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Simple interest calculator
Simple interest never compounds: the same interest amount is charged every period on the original principal only.
{"type":"simple","outLabel":"Total interest","html":"\u003cdiv>\u003clabel class=\"f\" for=\"f-P\">Principal\u003c/label>\u003cspan class=\"meta\">$\u003c/span> \u003cinput id=\"f-P\" type=\"number\" value=\"10000\" min=\"0\" step=\"100\" inputmode=\"decimal\" style=\"width:100%\">\u003c/div>\u003cdiv>\u003clabel class=\"f\" for=\"f-rate\">Annual rate\u003c/label>\u003cspan class=\"meta\">%\u003c/span> \u003cinput id=\"f-rate\" type=\"number\" value=\"5\" min=\"0\" step=\"0.1\" inputmode=\"decimal\" style=\"width:100%\">\u003c/div>\u003cdiv>\u003clabel class=\"f\" for=\"f-yrs\">Years\u003c/label>\u003cinput id=\"f-yrs\" type=\"number\" value=\"3\" min=\"0\" step=\"0.5\" inputmode=\"decimal\" style=\"width:100%\">\u003c/div>","stats":"\u003cdiv class=\"stat\">\u003cspan>Total repaid\u003c/span>\u003cb id=\"s-tp\">—\u003c/b>\u003c/div>"}
How the math works
I = P × r × t
The rate r is the annual rate as a decimal and t the time in years. Total repaid is principal plus interest.
Frequently asked questions
Where is simple interest used?
Short-term personal loans, some auto loans and bonds use simple interest. Most mortgages and savings accounts use compound math instead.
Simple vs compound — which costs less?
For a borrower, simple interest costs less than compounding at the same rate, because interest never grows on top of interest.
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