Unit Converter
Convert length, weight, temperature, volume, area, speed, time and digital storage instantly. Type a number, pick your units, and see the result update live — no download, no signup.
| Convert | Equals |
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This page never sends what you type to a server. Every conversion is calculated locally in your browser using standard conversion factors, and nothing is stored once you leave the page.
How this unit converter works
Pick a category, then choose the units you're converting from and to. Type a number in either box and the other one updates instantly — the converter works in both directions, so you can enter a value on the "To" side just as easily as the "From" side. Use the swap button to flip the two units in one click.
Every category is converted through a common base unit (for example, meters for length or liters for volume) using standard, internationally recognized conversion factors, so results stay consistent and accurate across the whole tool.
Worked example
To convert 5 miles to kilometers, choose Length, set From to Miles and To to Kilometers, and type 5. The converter multiplies 5 by 1,609.344 (meters in one mile) to get 8,046.72 meters, then divides by 1,000, so the result is 8.04672 km.
Unit categories supported
| Category | Includes |
|---|---|
| Length | Millimeters, centimeters, meters, kilometers, inches, feet, yards, miles, nautical miles |
| Weight & mass | Milligrams, grams, kilograms, metric tons, ounces, pounds, stone, US tons |
| Temperature | Celsius, Fahrenheit, Kelvin |
| Volume | Milliliters, liters, cubic meters, teaspoons, tablespoons, fl. oz, cups, pints, quarts, gallons |
| Area | mm², cm², m², km², hectares, in², ft², yd², acres, mi² |
| Speed | Meters/second, km/h, mph, knots, feet/second |
| Time | Milliseconds, seconds, minutes, hours, days, weeks, months, years |
| Digital storage | Bits, bytes, KB, MB, GB, TB, PB (binary, 1024-based) |
Notes on specific units
- Temperature uses formulas rather than a single factor: °F = °C × 9/5 + 32 and K = °C + 273.15. Values below absolute zero are not rejected.
- Digital storage uses binary units (1 KB = 1,024 bytes). Drives and some network equipment are sold in decimal units (1 TB = 1,000,000,000,000 bytes), which is why a drive sold as 1 TB appears as about 931 GB here.
- Time uses fixed durations: a month is 30.4375 days and a year is 365.25 days (averages). That is different from calendar arithmetic with real month lengths, so use a date calculator for exact dates and ages.
- Volume units marked US are US customary units. UK imperial gallons, pints and fluid ounces are different sizes and are not included.
Method and sources
Each category is converted through a base unit (meters, kilograms, liters, square meters, meters per second, seconds and bytes), so any unit can be converted to any other in the same category. Factors such as 1 inch = 2.54 cm exactly and 1 pound = 0.45359237 kg exactly are the internationally agreed definitions. Results are calculated with JavaScript's double-precision numbers and shown rounded to up to 8 decimal places; very large or very small results are shown in scientific notation with 5 significant digits.
Sources: NIST SP 811, Guide for the Use of the International System of Units (SI), including its conversion factors appendix.
Frequently asked questions
Is this unit converter free?
Yes. It's completely free, runs in your browser, and doesn't require an account, download or payment.
How accurate are the conversions?
Conversions use standard, internationally recognized conversion factors (for example, 1 inch equals exactly 2.54 centimeters). They are calculated with double-precision numbers and shown rounded to up to 8 decimal places, which is accurate for everyday, academic and professional use.
Does this tool store or send my data anywhere?
No. Every conversion happens locally in your browser. Nothing you type is sent to a server or saved.
Can I convert between metric and imperial units?
Yes. Every category mixes metric units (meters, kilograms, liters, Celsius) with imperial or US customary units (feet, pounds, gallons, Fahrenheit) in the same dropdowns, so you can convert freely between the two systems.
Why does digital storage use 1024 instead of 1000?
File sizes on most operating systems are traditionally measured in binary units, where 1 KB = 1024 bytes rather than 1000. This converter follows that common convention for KB through PB.
Can I use this unit converter on mobile?
Yes, the converter is fully responsive and works on phones, tablets and desktop browsers.