About us
Why this site exists
This site grew out of a practical annoyance: trying to work out what a sum of money becomes when it compounds for twenty years, and finding that most calculators online were either incomplete, vague about their inputs, or wanted a phone number before showing a result. A compound interest calculator should be simpler than that — open it, type a few numbers, see the answer and the working.
So we built our own, and put the notes we collected along the way on the same site, in the hope that the next person does not have to read fifteen pages to understand what FV = PV × (1+r/n)nt actually says.
How the tools were built
All three calculators (compound interest, regular investing, present and future value) were developed by us from the standard textbook compound and annuity formulas, and they run entirely in your browser. While building them we checked the output against multiple textbooks and against hand calculations at several compounding frequencies, so that every formula and every row of the breakdown holds up to review.
To make the results visible we draw a growth chart and a yearly breakdown for every calculation. Understanding compounding is easier when you can see the curve steepen than when you memorise a formula.
Where we stand
- Math and education only — we sell nothing. We do not sell, broker or recommend any financial product, and there are no product links on this site.
- No investment advice. Every rate shown in the articles and tools is a hypothetical illustration. Decisions are yours to make.
- We respect your data. Everything you type into a calculator is computed in your browser. Nothing is uploaded or stored.
- Advertising keeps the lights on. Hosting and domain costs are covered by third-party advertising. We keep ad placements out of the way of the tools.
What we can and cannot do
What we can do: make these mathematical tools accurate and easy to use, and write clear educational content without padding.
What we cannot do: tell you what to buy, predict where markets go, or promise any rate of return. We do not do these things and do not intend to.
Contact
Found a calculation error, a layout problem, or disagree with something we wrote? Please tell us via the contact page. We read every message.