Free, private and made for US users
Free online calculators that give you a clear answer, fast
Work out your mortgage payoff, take-home pay, taxes, BMI and more. Every calculator is free, works on your phone and never asks you to sign up.
- 100% free to use
- No sign-up needed
- Your numbers stay on your device
- Updated for 2026 rules
Free calculators
Pick a tool, type your numbers and read the answer.
How it works
Three steps, and nothing to install.
- 1
Pick a calculator
Choose a tool for your question, such as paying off a mortgage or working out take-home pay.
- 2
Enter your numbers
The answer updates as you type. There is no submit button and nothing to install.
- 3
Understand the result
Each page explains the formula in plain English, so you can check the answer yourself.
Why people use Tidy Math
A small, independent site that shows its working.
Numbers you can check
Every calculator explains its formula in plain English, so you can follow the maths yourself.
Private by design
The maths runs in your browser. The numbers you type never leave your device.
Based on official sources
Tax and health tools follow figures from the IRS and the CDC. Read our editorial policy.
Latest guides
Plain-English articles that explain the numbers.
Common questions
Are the calculators really free?
Yes. Every calculator on Tidy Math is free to use. There is no sign-up, no paywall and no limit on how many times you use them.
Do you store the numbers I type?
No. The maths runs in your browser, so the numbers you enter stay on your device. They are not sent to a server.
How accurate are the results?
Tax and payroll tools use the 2026 figures published by the IRS, and health tools use public formulas such as the CDC BMI categories. Results are estimates for planning and learning, so check them with a professional before a big decision.
Can I use Tidy Math on my phone?
Yes. Every page works on phones, tablets and desktops, and the answer updates as you type.
How often do you add new calculators?
New free calculators and guides are added regularly. Join the newsletter and you get one short email when something new launches.
Built by Muhammad Ahmad
Muhammad Ahmad is a full stack web developer from Lahore, Pakistan. He builds and maintains the calculators on this site and checks every formula against official sources such as the IRS and the CDC.
About the authorGet a note when a new calculator launches
One short email when we add a new free tool or guide. No spam, and you can unsubscribe at any time.