Daily Compound Interest Calculator: See Growth Day by Day
This daily compound interest calculator shows how a balance could grow over a set number of days when interest compounds daily, monthly, quarterly, or annually. Enter a starting balance, an annual rate, and a number of days to see the ending balance, the interest earned, and the effective annual yield.
Daily Compound Interest Calculator
Ending balance
Under these assumptions, $10,000.00 at a 5.00% rate compounded daily could grow to $10,512.67 after 365 days, including an estimated $512.67 of interest.
- Total interest
- Total contributions
- Effective annual yield
- Daily interest at the start
- Daily interest at the end
Daily vs Monthly vs Annual Compounding
Compounded daily (selected)
$10,512.67$512.67 interest; 5.127% effective yield
Compounded monthly
$10,511.62$511.62 interest; 5.116% effective yield
Compounded annually
$10,500.00$500.00 interest; 5.000% effective yield
Balance Over Time
Balance (solid)Starting balance plus contributions (dashed)
| Period | Through Day | Contributions | Interest | Ending Balance |
|---|---|---|---|---|
| Month 1 | 30 | $0.00 | $41.18 | $10,041.18 |
| Month 2 | 61 | $0.00 | $42.73 | $10,083.91 |
| Month 3 | 91 | $0.00 | $41.52 | $10,125.43 |
| Month 4 | 122 | $0.00 | $43.09 | $10,168.52 |
| Month 5 | 152 | $0.00 | $41.87 | $10,210.39 |
| Month 6 | 183 | $0.00 | $43.45 | $10,253.84 |
| Month 7 | 213 | $0.00 | $42.22 | $10,296.06 |
| Month 8 | 243 | $0.00 | $42.40 | $10,338.46 |
| Month 9 | 274 | $0.00 | $43.99 | $10,382.45 |
| Month 10 | 304 | $0.00 | $42.75 | $10,425.20 |
| Month 11 | 335 | $0.00 | $44.36 | $10,469.56 |
| Month 12 | 365 | $0.00 | $43.11 | $10,512.67 |
Assumptions
- The rate stays constant for the whole period.
- Time is counted as days ÷ 365, and the effect of compounding is spread evenly across each day, so results match A = P(1 + r/n)^(nt) for any number of days.
- Contributions are added at the end of each day, week, or month (a month is 365 ÷ 12 days) and earn interest from that day.
- Fees, taxes, withdrawals, and rate changes are not included.
- Banks may credit interest on different schedules or use a 360-day year, so account statements can differ slightly.
Educational estimate only. This calculator uses the assumptions you enter to illustrate a possible financial outcome. It does not predict future investment performance, interest rates, inflation, taxes, market prices, or financial results. Actual outcomes may differ.
How the Daily Compound Interest Calculator Works
The calculator uses the standard compound interest formula, with time measured in days:
A = P(1 + r/n)^(nt), where t = days ÷ 365
Here P is the starting balance, r is the annual nominal rate as a decimal, and n is the number of compounding periods in a year (365 for daily, 12 for monthly, 4 for quarterly, 1 for annually). Because t can be any number of days, the result works for 30 days, 90 days, or several decades.
Under these assumptions, $10,000 at a 5% rate compounded daily could grow to $10,124.04 after 90 days and $10,512.67 after 365 days. Over 3,650 days, about ten years, it could reach $16,486.65, compared with $16,288.95 if the same rate compounded once a year. These are Fin Loom calculations from the engine that runs this page.
If you add a recurring contribution under Advanced options, each deposit is added at the end of its day, week, or month and starts earning from that day. Adding $100 a month to the same $10,000 at 5% compounded daily could produce about $11,740.54 after 365 days, including an estimated $540.54 of interest, a Fin Loom calculation.
What the Results Mean
Ending balance is the projected total after the last day. Total interest is the growth above the starting balance and contributions. Effective annual yield converts the nominal rate and compounding frequency into one annual figure: 5% compounded daily works out to about 5.127%, and 5% compounded monthly to about 5.116%, both Fin Loom calculations. That is the same idea as annual percentage yield, which the APY calculator explores in more detail.
Daily interest at the start and end shows how much one day of growth adds at the beginning and at the end of the period. On $10,000 at 5% compounded daily, that is about $1.37 on the first day and about $1.44 on the last day of a year, because the balance itself has grown.
The comparison cards run your exact inputs at daily, monthly, and annual compounding side by side. The gap is usually small over short periods and widens as time, rate, and balance increase. The chart traces the balance across every day, and the table breaks the projection into days, months, or years, depending on the length you choose.
Limits of a Daily Compound Interest Calculator
The calculator assumes the rate never changes, which variable-rate savings accounts do not guarantee. It counts a year as 365 days, while some banks use a 360-day year or credit interest on a different schedule, so an account statement can differ by a small amount. Fees, taxes, and withdrawals are not included. For deposit accounts, the bank's disclosed APY, calculated under the CFPB's Regulation DD Appendix A, remains the official comparison figure.
For longer goals that combine a starting balance with regular monthly deposits at a disclosed APY, the savings interest calculator works month by month from the APY instead of from a nominal rate.
More Fin Loom Calculators
This tool is part of Fin Loom's set of financial calculators and reference tools, which covers inflation, compound interest, investment growth, dividends, withdrawals, capital gains tax, and stock trades.
Frequently Asked Questions
How Is Daily Compound Interest Calculated?
It uses A = P(1 + r/n)^(nt) with n = 365 and t = days ÷ 365. Each day's interest is added to the balance, so later interest is earned on earlier interest.
Is Daily Compounding Much Better Than Monthly?
Usually only slightly. At 5%, daily compounding gives an effective yield of about 5.127% versus about 5.116% for monthly, a Fin Loom calculation.
Why Might My Bank's Interest Differ From This Result?
Banks can use a 360-day year, credit interest on their own schedule, change variable rates, or charge fees. The disclosed APY remains the official account figure.