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Compound Daily Interest Calculator

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Your Results

Starting with $100.00 on Nov 9, 2026 and earning 1% a day, your balance grows to $116.10 by Nov 24, 2026. Over 15 days you earn $16.10 in total, which is $1.10 more than without compounding. A rate of 1% a day equals 3,678.34% a year if it continues and is fully reinvested, far above what savings accounts pay, so be careful with any offer promising daily returns like this.

$116.10
Ending balance after 15 days
$16.10
Total Earnings
$0.00
Cash Withdrawn
Nov 24, 2026
End Date
3,678.34%
Equal to per Year
Daily Schedule
DayDateEarningsWithdrawnBalance
0Nov 9$0.00$0.00$100.00
1Nov 10$1.00$0.00$101.00
2Nov 11$1.01$0.00$102.01
3Nov 12$1.02$0.00$103.03
4Nov 13$1.03$0.00$104.06
5Nov 14$1.04$0.00$105.10
6Nov 15$1.05$0.00$106.15
7Nov 16$1.06$0.00$107.21
8Nov 17$1.07$0.00$108.29
9Nov 18$1.08$0.00$109.37
10Nov 19$1.09$0.00$110.46
11Nov 20$1.10$0.00$111.57
12Nov 21$1.12$0.00$112.68
13Nov 22$1.13$0.00$113.81
14Nov 23$1.14$0.00$114.95
15Nov 24$1.15$0.00$116.10

What Is Compound Daily Interest?

Compound daily interest means interest is worked out every day on your balance, including the interest already added. Each day's earnings then earn interest of their own, so the balance grows a little faster each day than it would with simple interest, which is only ever paid on the original amount.

You don't have to reinvest everything. The reinvest rate sets how much of each day's earnings stays invested; the rest is withdrawn as cash. Only the part you reinvest compounds.

Daily rates vs yearly rates

  • Small daily rates are large yearly rates: 1% a day equals about 3,678% a year if it continues and is fully reinvested.
  • Savings accounts quote a yearly rate: a 4% yearly rate compounded daily pays about 0.011% a day, so enter that small number here to model one.
  • Be careful with daily-return promises: offers of 1% a day or similar are far above what regular savings or investments pay, and they are a common sign of fraud.

Which calculator should I use?

  • This calculator: for a daily rate, followed day by day, with the choice of reinvesting only part of the earnings.
  • Compound Interest calculator: for savings and investments with a yearly rate, over months or years, with regular deposits or withdrawals.

How to Calculate Compound Daily Interest

With all earnings reinvested, the balance after n days is:

FV=PV×(1+r)n
  • FV: the future value, or ending balance.
  • PV: the present value, or starting amount.
  • r: the daily interest rate.
  • n: the number of days that earn interest.

If you reinvest only part of the earnings, multiply the rate by the reinvest rate: r × reinvest rate. The rest of each day's earnings is withdrawn as cash.

Example

$100 at 1% a day for 15 days, with everything reinvested:

  • Day 1: $100 × 1% = $1.00 of earnings, so the balance is $101.00.
  • Day 2: $101.00 × 1% = $1.01 of earnings, so the balance is $102.01.
  • Day 15: $100 × 1.0115 = $116.10
  • Without compounding, you would earn $1 a day and end with $115.00.

How to Use the Compound Daily Interest Calculator

"If I put $100 somewhere that earns 1% a day and reinvest everything, how much will I have after 15 days?" This calculator answers that.

Let's enter the numbers for this example in each box. They are already filled in when the calculator opens, so you can follow along and then change any box to match your own numbers.

  • Starting Amount: Enter 100, which is the money you start with. It must be greater than 0.
  • Daily Interest Rate: Enter 1, which is the percent earned each day. It must be from 0 to 100.
  • Number of Days: Enter 15, which is how many days earn interest. It must be a whole number from 1 to 10,000.
  • Reinvest Rate: Enter 100, which is the percent of each day's earnings that stays invested. The rest is withdrawn as cash. It must be from 0 to 100.
  • Start Date: Leave it at today, which is the day the money goes in. The first earnings arrive the next counted day.
  • Include Weekends: Leave it at Yes, so every day earns interest. Choose No to skip Saturdays and Sundays, which moves the end date later but doesn't change the amounts.

Calculate and Reset

Click Calculate to see your results. If a box has a problem, such as a result too large to show, a message pops up under that box instead. With the default numbers you get:

  • Your Results: a short summary in words: the ending balance ($116.10), total earnings, what compounding added, and the yearly rate this daily rate equals.
  • Ending Balance: the headline number.
  • Total Earnings, Cash Withdrawn, End Date and Equal to per Year: $16.10, $0.00, the last counted day, and about 3,678%.
  • Growth chart: the starting amount, reinvested earnings and any cash withdrawn, stacked over time. The dashed line shows growth without compounding, so the gap is what compounding adds. A link under it opens the Compound Interest calculator with your numbers filled in, when the yearly rate is under 100%.
  • Daily Schedule: each day's date, earnings, total withdrawn and balance. More than a year of days is shown by month. Download Excel saves every day with the formulas, so you can change the amount or a rate at the top of the file and see the results update.
  • Share Results: a link that opens this calculator with your numbers filled in. Copy it, or share it on Facebook or X.

Amounts of $1 million or more are shortened, for example $1.25M. Click Reset to put every box back to its default and show the default results again.

Video: How to Use the Compound Daily Interest Calculator