Project a lump sum forward at a given rate, with optional recurring contributions and a choice of compounding frequency. It reports what you put in against what the interest added, which is the comparison that makes compounding legible. Nothing here accounts for tax, fees or inflation.
Runs entirely in your browser
Compound interest is the effect of earning interest on your interest, and over time it is what makes saving and investing grow. This calculator projects a starting sum forward at a given rate, with optional regular contributions and a choice of how often interest compounds, and shows the future value at the end of the period.
Crucially, it separates what you put in from what the interest added. Seeing your total contributions next to the interest earned is what makes compounding legible — early on the contributions dominate, but given enough time the interest can overtake them, which is the whole argument for starting early. Adjusting the rate, the contribution and the term shows how each lever moves the result.
One honest limitation: the projection does not account for tax, fees or inflation, so the real spending power of the final figure will be lower. Treat it as an illustration of how compounding works and a way to compare scenarios, not a guaranteed outcome. It runs in your browser, so your figures stay private.
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