Questions about the calculator
Short answers to the assumptions behind the numbers. The calculator itself is on the home page.
How is the investment return calculated?
The annual rate is nominal. It is divided by the number of compounding periods you choose, then applied to the balance at the end of each period. The starting amount earns a return in the first period. Money you add does not earn a return until the period after it arrives.
When are monthly contributions added?
At the end of each compounding period. Monthly compounding adds the contribution every month, after that month's growth. Quarterly compounding holds three monthly amounts and adds them as one sum at the quarter's end. Annual compounding holds a full year of contributions and adds them after that year's growth.
Does this include fees, taxes, or pay rises?
No. The contribution stays flat, and nothing is deducted for fund fees, platform charges, or tax. If you want a rough net return, lower the annual percentage by a fee estimate before you read the result. That is still an illustration, not a tax calculation.
What annual return should I type in?
Type a rate you want to test. A long stock-market average is a common starting point, and it is also a poor description of any single decade. Run the same contributions at a lower rate and treat the range as the useful output.
How does the inflation figure work?
Future value is in future money: the balance as it would be printed in that later year. Buying power divides each year's balance by compounded inflation, so a 2% inflation assumption shrinks the later years. Your monthly contribution is not increased with inflation. If you expect to raise contributions over time, this page will understate those later deposits.
Why doesn't the total match my brokerage?
A brokerage applies the return you actually received, on the days cash was invested, after fees and any tax withheld. This calculator applies one rate on a fixed timetable. Use it to understand the shape of a plan, then rely on your provider's statement for the account you hold.
Can I model a losing stretch?
Yes. Enter a negative annual return. The growth column will go negative and the balance can finish below the cash you contributed. Extremely negative rates that would pass through −100% inside one compounding period are blocked.
Is this financial advice?
No. Nothing here considers your age, debts, job security, tax residency, or how you would feel in a falling market. It does not recommend a fund, a platform, or an amount to invest. If you need advice, speak to someone authorised to give it where you live.
Do you keep the numbers I enter?
No. The schedule is calculated in your browser and disappears when you leave, apart from the CSV if you choose to download one. The currency menu is the only preference written to local storage on this device.
Does changing currency convert my savings?
No. Pounds, euros, dollars, and the other options are labels. 10,000 stays 10,000. Only the symbol and the way digits are grouped will change to match your browser's locale.