Simple vs Compound Interest Calculator

Add a slider showing the "Cost of Waiting" to create high-intent financial urgency copy.

Note on errors: the most common slip-up here is rounding the wrong number, or forgetting a recurring cost that quietly changes the real total. If that happens, double-check your input rather than the tool — the calculation itself runs the same way every time.

Your data stays private. Everything you type runs locally in your own browser tab. Nothing is uploaded, logged, or stored on a server — close the tab and it's gone.

This tool processes everything client-side, inside your browser window, using standard arithmetic running in plain JavaScript the instant you click Calculate. Valid HTML structure for embedded mathematical formulas Nothing is sent to a server, so there's no upload delay and no privacy trade-off.