Daily Interest Calculator: How to Calculate Daily Interest
Learn how to calculate daily interest, daily interest on a loan, and average daily balance style interest with clear formulas and examples.
Searching daily interest calculator usually means you want to know how much interest builds up each day on a balance. This is common for loans, credit cards, savings, and overdue balances.
Daily Interest Formula
Daily interest = Balance x (Annual rate / 365)
If the annual rate is given as a percentage, convert it to a decimal first.
Example:
- Balance: $10,000
- Annual rate: 7%
Daily rate = 0.07 / 365 = 0.00019178
Daily interest = 10,000 x 0.00019178 = $1.92 per day
Daily Interest on a Loan
Many loans accrue interest daily based on the outstanding principal. As the principal falls, the daily interest charge usually falls too.
This is why making a payment earlier can reduce total interest slightly on some loan types.
Average Daily Balance Method
Credit cards often use an average daily balance method. Instead of charging interest on one fixed balance, the lender averages the daily balances in the billing cycle, then applies the periodic rate.
A simplified approach is:
- Add each dayโs balance.
- Divide by the number of days in the cycle.
- Apply the daily or periodic rate.
Common Mistakes
Forgetting to convert percent to decimal leads to huge errors.
Using 360 instead of 365 changes the result. Some contracts use 360-day conventions, so always check the loan terms.
Applying daily interest to the wrong balance can skew the estimate.
The Bottom Line
To calculate daily interest, divide the annual rate by 365 and multiply by the balance. For loans and credit cards, confirm whether the lender uses a different day-count rule or average daily balance method.
Use the Loan Calculator for broader payment and interest estimates.
How to Calculate: Step-by-Step Guide
Find the annual rate
Use the APR or yearly interest rate as a percentage.
Convert it to a daily rate
Divide the annual rate by 365 unless your contract uses a different day-count rule.
Multiply by the balance
Apply the daily rate to the current principal or average daily balance.