Unit converter
Unit converter handles the usual dimensions plus Celsius, Fahrenheit, and Kelvin.
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Calculators
Units, temperatures, dates, BMI, timezones, and percentage math — all in the browser.
Runs in your browser · Nothing uploaded
- Unit converterLength, weight, volume, area, speed, and temperature (including C, F, and K).Runs in your browser · Nothing uploaded
- Timezone converterCurrent time in two zones and the offset between them.Runs in your browser · Nothing uploaded
- Percentage calculatorX% of Y, X is what % of Y, and percentage change.Runs in your browser · Nothing uploaded
- Date differenceYears, months, days, and total days between two dates.Runs in your browser · Nothing uploaded
- Age calculatorYears, months, and days from a birthdate to today.Runs in your browser · Nothing uploaded
- BMI calculatorHeight and weight to BMI and a WHO adult label. Not medical advice.Runs in your browser · Nothing uploaded
- Temperature converterCelsius, Fahrenheit, and Kelvin: nothing else on the page.Runs in your browser · Nothing uploaded
- Aspect ratio calculatorFind a ratio from width and height, or scale to a new size.Runs in your browser · Nothing uploaded
About Calculators
Most calculator sites wrap a multiply in ads and a signup wall. I kept the jobs I actually open: units and temperature, how far apart two dates are, age from a birthdate, a BMI number, two time zones, and the three percentage questions people mix up.
Tip, salary, mortgage, and tax tools moved to Finance. Percentage stays here as general math.
Whatever you type stays in the tab. Close the page and it's gone unless you copied it.
Tools in this category
Timezone converter
Timezone converter shows the current time in two zones and how far apart they are.
Percentage calculator
Percentage calculator is three boxes: what's X% of Y, X is what % of Y, and the change from A to B.
Date difference
Date difference is two calendar dates → years, months, days, and a total day count.
Age calculator
Age calculator takes a birthdate and counts years, months, and days to today.
BMI calculator
BMI calculator is height and weight into kg/m² with WHO adult labels.
Temperature converter
Temperature converter is Celsius, Fahrenheit, and Kelvin with nothing else in the way.
Aspect ratio calculator
Aspect ratio reduces a width and height to a ratio, or scales a ratio (with presets) to a new width or height. Results are rounded to whole pixels.
Common questions
Where did the tip and govt salary calculators go?
They live under Finance now, with redirects from the old /calculators/ URLs.
Why is temperature special in the unit converter?
Because 0 °C isn't 0 °F. You can't multiply by a constant and be done.
Does the timezone tool use my live clock?
Yes: the browser’s current time, converted.
Why these tools don't upload your files
There is no server to upload to. Each page is a static file, and the work happens in your browser. Your file is read from disk into memory, processed, and handed back as a download. Once the page has loaded you can disconnect from the network and it keeps working. The longer explanation