Compound return calculator
See how a starting amount and regular contributions could grow when returns compound year after year.
How compounding works
Compounding means your returns start earning returns of their own. Each period, growth is applied to a slightly bigger base — so the curve bends upward over time rather than rising in a straight line. Regular contributions accelerate it, because every dollar you add gets more years to compound.
monthly rate = (1+r)^(1/12) − 1 · each month: balance = (balance + contribution) × (1 + monthly rate)
The annual return you enter is the effective yearly rate — it’s converted to an equivalent monthly rate, so 8% grows a lump sum by exactly 8% over twelve months. The model assumes a constant return, each contribution added at the start of its month (before that month’s growth), and no taxes or fees. Real markets don’t return the same amount every year — treat the result as a rough illustration of the shape of compounding, not a prediction.
Illustrative projection, not a forecast or a guaranteed return. Educational tool, not financial advice. Your figures never leave the page — the calculation runs entirely in your browser. The page loads standard pageview analytics, which never sees your numbers.
This math stops at what you typed in.
Tradune runs it continuously on your real holdings — with your money-weighted return next to a buy-and-hold SPY twin, and SEC insider filings flagged on the stocks you own.
Educational analytics — not investment advice.