Compound growth calculator with fees
Compound a return over many periods, with or without regular deposits, and see how much a small cost per period takes from the end result.
Calculations run in your browser. Nothing you type is sent or stored. Results are estimates for information only, not investment advice.
How it works
Compounding means each period's return is earned on the previous total, not only on the starting amount. With a starting amount P, a return g per period, n periods and an amount C added at the end of every period, the final value is:
Final value = P × (1 + g)n + C × ((1 + g)n − 1) ÷ g
The calculator runs this twice: once with the gross return g, and once with g minus the cost per period. The difference between the two is the amount the costs take. Because costs reduce the rate that is compounded, their effect also compounds, which makes them much larger over many periods than the cost figure suggests.
Worked example
The page opens with 1,000 earning 1% a day for 365 days, which is 1.01365 = 37.78 times the start, or 37,783. If costs take 0.1% of the account each day, the rate that compounds is 0.9%, and the final value is 26,319 (26.32 times). A cost of one-tenth of the daily return removes 30% of the final result.
What a daily return and a daily cost add up to in a year
| Return per day | No costs | With costs | Removed by costs |
|---|---|---|---|
| 0.1% a day | 1.44× | 1.00× | 31% |
| 0.25% a day | 2.49× | 1.73× | 31% |
| 0.5% a day | 6.17× | 4.29× | 30% |
| 1% a day | 37.78× | 26.32× | 30% |
The first row is the clearest: a 0.1% daily return earns 1.44 times the start in a year, and a 0.1% daily cost cancels it exactly. The reasons that a steady 1% a day is not a realistic target, whatever the arithmetic says, are laid out in what 1% a day would really mean. To see what your own trades cost, use the trading fee calculator.
Questions
Is the return per period an average or a promise?
Neither. It is a rate you type in. Real returns vary from period to period, and a steady rate is almost never achieved. A series that averages 1% a day with big swings grows less than a steady 1% a day.
Why do costs reduce the result by more than their size?
Because they reduce the rate that compounds. Over 365 periods, a small cut in the rate becomes a large cut in the final multiple, as the table shows.
What period should I use?
Any. The formula works the same for days, weeks, months or years, as long as the return, the cost and the number of periods use the same unit.
Does this include taxes?
No. Taxes, and the timing of deposits within a period, are left out.