Free calculators
Quick, accurate answers for everyday numbers, updated as you type.
Percentage Calculator
Three calculators in one: percentage of a number, percentage of a total, and percentage change.
Age Calculator
Exact age in years, months and days, plus total days lived and your next birthday countdown.
Date Difference Calculator
Exact number of days, weeks, and years/months/days between any two dates.
VAT Calculator
Add VAT to a price, or find the price before VAT from the total.
Unit Converter
Metric and imperial, for length, weight, temperature, volume, area, speed and data.
Popular shortcuts
Each calculator does one kind of question properly, including the parts people usually get wrong: removing VAT (divide, don’t subtract), counting ages in calendar months, converting between gigabytes and gibibytes, or converting a meeting time across a daylight-saving change.
Nothing is sent anywhere — the numbers you type about your salary, your loan or your weight stay in the page.
Frequently asked questions
How accurate are the results?
The formulas are exact; results are displayed rounded to a sensible number of decimals. For money matters with legal weight, rely on your bank’s or accountant’s figures.
Do the calculators work offline?
Once a page has loaded, yes: all the maths happens in your browser.
Is anything I type saved?
No. Close the page and it’s gone.