DIY9lives is a set of free calculators for freelancers pricing a job, homeowners measuring a room, and anyone comparing a paycheck, a car, or a loan. Open a tool, read how the number is made, and leave. Nothing asks you to sign up.
Most of the math runs in your browser. The VIN decoder and the currency converter are the exceptions; they call a public database and a daily exchange-rate feed. That is spelled out on the privacy page.
Body size, calories, sleep, cycle dates, and training zones. These are screening estimates, not a diagnosis.
Tips, percentages, ages, units, dates, and a password check that stays on your device.
Take-home pay, loan payments, what house a salary supports, and a retirement balance in today’s dollars.
What to charge, what to set aside for 1099 tax, and a proposal or invoice you can print.
Price after tax, the loan, fuel, tire size, and what the car is likely to be worth later.
Paint, concrete, flooring, rent versus buy, and whether a solar array pays for itself.
Poker equity, the expected value of a bet, and a typing-speed test.
Scale a recipe, convert cups and grams, and see what one serving actually costs.
Word counts, a readability score, headline checks, and a word-by-word diff.
Stacked discounts, and price per ounce so the bigger box is not assumed to be cheaper.
Dog and cat age in human years, using a curve instead of multiplying by seven.
The same short form for a calculator that is wrong and for a tool that should exist. You can also email diy9lives@gmail.com.
Each tool page keeps its original how-it-works note and adds a worked example plus sources. All guides. Checked October 29, 2026.
If a number on a calculator looks wrong, say which tool and what you typed. That is how the formulas get corrected. Sharing the link is useful too, because the site stays free that way.