Daily Compound Interest Calculator
Calculate how savings grow when interest is added every day. Include recurring deposits, view your effective annual rate, and see your year-by-year balance with calculation steps.
Enter your details
Interest compounds daily using a nominal annual rate divided by 365.
Beginning: first contribution on the start date. End: first contribution at the next scheduled period boundary.
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Projected results
Estimates only. Taxes, fees and inflation are not included.
Step-by-step calculation
See how the annual rate becomes a daily rate and how daily interest adds to your balance.
Balance growth chart
Deposits Interest
Each bar shows a projected year-end or partial-year balance.
Year-by-year breakdown
| Period ending | Opening balance | Added deposits | Interest earned | Ending balance |
|---|---|---|---|---|
| Calculate to see your schedule. | ||||
What Is Daily Compound Interest?
Daily compound interest is interest that is added to an account balance every day. Once that day’s interest is added, it becomes part of the balance that earns interest on the following day. This creates growth on both the original amount and earlier interest. The effect can be small over a few days but becomes more noticeable over longer periods.
This calculator helps estimate savings growth using a starting amount, annual interest rate, duration and optional contributions. It assumes interest is added daily at a fixed rate. Actual financial products may calculate and credit interest differently.
Daily Compound Interest Formula
In this formula, A is the final amount, P is the initial principal, r is the annual interest rate as a decimal, and d is the number of compounding days. This formula applies when no additional deposits or withdrawals are made.
How to Calculate Daily Compound Interest
Start with an initial balance of $10,000 and a nominal annual interest rate of 5%. Convert the annual rate into a decimal by dividing 5 by 100. Divide that value by 365 to find the daily rate. Multiply the balance by the daily rate to find the first day’s interest.
Add that interest to the existing balance. On the second day, calculate interest on the new balance. Repeat for each calendar day. After 365 days, the ending balance is approximately $10,512.67, with approximately $512.67 in interest, assuming no extra deposits, fees or withdrawals.
Daily Compounding With Monthly Contributions
When you make recurring contributions, every deposit begins earning interest from the date it enters your account. A contribution made earlier generally has more time to grow. This calculator lets you choose daily, weekly, monthly or yearly contributions and specify whether payments happen at the beginning or end of each period.
Each day’s interest is calculated using the current balance. This method handles contributions at different dates without treating all deposits as though they were invested on the first day.
Daily vs. Monthly Compound Interest
Daily compounding adds interest more frequently than monthly compounding. If two products have the same nominal annual interest rate, daily compounding generally produces a slightly higher effective return. The difference becomes more noticeable as balances, rates and time periods increase.
However, an advertised annual percentage yield already reflects compounding. Comparing products with identical APYs is different from comparing products with identical nominal rates.
Effective Annual Rate Explained
The effective annual rate represents the percentage increase from daily compounding over 365 periods without contributions. It can help compare different compounding frequencies. It should not be confused with a personal return that includes additional deposits made throughout the year.
Important Calculation Assumptions
The calculator counts actual calendar days between the start and end dates, including weekends and leap days. It uses 365 as the daily rate divisor throughout the calculation. Interest is retained in the balance, and the internal calculation does not round interest after each day.
The results do not account for changing rates, account fees, taxes, inflation, withdrawals, or different financial institution rules. Always verify important calculations against your financial product’s terms.
Frequently Asked Questions
Does daily compound interest include weekends?
Yes. This calculator includes every calendar day. Actual institutions may apply different rules.
Can I include monthly contributions?
Yes. Enter your contribution amount, choose Monthly, and select beginning or end of period.
Does the calculator use 365 or 366 days?
It always divides the nominal annual rate by 365, while counting actual calendar days in the selected time period.
Are these results guaranteed?
No. They are mathematical estimates using fixed assumptions, not guaranteed financial returns.
Related Finance Calculators
For educational estimates only. Not financial advice.
FREE ONLINE CALCULATOR
Daily Compound Interest Calculator
Change the settings below to calculate your result. You can check the assumptions further down this page.
Balance = initial balance × (1 + annual rate / 365) ^ days.