How the calculation works
Each month the balance grows with the return, a small part of the yearly cost is taken off, and your deposit is added.
Balance after the month = balance × (1 + return)1/12 × (1 − costs)1/12 + deposit
Over a year this equals multiplying the balance by (1 + return) × (1 − costs).Worked example
10,000 for 10 years, no deposits, 7% return before costs.
- Without costs: 10,000 × 1.0710 = 19,671.51.
- With costs of 1.5% a year: 10,000 × (1.07 × 0.985)10 = 16,912.20.
- The costs take 2,759.31, which is 14.0% of the value without costs.
What this calculator does not include
- Taxes and one-off trading or entry costs.
- A return that changes from year to year.
- Inflation.
Amounts are rounded for display only; the calculation itself is not rounded. Results are estimates for information, not financial advice. Last updated: 13 November 2026.
Frequently asked questions
Why do small costs matter so much?
Costs are taken from your balance every year, so they also take away the growth that money would have earned later. A cost of 1.5% a year may sound small, but over 20 years it can take a large share of the final value.
What should I fill in as costs?
Add the yearly percentage of the fund (often called the ongoing charges or TER), any platform or advice fee and other regular costs. Enter the total as one percentage. One-off trading costs are not included.
What is the lower cost scenario for?
To compare. Fill in the costs of an alternative, such as a cheap index fund, and you see how much more you keep.
Is the return before or after costs?
Before costs. Enter the return you expect from the investments themselves, and the calculator subtracts the costs from it.
Does this include tax or inflation?
No. Taxes and inflation come on top. For the effect of prices use the inflation calculator.