance (what you end up with)
- P = Principal (your starting amount)
- r = Annual interest rate as a decimal (e.g. 5% = 0.05)
- n = Number of compounding periods per year (365 for daily)
- t = Time in years
For daily compounding, n = 365, so the formula becomes:
A = P × (1 + r/365)^(365×t)
Why Daily Compounding Matters
The difference between daily and annual compounding grows larger over time. For example, $10,000 invested at 6% annual interest:
| Years | Annual Compounding | Daily Compounding | Difference |
|---|---|---|---|
| 1 | $10,600 | $10,618 | $18 |
| 5 | $13,382 | $13,498 | $116 |
| 10 | $17,908 | $18,220 | $312 |
| 20 | $32,071 | $33,198 | $1,127 |
| 30 | $57,435 | $60,488 | $3,053 |
Look at the size of that gap honestly, though. Thirty years of daily rather than annual compounding on $10,000 is worth about $3,000, and almost all of the $50,000 the account gained came from the rate and the time, not the frequency. Frequency is the smallest of the three levers.
The Rule of 72
To estimate how long it takes to double your money, divide 72 by your interest rate. At 6%, your money doubles roughly every 72 ÷ 6 = 12 years.
Practical Uses
- High-yield savings accounts, whose rates track the central bank rate and move a lot from year to year
- Certificates of deposit (CDs)
- Money market accounts
- Some bonds and fixed-income instruments
Important Note
This calculator computes growth without additional contributions. For savings with regular deposits, use a compound interest with contributions calculator. Results are for informational purposes only and do not constitute financial advice.
How we build and check this calculator
This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
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