Free · Instant calculations
Simple and Compound Interest Calculator
Project savings with regular contributions and chosen compounding frequency.
How to use this tool
Choose the calculation method, enter your values and select Calculate. Reset clears results and restores the example inputs.
Formula
Compound growth = (1 + annual rate / c)^(c × years). Simple growth = 1 + annual rate × years. Apply growth to the initial balance and the remaining duration of each contribution.
Example
£1,000 at 10% compounded yearly for two years grows to £1,210, without contributions.
Assumptions and limits
Contributions occur at period end, with only completed contribution periods included. Fractional compounding periods use exponential growth. Fixed nominal annual rate; no tax, fees, inflation or withdrawals. Simple interest applies independently to each contribution.
Frequently asked question
When are contributions added? At the end of each selected period, not at its beginning.