How to use this daily compound interest calculator
- Starting amount. Your balance on the first day.
- Interest rate. Choose Per day for a daily return, such as 0.5% a day from a trading or staking plan. Choose Per year (APR) for a bank or loan rate; it is divided by 365 or 360 to get the daily rate.
- Time period. Enter a number of days, weeks, months or years. A month counts as 365 ÷ 12 days, rounded to whole days.
- Reinvest rate. 100% keeps every day's interest invested. A lower figure pays the rest out to you.
- Interest is added. Every day, 6 days a week or weekdays only (trading days).
The results show the final balance, the total interest, what you earn per day by the end and how quickly the balance doubles. The schedule groups days into weeks, months or years for longer periods, and the CSV download contains every row, including any hidden in the table preview.
Daily compound interest formula
With a daily rate r (as a decimal) and d days on which interest is added:
A = P × (1 + r)d
For a yearly rate, the daily rate is r = APR ÷ 365 (or ÷ 360 for some banks and loans). Example: $1,000 at 1% a day for 30 days is 1,000 × 1.0130 = $1,347.85.
In Excel or Google Sheets: =1000*(1+1%)^30 for a daily rate, or =10000*(1+4.5%/365)^365 for one year at a 4.5% APR, which returns $10,460.25.
Daily compounding table
What $1,000 becomes at different daily rates when every day's interest is reinvested and interest is added 7 days a week:
| Daily rate | 30 days | 90 days | 180 days | 365 days |
|---|---|---|---|---|
| 0.1% a day | $1,030 | $1,094 | $1,197 | $1,440 |
| 0.5% a day | $1,161 | $1,567 | $2,454 | $6,175 |
| 1% a day | $1,348 | $2,449 | $5,996 | $37,783 |
| 2% a day | $1,811 | $5,943 | $35,321 | $1,377,408 |
Small daily rates add up to very large numbers over a year, because each day's growth builds on the last.
Are daily returns realistic?
Daily compounding is powerful on paper. A steady 1% a day turns $1,000 into $37,783 in a year, a gain of about 3,678%. For comparison, broad stock market indexes have historically averaged roughly 7% to 10% a year over long periods, with losing years along the way.
Real trading returns vary from day to day and include losing days, fees and taxes. Schemes that promise a fixed daily profit are a classic warning sign of fraud. Use this calculator to understand the math or to check a bank rate, not as a forecast of trading profits.
Daily compounding in savings accounts
Many savings accounts calculate interest every day and credit it monthly. $10,000 at a 4.5% APR compounded daily for a year (365-day basis) grows to $10,460.25, an annual percentage yield (APY) of 4.602%. Monthly compounding at the same rate gives 4.594%, so the difference is small.
Some lenders and money-market products divide the yearly rate by 360 instead of 365. On a 360-day basis the same $10,000 reaches $10,466.79, $6.54 more. For monthly deposits into savings, use our compound interest calculator.
Reinvest rate and weekdays explained
Here is $1,000 at 0.5% a day for 90 days with different reinvest rates:
- Reinvest 100%$1,566.55
- Reinvest 50%, $251.97 paid out$1,251.97
- Reinvest 0%, $450.00 paid out$1,000.00
Reinvesting everything gives the largest final balance. Taking some interest as income lowers the balance but pays you along the way; at 0% you simply collect the same interest every day.
If interest is only added on weekdays, a year has 261 compounding days instead of 365. At 1% per trading day, $1,000 ends the year at $13,424 instead of $37,783.
How we calculate
The calculator steps through every calendar day. On each day that interest is added (the first 5, 6 or 7 days of every week), it calculates the day's interest on the current balance, adds the reinvested share to the balance and records the rest as paid out. The daily rate is your daily percentage, or your yearly rate divided by 365 or 360.
The doubling time is ln(2) ÷ ln(1 + daily rate × reinvest rate), converted from compounding days to calendar days. The equivalent yearly growth is (1 + daily rate)compounding days in a year − 1. Results are tested against the formula above, against independent textbook values and against edge cases such as 0% reinvest, weekday-only compounding and the 100-year limit.
Questions and answers
What is daily compound interest?
Daily compound interest means interest is calculated and added to the balance every day, so each day's interest also earns interest from the next day on. Many savings accounts calculate interest daily, and traders use the same idea to project a fixed daily percentage return.
How do I calculate daily compound interest?
Multiply the starting amount by (1 + daily rate) raised to the number of days. $1,000 at 1% a day for 30 days is 1,000 × 1.01^30 = $1,347.85. With a yearly rate, divide it by 365 (or 360) first to get the daily rate.
What does 1% daily compound interest turn into over a year?
$1,000 compounding at 1% every day for 365 days becomes $37,783, about 37.8× the starting amount. That is the math only: real investments almost never deliver a steady 1% a day, and offers that promise it should be treated as a red flag.
What is the reinvest rate?
The share of each day's interest that stays invested. At 100% everything compounds. At 50% half is kept invested and half is paid out to you, so the balance grows more slowly but you receive income along the way. At 0% nothing compounds and you earn simple interest.
Should I count weekends?
Bank interest usually accrues every calendar day, including weekends, so keep 7 days a week. Stock and forex markets trade on weekdays only, so choose 5 days a week to compound only on trading days. Some crypto platforms pay every day.
Is daily compounding much better than monthly?
Only slightly. At 4.5% a year, daily compounding gives an annual yield of 4.602% against 4.594% for monthly compounding. The rate itself matters far more than how often it compounds.
Methodology last reviewed . Spotted a problem? Tell us.