CoolCalculators is a free collection of 190+ online calculators covering finance, fitness, health, food, gaming, nature, and a fair bit of fun along the way. Some are everyday tools you've probably needed before, like a tip or percentage calculator. Others are the kind of thing you didn't know you wanted until you saw it, like a cost-of-a-grudge calculator or a party snack planner.
We won't pretend every one is a stroke of genius. Some are simply solid and useful, and some are here because they were worth having in the collection. What they share is a build standard: fast, clear, and correct, with the same straightforward experience whether you're checking your BMI or estimating surf conditions.
CoolCalculators is made by Claudea Wild & the Wild Ones. The Wild Ones are two women with an endless supply of "wait, has anyone actually calculated that?" ideas. The ideas, the look and feel, and the decisions about what gets built are theirs, especially the niche and unusual calculators.
They build it in partnership with AI. Claudea Wild is Claude, the AI made by Anthropic. The name started with an AI agent we run on OpenClaw, and it has become the name we use for Claude's part in the work: helping research formulas, write the code, and test the math. The humans steer and the AI helps get it built and checked, and we're upfront about that.
Each calculator starts with a question. We look up the standard formula, or the closest thing to one, run test numbers through it, and explain the method in the guide below the calculator: how the result is calculated, what it means, and where it falls short.
Where a calculator relies on outside data, such as sunrise and sunset times, tides, moon phases, and wildlife sightings, it pulls from public sources like NOAA, Open-Meteo, and GBIF rather than guessing.
We're always adding new calculators and refining existing ones. We can still get things wrong, so if a result looks off, tell us and we'll take a look.
We're not doctors, dietitians, financial advisors, or lawyers, and we don't pretend to be. Our calculators give estimates for general information, not personal advice. For anything with real stakes, like your health, your money, or a legal decision, please check with a qualified professional.
CoolCalculators is free to use. We keep it that way through advertising and affiliate links, and we like to be upfront about it. Some product links on our pages are Amazon affiliate links, which means we may earn a small commission if you buy, at no extra cost to you, and the disclosure appears wherever those links do. We do our best to link practical, well-made things, and sustainable ones where we can. You can read more in our Privacy Policy.
If you spot something that looks off, want a calculator we don't have yet, or just want to say hi, we'd like to hear from you. Visit our Contact page to get in touch.