Future value with monthly contributions

Also called: compound interest, compounding, projection

What today's pot plus regular monthly payments could grow to, with returns compounding along the way.

Formula

Future value = Pot × (1 + r)^years + Monthly × ((1 + rₘ)^months − 1) ÷ rₘ

Worked example

1. Monthly rate rₘ = (1 + 6.0%)^(1/12) − 1 = 0.487%
2. Today's pot grows to £5,000 × 1.060^20 = £16,036
3. Monthly payments grow to £300 × ((1 + 0.00487)^240 − 1) ÷ 0.00487 = £136,032
4. Together = £152,067 in future pounds

Result: £152,067

How to read it

Compounding means growth earns growth: the longer the time horizon, the more the final value comes from returns rather than what you paid in. If you raise contributions each year, the planner includes those increases too, so it'll be higher than this simple version.

See it with real numbers: Planner → (free account)