26 tools
Math
Evergreen maths tools for students and professionals
- Percentage Calculator
- Percentage Increase Calculator
- Percentage Decrease Calculator
- Percentage Difference Calculator
- Fraction Calculator
Free online calculators for every question
Find the answer, see the formula, and check the working. Private and instant.
Try it now: percentage calculator
Browse by category
15 tools
Date & Time
Dates, durations and time zones without the mental arithmetic
See all date & time tools36 tools
Health
Body, nutrition, fitness and pregnancy calculators
See all health tools25 tools
Finance
Loans, interest, savings and everyday money maths
See all finance tools43 tools
Unit Converters
Fast, exact conversions between common units
See all unit converters tools8 tools
Other Converters
Developer and everyday converters that run in your browser
See all other converters tools14 tools
Everyday & Education
Practical calculators for school, home and daily life
See all everyday & education toolsBuilt to be checked, not just trusted
Every page explains how the number is produced, so you can verify it or reuse the method in a spreadsheet.
Private by design
Numbers and files stay in your browser. Nothing you type is stored on our servers.
Formula and working on every page
See the equation, a worked example and the assumptions behind each result.
Tested against bad input
Empty fields, zero, negatives and huge values return a clear message instead of a wrong answer.
Frequently asked questions
Are these calculators really free?
Yes. Every calculator is free to use with no sign-up. The site is supported by ads, which you can decline in the cookie settings.
Is the information I enter stored or sent anywhere?
No. Calculations run in your browser and the numbers you type are not sent to our servers. We only record anonymous counts, such as whether a tool ran successfully, so we can fix tools that fail.
How accurate are the results?
Each calculator uses a published, standard formula that is shown on the page with a worked example. Health, pregnancy, tax and finance tools give estimates and are not professional advice.
Why do some calculators share the same page layout?
Similar tools, such as the length, weight and temperature converters, use one engine with different defaults. This keeps results consistent and lets you switch units without leaving the page.