How the categories are organized
We group tools by the job they do, not by the technology behind them. A mortgage calculator and a savings goal tool both sit under money, even though the math differs. A title tag tester and a robots.txt checker both sit under SEO.
If you're not sure where something lives, try the all-tools page, which lists everything in one place. Your browser's find command works well there.
For money and business
Finance and personal finance cover loans, mortgages, interest, retirement, inflation and take-home pay for several countries. SaaS tools model MRR, churn, LTV, CAC payback and runway. E-commerce tools work out profit after fees on Amazon, Etsy, Shopify and print on demand.
Freelance, HR and legal tools cover hourly rates, quotes, salary negotiation, cost per hire and statute-of-limitations lookups. Marketing tools check ad break-even and A/B test significance.
For websites and developers
SEO tools preview search snippets, test titles by pixel width, build canonical and hreflang tags, check robots.txt and generate schema. Web dev tools build CSS for layout, shadows, gradients, clip paths and motion. Dev tools format JSON, test regular expressions and explain status codes.
Most of them are made for the person who has a quick question mid-task and doesn't want to read a manual first.
For everyday life
Health tools estimate calories, macros and body measures. Pet tools convert dog, cat, bird and reptile ages. Hobby tools cover photography depth of field, aquariums and similar. Math and unit tools convert length, weight, volume and temperature, and handle fractions and percentages.
Productivity tools include a Pomodoro timer, working-days counters and a meeting planner across time zones.
A few ground rules
Tools are free and need no account. They give estimates for general information. Don't treat a calculator as financial, medical or legal advice. Rates and rules change, and your case may differ.
Missing something? Use the contact page. If a request has a clear use case, it moves up the list.
Finding the right calculator fast
Start with the category that matches your goal. Money questions live under Finance, Real Estate, E-commerce and SaaS. Health, Pets and Hobbies cover the everyday. Developers and designers will want Web Dev, SEO and Privacy.
If you know the task but not the tool name, use the search box. Type what you're trying to work out, like loan, break even or macros, and the matching tools appear.
Each tool has a short guide on its page and, for many, a longer article in Learn with a worked example.
How the tools are built
The math runs in your browser. We keep calculators simple, show the formula where it helps and state our assumptions. When rates or rules change, we update the source and the page date.
We'd rather have fewer tools that are right than a long list that's sloppy. If something is wrong or missing, tell us through the contact page.
Finding the right tool fast
The list on this page is long on purpose. Use the category links to jump to a group, or the search box if you know a word from the tool's name. If you're not sure what to call what you need, describe it in two words, like 'loan payment' or 'image size', and see what comes up.
Every tool runs in your browser. Your numbers don't get sent to a server, and there's nothing to install or sign up for.
New tools arrive in batches. If something you use often is missing, tell us on the contact page. A clear use case moves a request up the list.
How to get more from the list
Open two tools side by side when a task has two parts. A loan figure from the mortgage calculator, for instance, feeds straight into a budget check. Bookmark the pages you use weekly so they're one click away.
If a result looks off, re-read the input labels. Percent versus decimal and monthly versus yearly are the usual culprits. Each page has a worked example you can compare against.
Tell us what's missing. Short, specific requests are the easiest to act on.