Exact date calculation
Calculate Simple Interest Between Two Dates
This calculator is for situations where a fixed number such as “30 days” is not precise enough. Enter the principal, annual rate, start date, and end date. The calculator counts the dates using the rule you select and applies simple daily interest using the selected day-count basis.
How Many Interest Days Are Between Two Dates?
There is not always one universal answer. A calculation can include the start date, include the end date, include both dates, or exclude both. The governing note, payoff statement, judgment, statute, contract, or other rule determines which convention applies.
Should the Start Date Be Included?
Do not assume the first day should always be counted. Identify the required convention before comparing your result with a lender statement, payoff quote, judgment calculation, or other interest figure.
Actual/360 vs. Actual/365 Interest
The number of calendar days and the day-count basis are separate choices. Actual/360 divides the annual rate by 360. Actual/365 divides the annual rate by 365. Because 360 is the smaller denominator, Actual/360 produces a slightly larger daily rate for the same annual percentage.
For the underlying calculation, see the daily interest formula.
Loan Interest Between Two Dates
Exact-date calculations are useful when interest accrues daily between scheduled payment dates, during a payoff period, or on a private note. If a payment, advance, credit, or other transaction changes principal during the period, use the Irregular Payment Loan Calculator.
Judgment Interest Between Two Dates
This calculator can perform simple-interest arithmetic when you already know the principal, annual rate, applicable dates, and required day-count method. It does not determine the legally applicable rate, compounding method, or required dates; those depend on the governing law, court order, jurisdiction, and facts.
Promissory Note Interest Between Two Dates
Private loans and promissory notes often require interest to be calculated between specific transaction dates. If payments occur on irregular dates, use an exact transaction-history calculation rather than treating the entire period as one unchanged balance.