4 tools
Saving & Investing
Compounding is the one piece of financial arithmetic worth internalising. These tools project growth honestly in nominal and inflation-adjusted terms, and show how much of the outcome comes from contributions rather than returns.
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Compound Interest Calculator
Project what regular investing could grow to over decades and see the same figure in today's money, which is the number that tells you what it would actually buy.
This grows a starting balance and a stream of regular contributions at a rate you choose, stepping through the schedule period by period rather than applying a single closed-form annuity formula. It reports the nominal future value, what you put in, what the growth added, and the figure this page is built around: the same balance restated in today's purchasing power. A year-by-year timeline shows how the balance divides between contributions and growth over time, which is where the shape of compounding becomes visible: for the first decade or so the money you add dominates, and only later does the growth outrun it.
Open the compound interest calculatorAlso in saving & investing
Each one answers a different question, not a rephrasing of the same one.
- Savings Goal Calculator Work out what you would have to put aside each period to reach a specific amount by a specific date, and what the rate you assume is really doing to that figure.
- Investment Return Calculator Work out what an investment actually returned, both in total and per year, and see why the total on its own cannot be compared with anything.
- Inflation Calculator See what a sum would need to grow to just to stand still, and what it will actually buy if it does not. Two figures, both true, running in opposite directions.
Answered here
Questions these tools actually answer.
Each links to the tool that answers it, where the full explanation sits beside the calculation.
- Why is the inflation-adjusted figure so much lower than the projection? Compound Interest Calculator
- Does compounding frequency make much difference? Compound Interest Calculator
- What return rate should I use? Compound Interest Calculator
- Does it matter whether I contribute at the start or the end of the month? Compound Interest Calculator
- Why does the calculator show an effective rate lower than the rate I entered? Compound Interest Calculator
- How much do fees and taxes take out of this? Compound Interest Calculator