What is a Daily Interest Calculator?

A daily interest calculator is a financial tool that helps you determine how much interest you'll earn on your principal amount over a specific number of days. Unlike traditional interest calculations that often use monthly or annual periods, this calculator provides a precise day-by-day calculation, making it ideal for short-term investments or loans.

When to Use a Daily Interest Calculator

This calculator is particularly useful in several situations:

When calculating interest for short-term deposits or loans that don't follow standard monthly cycles

When you need to determine the exact interest earned up to a specific date

When comparing different investment options that use daily compounding interest rates

How to Calculate Daily Interest

Daily interest calculations involve the following formula:

Daily Interest = Principal × (Annual Rate ÷ 365) × Number of Days

Where:

Principal is the initial amount of money

Annual Rate is the yearly interest rate (in percentage)

Number of Days is the period for which you want to calculate interest

The calculation process follows these steps:

Convert the annual interest rate to a daily rate by dividing by 365

Multiply the principal by the daily rate

Multiply this amount by the number of days

Daily Rate = Annual Rate ÷ 365 ÷ 100

Daily Interest = Principal × Daily Rate × Days

Total Amount = Principal + Daily Interest

Examples of Daily Interest Calculation

Example 1: Short-term Deposit

You deposit $5,000 at an annual interest rate of 3% for 30 days. How much interest will you earn?

Parameter

Value

Principal

$5,000

Annual Interest Rate

3%

Days

30

Daily Rate

0.00822% (3% ÷ 365)

Daily Interest

$12.33

Total Amount

$5,012.33

Example 2: Loan Interest

You borrow $10,000 at an annual interest rate of 6% for 15 days. How much interest will you need to pay?

Parameter

Value

Principal

$10,000

Annual Interest Rate

6%

Days

15

Daily Rate

0.01644% (6% ÷ 365)

Daily Interest

$24.66

Total Amount

$10,024.66

Example 3: Comparing Investment Options

You're comparing two investment options: Option A offers 3.5% annual interest for 60 days on $7,500, while Option B offers 3.65% annual interest for 45 days on the same amount. Which option yields more interest?

Parameter

Option A

Option B

Principal

$7,500

$7,500

Annual Interest Rate

3.5%

3.65%

Days

60

45

Daily Rate

0.00959% (3.5% ÷ 365)

0.01% (3.65% ÷ 365)

Daily Interest

$43.15

$33.78

Total Amount

$7,543.15

$7,533.78

Option A yields more interest despite the lower rate because the investment duration is longer.

Related Calculators

For more comprehensive financial planning, you might also find these calculators useful:

Simple Interest Calculator

Compound Interest Calculator

Savings Interest Calculator

Loan Interest Calculator

APY Calculator