About AIPreciseTools

Free calculators that show their work.

AIPreciseTools is a collection of free, single-purpose calculators and utilities for everyday questions: what a loan will really cost, how much to tip, how old someone is to the day, what time a meeting lands in another time zone, and more.

How the tools work

The calculations run in your web browser, on your own device. A few features need the internet and say so where you use them: looking up a vehicle's official EPA mileage, community tip averages, and the optional AI tip advisor. There is no account or sign-up.

Each tool page explains the formula or method it uses, so you can check the result yourself. Where we rely on a published standard, such as the CDC's adult BMI categories, the Mifflin-St Jeor equation for calorie needs or the EFF wordlist for passphrases, we say so on the page.

How we build and check each calculator

  1. One page per question. People search for a specific answer, like "sales tax on $80" or "how much concrete for a 10 × 10 slab", not for a formula. Each calculator answers one question well, and links to the related ones.
  2. Published formulas. Each page shows the formula it uses and, where it relies on a standard or published figure, lists the source at the bottom of the page.
  3. Worked examples, tested. Every calculator is checked against the worked examples on its page, entering those numbers and confirming the answer to the cent. Newer calculators also run those checks automatically in a browser before every change goes live.
  4. Dated. Each page shows when it was last updated, because rates, limits and platform rules change.
  5. Your feedback. The "Report a problem" button on every calculator comes straight to us, and fixes are usually live within days.

Use our calculators on your site

Every calculator has an Embed button that gives you a code snippet for your website, blog or class page. It's free, resizes itself to fit, and works on phones. There's also a Cite button with APA, MLA, Chicago, Harvard and BibTeX formats for papers and homework.

Accuracy and limits

We test each calculator against worked examples, but the results are estimates meant to help you plan. They aren't financial, medical, legal or tax advice. For big decisions, such as taking out a mortgage or changing your diet, check the numbers with a qualified professional, your lender or your doctor.

Contact

Found a result that looks wrong, or want a new tool added? Use the contact page or email hello@aiprecisetools.com.