Runway Labs builds small, single-purpose tools that answer one question properly instead of many questions vaguely. The first is the runway calculator: how long does a pot of money last if you withdraw a fixed amount every month?
Most financial calculators online have the same problems. They bury a simple answer under sign-up walls, they show a single number with no working, or they exist mainly to route you towards a product. If you want to know when your savings run out, you should be able to type three numbers and see the answer along with every month of the arithmetic behind it.
That is the whole design brief. No account, no email capture, no lead generation, no recommendations about what you should buy.
The method is stated openly on the calculator page rather than hidden. Each month the balance earns one-twelfth of the annual return you enter, then your withdrawal is subtracted, and the result carries forward. The tool repeats that until the balance reaches zero and reports the number of months.
The full month-by-month and year-by-year tables are shown so you can check the arithmetic yourself. Every assumption and known limitation is documented on the calculator page — including that inflation, tax, and variable returns are deliberately not modelled.
Runway Labs is an independent project built and maintained by a single developer in India. It is not affiliated with any bank, broker, mutual fund, or financial services company, and it does not receive commission from anyone.
I am a software developer, not a financial adviser. What I can vouch for is the arithmetic: the formula is published, the intermediate steps are visible, and the tool has been tested against edge cases. What I cannot do is tell you what to do with your money — that requires someone licensed who knows your circumstances.
The tools are free and always will be. Running costs are covered by advertising, which is clearly labelled and kept separate from the tools and navigation. Advertisers have no input into the calculations or the content, and there are no affiliate links or paid placements.
If you find a number that looks wrong, please tell me. Arithmetic errors on a page about money matter, and I would rather fix one than defend it.