Simple interest

Calculate simple interest from principal, an annual rate and a period with explicit day-count assumptions.

Calculation result

Adjust the example inputs, then calculate to see your result.

Interest = principal × annual rate × year fraction. No compounding, tax or fees. Results round to two decimals, half up.

Enter principal and an annual simple-interest rate using percent per year as labeled.

Choose years, days or calendar dates. Days mode divides by 365; calendar-date mode offers actual/365 or actual/actual by year.

Read interest separately from principal plus interest. Simple interest does not add accrued interest back to the calculation base.

10,000 THB at 5% annual simple interest for one year earns 500 THB, for a total of 10,500 THB.

Keep principal and rate fixed and extend one year to two. Simple interest scales with time rather than compounding.

Where does my information go?

Calculations run in your browser. Financial inputs are neither saved locally nor sent to analytics. Reloading restores the initial values.

What are this model’s limitations?

Changing balances and credited interest are excluded. For monthly contributions, use a model that supports them.