# How much daily interest will I get?

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.

- Page: https://www.acalculator.org/finance/daily-interest-calculator
- JSON spec: https://www.acalculator.org/finance/daily-interest-calculator.json
- Version: c86743a80616

## Default answer

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.

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| p | Balance | The amount the interest is worked out on: a savings balance or a loan balance. |
| r | Annual interest rate | The yearly interest rate, before dividing by the days in a year. |
| days | Number of days | How many days the balance earns or owes interest. |
| m | Interest | Simple interest on the balance only, or interest added to the balance every day (compounded daily). |
| basis | Days in a year | The days the annual rate is divided by: 365 for most savings accounts, 360 for many loans. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| interest | Total interest | The interest over all the days. |
| daily | Interest for one day | The first day’s interest: balance × annual rate ÷ days in a year. |
| balance | Balance after the days | The starting balance plus the total interest. |
| dailyRate | Daily rate | The annual rate ÷ the days in a year. |
| apy | Annual percentage yield | The yearly yield this interest gives, by the Regulation DD formula: 100 × ((1 + interest ÷ balance)^(365 ÷ days) − 1). |

## 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).

## Assumptions

- 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.

## Worked examples

1. p = $10,000.00, r = 5%, days = 30, m = simple, basis = 365 gives daily = $1.37, interest = $41.10, balance = $10,041.10, apy = 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. p = $1,000.00, r = 6%, days = 365, m = daily, basis = 365 gives interest = $61.83, apy = 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. p = $50,000.00, r = 7.25%, days = 90, m = simple, basis = 360 gives interest = $906.25, daily = $10.07, dailyRate = 0.020139%. Source: CFPB Regulation DD, 12 CFR 1030.7 (daily rate).
4. p = $2,500.00, r = 18%, days = 31, m = daily, basis = 365 gives interest = $38.50. Source: CFPB Regulation DD, 12 CFR 1030.7 (daily rate of 1/365 of the rate).

## FAQ

### 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.

## Sources

- Consumer Financial Protection Bureau, Regulation DD (Truth in Savings), 12 CFR 1030.7, Payment of interest: interest by a daily rate of at least 1/365 of the interest rate, or 1/366 in a leap year, retrieved 2026-10-01. https://www.consumerfinance.gov/rules-policy/regulations/1030/7/
- Consumer Financial Protection Bureau, Regulation DD, 12 CFR 1030 Appendix A, Annual Percentage Yield Calculation: APY = 100 [(1 + Interest/Principal)^(365/Days in term) − 1], retrieved 2026-10-01. https://www.consumerfinance.gov/rules-policy/regulations/1030/a/