Calculate interest that accrues only on the original principal using a transparent simple-interest formula.
I = P × r × tCalculate non-compounding simple interest and total amount across years, months or days with 365-day and 360-day conventions.
Simple interest calculates interest only on the original principal. Interest already accrued is not added back to the principal for future interest calculations.
Toolmera uses I = P × r × t, where P is principal, r is the annual rate as a decimal and t is time expressed in years.
Simple interest grows linearly because the interest base remains the original principal. Compound interest can grow faster because accumulated interest is added to the balance and can itself earn interest.
Use the Compound Interest Calculator when interest is periodically capitalized or when recurring contributions are part of the scenario.
For day-based periods, Toolmera lets you choose a 365-day year or a 360-day banking convention. The selected basis changes how a number of days is converted into a fraction of a year.
Real contracts can use their own day-count conventions, so check the applicable agreement when the exact contractual interest amount matters.
Open the tool and select the mode or options that match your task.
Provide the inputs required for the result.
Check the calculation, assumptions and supporting output shown by Toolmera.
Useful next steps in the same workflow.
Toolmera converts months to years by dividing the number of months by 12, then applies I = P × r × t.
Choose either a 365-day year or a 360-day banking basis; Toolmera divides the number of days by that basis.
No. Interest is calculated only on the original principal in this tool.
Compound interest can earn interest on prior interest; simple interest does not.