acalculator

How much daily interest will I get?

Type the balance, the annual rate and the number of days. The daily interest calculator divides the rate by the days in a year and shows the interest for one day, the total, and the APY.

Your numbers

Read to 6 decimal places.
Interest
Total interest
$41.10

$10,000.00 at 5% for 30 days earns $41.10 of interest, $1.37 a day.

Interest for one day
$1.37
Balance after the days
$10,041.10
Daily rate
0.013699%
Annual percentage yield
5.12%

Total interest: $41.10. $10,000.00 at 5% for 30 days earns $41.10 of interest, $1.37 a day.

The results are estimates for information only. They are not financial, tax, or legal advice. Check the numbers with your lender or a qualified professional before you decide. Terms of use

How to calculate

Computes the interest a balance earns or owes each day (annual rate ÷ 365, 360 or 366) and the total over a number of days, as simple interest or compounded daily, with the APY.

Example with the default inputs (Balance $10,000.00, Annual interest rate 5%, Number of days 30, Interest Simple, Days in a year 365 days): $10,000.00 at 5% for 30 days earns $41.10 of interest, $1.37 a day.

Method: Daily rate = annual rate ÷ days in a year. Simple: interest = balance × annual rate × days ÷ days in a year. Daily compounding: interest = balance × ((1 + annual rate ÷ days in a year)^days − 1). APY = 100 × ((1 + interest ÷ balance)^(365 ÷ days) − 1).

  • The balance does not change during the days, apart from interest added daily when compounding.
  • The rate is read to 6 decimal places of a percent; each money amount is worked out exactly, and its shown cents are the exact value rounded half up.
  • No fees, deposits, withdrawals or payments.

Machine-readable copies: Markdown, JSON.

Worked examples

Each example is checked against the calculator on every build.

  1. Balance $10,000.00, Annual interest rate 5%, Number of days 30, Interest Simple, Days in a year 365 days gives Interest for one day $1.37, Total interest $41.10, Balance after the days $10,041.10, Annual percentage yield 5.116339%.Source: CFPB Regulation DD, 12 CFR 1030.7: interest by a daily rate of at least 1/365 of the interest rate (https://www.consumerfinance.gov/rules-policy/regulations/1030/7/, retrieved 2026-10-01); APY formula from 12 CFR 1030 Appendix A (https://www.consumerfinance.gov/rules-policy/regulations/1030/a/)
  2. Balance $1,000.00, Annual interest rate 6%, Number of days 365, Interest Compounded daily, Days in a year 365 days gives Total interest $61.83, Annual percentage yield 6.183131%.Source: CFPB Regulation DD, 12 CFR 1030 Appendix A: APY = 100 [(1 + Interest/Principal)^(365/Days in term) − 1], and for a 365-day term APY = 100 (Interest/Principal) (https://www.consumerfinance.gov/rules-policy/regulations/1030/a/, retrieved 2026-10-01)
  3. Balance $50,000.00, Annual interest rate 7.25%, Number of days 90, Interest Simple, Days in a year 360 days (banker’s year) gives Total interest $906.25, Interest for one day $10.07, Daily rate 0.020139%.Source: CFPB Regulation DD, 12 CFR 1030.7 (daily rate)
  4. Balance $2,500.00, Annual interest rate 18%, Number of days 31, Interest Compounded daily, Days in a year 365 days gives Total interest $38.50.Source: CFPB Regulation DD, 12 CFR 1030.7 (daily rate of 1/365 of the rate)

How it works

With P the balance, r the annual rate as a decimal (5% is 0.05), Y the days in a year (365, 360 or 366) and n the number of days:

  • Daily rate = r ÷ Y.
  • Interest for one day = P × r ÷ Y. With daily compounding this is the first day's interest; later days earn a little more.
  • Simple interest: total interest = P × r × n ÷ Y.
  • Compounded daily: total interest = P × ((1 + r ÷ Y)^n − 1).
  • Balance after the days = P + total interest.
  • Annual percentage yield = 100 × ((1 + total interest ÷ P)^(365 ÷ n) − 1), the Regulation DD formula. For n = 365 it equals 100 × total interest ÷ P.

Exact arithmetic. The rate is read to 6 decimal places of a percent, and the balance as the decimal you typed. The interest, the balance and the daily interest are then worked out as exact ratios of whole numbers, and each shows the exact ratio rounded half up to the cent, so a value just below a half cent never shows the cent above (the stored number is the nearest float, moved by a few float steps when a float near a half cent would print other cents). The APY uses the exact ratio of interest to balance (cut to 20 decimal places). The daily rate shows to 6 decimal places and the APY to 2, both rounded half up; the APY power runs in floating point.

Rules

  • The balance is from $0.01 to $1,000,000,000,000.
  • The annual rate is from 0% to 100%.
  • The number of days is a whole number from 1 to 3,660 (about 10 years).
  • The balance stays the same apart from daily compounding: no deposits, withdrawals, payments or fees.

Worked examples by hand

$10,000 at 5%, 30 days, simple, 365-day year. Daily interest = 10,000 × 0.05 ÷ 365 = 1.369863, shown as $1.37. Total = 10,000 × 0.05 × 30 ÷ 365 = 41.09589, shown as $41.10. APY = 100 × ((1 + 41.09589 ÷ 10,000)^(365 ÷ 30) − 1) = 5.12%.

$1,000 at 6%, compounded daily for 365 days. Interest = 1,000 × ((1 + 0.06 ÷ 365)^365 − 1) = 61.8313, shown as $61.83. APY = 100 × 61.8313 ÷ 1,000 = 6.18%.

$50,000 at 7.25% for 90 days on a 360-day year. Interest = 50,000 × 0.0725 × 90 ÷ 360 = $906.25 exactly; daily interest = 50,000 × 0.0725 ÷ 360 = $10.07; daily rate = 7.25 ÷ 360 = 0.020139%.

$2,500 at 18% compounded daily for 31 days. Interest = 2,500 × ((1 + 0.18 ÷ 365)^31 − 1) = 38.5032, shown as $38.50.

Other questions people ask

How do I calculate daily interest?

Divide the annual rate by the days in a year, then multiply by the balance. $10,000 at 5% earns 10,000 × 0.05 ÷ 365 = $1.37 a day, or $41.10 over 30 days with simple interest.

Should I divide by 365 or 360?

Use what your bank or lender uses. US savings accounts must use a daily rate of at least 1/365 of the rate (1/366 is allowed in a leap year). Many business and commercial loans use a 360-day year, which makes each day’s interest a little higher.

What is the difference between simple and daily compounding?

Simple interest is worked out on the starting balance only. With daily compounding, each day’s interest is added to the balance, so the next day earns interest on it too. $1,000 at 6% for a year earns $60.00 simple, or $61.83 compounded daily.

What is APY?

The annual percentage yield: the interest a year would earn, as a percent, including compounding. The calculator uses the Regulation DD formula, 100 × ((1 + interest ÷ balance)^(365 ÷ days) − 1). 6% compounded daily is an APY of 6.18%.

How much interest does a credit card charge per day?

Card issuers use a daily periodic rate: the APR ÷ 365 (some use 360). An 18% APR on $2,500 is about $1.23 a day; compounded daily over a 31-day cycle it adds up to $38.50.

Why is my bank’s number slightly different?

Banks round the daily rate and each day’s interest in their own way, may credit interest monthly instead of daily, and the balance usually changes during the period. This calculator keeps the balance fixed and rounds only the final amounts.