Daily Compound Interest Calculator
Use this daily compound interest calculator to estimate how money grows when interest is calculated and added to the balance every day. Enter an initial principal, a nominal annual interest rate and an investment duration. The calculator uses a 365-day year and shows the future value, interest earned and effective annual rate instantly, all in your browser.
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Change any value and the results update instantly. Nothing leaves your device.
Currency only changes how amounts are displayed. No amounts are converted between currencies.
Daily compound interest formula.
The calculator uses one formula and one convention for the headline result, the table and the graph.
The formula
A = P × (1 + r/365)^(365×t)Daily interest rate = r ÷ 365. Number of periods = 365 × t. Interest earned = A − P.
Effective annual rate = (1 + r/365)^365 − 1.
What each part means
- A is the future value, the total balance at the end.
- P is the initial principal.
- r is the nominal annual rate as a decimal (7% = 0.07).
- 365 is the assumed number of days in a year and compounding periods per year.
- t is the duration in years.
Why divide by 365?
A nominal annual rate is a yearly figure. Under daily compounding it is split evenly across 365 daily periods, so each day earns r ÷ 365 on the balance at the start of that day. Because each day's interest becomes part of the balance, later days earn interest on earlier interest.
Nominal vs effective rate
The effective annual rate is the growth you actually see over one full year after compounding. It is slightly higher than the nominal rate for any positive rate, because of the daily compounding. At 7% nominal it is about 7.25%.
Interest earned is not the same as future value: future value includes your original principal, interest earned does not.
Worked example.
10,000 at a 7% nominal annual rate for 10 years, compounded daily.
Step by step
- Daily rate: 0.07 ÷ 365 ≈ 0.00019178 (about 0.0192% per day).
- Periods: 365 × 10 = 3,650 daily periods.
- Growth factor: (1.00019178)^3,650 ≈ 2.01362.
- Future value: 10,000 × 2.01362 ≈ 20,136.18.
- Interest earned: 20,136.18 − 10,000 ≈ 10,136.18, a total growth of about 101.36%.
In plain English
10,000 × (1 + 0.07/365)^3,650 ≈ 20,136.18Each day the balance earns one 365th of the annual rate, and that interest is added so it also earns interest the next day. After 10 years the balance has roughly doubled.
The example assumes no extra contributions, no withdrawals, a constant rate and no taxes or fees. For 1 year, the same inputs give about 10,725.01, an effective annual rate of about 7.25%.
What Is a Daily Compound Interest Calculator?
A daily compound interest calculator estimates how much an amount of money could grow when interest is added to the balance every day. You enter the starting amount, a nominal annual interest rate and how long the money stays invested. The calculator then returns the future value, the interest earned and the effective annual rate.
People use a daily compounding calculator to compare savings scenarios, to understand how investment growth over time builds on itself, or simply to check the figures shown in a savings product's description. It is a mathematical model, so it shows what the numbers imply under clear assumptions rather than what any particular account will pay.
What Is Daily Compound Interest?
Compound interest means you earn interest on your original money and on the interest already added. Under a daily compounding model, interest is calculated and added to the balance once per day. Tomorrow's interest is therefore based on a balance that already includes today's interest.
The effect is small from one day to the next but builds over months and years. A longer duration and a higher rate both make the compounding effect larger. Real accounts may credit interest on different schedules or follow their own contractual rules, so this model should be read as an estimate and not as a statement about how a specific bank calculates interest.
How to Use This Daily Compound Interest Calculator
- Initial Principal: the amount you start with. It can be zero, but it cannot be negative.
- Annual Interest Rate: the nominal yearly rate, between 0% and 100%. Enter 7 for 7%. Do not enter the daily rate.
- Investment Duration: between 0 and 100 years. Decimals are allowed, and one year always counts as 365 days.
- Currency format: changes only how amounts are displayed. Nothing is converted between currencies.
The results show the future value (the final balance), the interest earned (future value minus principal), the total growth percentage and the effective annual rate. Open the yearly breakdown to see the balance at the end of each year and how much interest was added during it. The graph plots the same projected balance against the principal.
Daily Compound Interest Formula
The daily compound interest formula is A = P × (1 + r/365)^(365×t). A is the future value, P is the initial principal, r is the nominal annual rate as a decimal and t is the number of years. Dividing r by 365 gives the daily interest rate, and multiplying 365 by t gives the number of daily compounding periods.
It is important to keep the nominal annual rate and the daily rate apart. A 7% nominal annual rate corresponds to a daily rate of 0.07 ÷ 365, or roughly 0.0192% per day. Entering 0.0192 into the rate field would describe a very different, much smaller yearly rate.
Daily Compound Interest Calculation Example
Suppose you start with 10,000 at a 7% nominal annual rate for 10 years. That gives 3,650 daily periods and a daily rate of about 0.00019178. The future value is approximately 20,136.18, so the interest earned is approximately 10,136.18 and the total growth is about 101.36%.
This example assumes no additional deposits, no withdrawals, a constant rate, and no taxes or fees. Any of those would change the outcome.
Daily Compounding vs. Monthly and Annual Compounding
When the nominal annual rate and the investment period are identical, more frequent compounding generally produces a higher ending balance. At 7% for 10 years on 10,000, annual compounding gives about 19,671.51, monthly compounding about 20,096.61 and daily compounding about 20,136.18. The difference between monthly and daily is modest, while the difference between annual and daily is larger.
These figures hold only under identical mathematical assumptions. Compounding frequency alone does not determine which real-world product is better, because fees, minimum balances, rate changes, taxes and other terms usually matter as much or more. If you want to compare other frequencies, the related calculators below cover annual and monthly compounding.
Nominal Interest Rate vs. Effective Annual Rate
The nominal rate is the stated yearly rate before compounding is applied. The effective annual rate (EAR) is the rate that describes actual growth over one year once compounding is included. For a 7% nominal rate compounded daily, the EAR is (1 + 0.07/365)^365 − 1, which is approximately 7.25%.
So 10,000 grows to about 10,725.01 after one year, not 10,700. The gap widens as the nominal rate rises. Looking at the EAR helps when comparing offers that quote the same nominal rate but compound at different frequencies.
Benefits and Limitations of Daily Compounding
This calculation is useful for building intuition, for sanity-checking a quoted figure and for seeing how time and rate work together. It also makes the effect of starting early visible, because the growth in later years is much larger than in early ones.
It is still only an estimate. It does not include:
- Fees and taxes, which reduce the amount you keep.
- Changing interest rates, since the model assumes a constant rate.
- Deposits or withdrawals made during the period.
- Different day-count conventions (for example 360 or 366 days) or product-specific crediting rules.
- Inflation, which reduces what the future amount can buy.
Daily compounding does not guarantee higher profit in every situation, and no result here is a promise of future returns.
Frequently asked questions.
What is a daily compound interest calculator?
A daily compound interest calculator estimates the future value of an amount when interest is calculated and added to the balance every day. You enter the principal, a nominal annual interest rate and a duration, and it returns the future value, interest earned and effective annual rate.
How do you calculate daily compound interest?
Divide the nominal annual rate by 365 to get the daily rate, multiply 365 by the number of years to get the number of periods, then grow the principal by (1 + daily rate) for each period. Subtract the original principal from the result to get the interest earned.
What is the daily compound interest formula?
A = P × (1 + r/365)^(365×t), where A is the future value, P is the initial principal, r is the nominal annual rate as a decimal and t is the time in years.
How much will 10,000 grow at 7% interest over 10 years with daily compounding?
Approximately 20,136.18 under the 365-day daily-compounding model, which is about 10,136.18 of interest. This assumes no additional deposits, no withdrawals, no taxes and no fees. Actual products may use different terms or methods, and investment returns are not guaranteed.
What is the difference between daily and annual compounding?
With annual compounding, interest is added once a year. With daily compounding, it is added every day, so interest starts earning interest sooner. At the same nominal rate and duration, daily compounding gives a slightly higher balance.
Is daily compounding better than monthly compounding?
Under identical positive rates and otherwise identical assumptions, daily compounding gives a slightly higher ending balance than monthly compounding. The difference is usually small, and real products differ in fees, taxes and terms, so compounding frequency alone does not decide which is better.
What is the effective annual rate for daily compounding?
It is (1 + r/365)^365 − 1. For a 7% nominal annual rate, the effective annual rate is approximately 7.25%. This daily compounding calculator shows it for any rate you enter.
Does this calculator use 365 or 366 days?
It uses a fixed 365-day year for every calculation, including leap years. A product that uses 360 or 366 days, or actual days elapsed, may give a slightly different result.
Does daily compounding include taxes, fees, deposits, or withdrawals?
No. The calculator models only the initial principal growing at a constant nominal rate. It does not include taxes, fees, extra deposits or withdrawals.
Is the calculated interest guaranteed?
No. The result is a mathematical estimate based on the values you enter. Actual interest and investment returns can differ and are not guaranteed.
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This calculator provides estimates based on the entered principal, nominal annual interest rate, duration, and a 365-day daily-compounding model. Actual financial products may use different day-count conventions, crediting rules, fees, taxes, or rate conditions. Results are for educational purposes only and do not guarantee future returns or constitute financial advice.