Free Online Converters

Convert length, weight, temperature, speed, area, volume, and data sizes with free online converters. Accurate constants, mobile-friendly inputs.

All free unit converters

11 free tools — no signup

Length Converter

Convert meters, feet, inches, miles, and more.

Weight Converter

Convert kg, lb, oz, g, and more weight units.

Temperature Converter

Convert Celsius, Fahrenheit, and Kelvin.

Speed Converter

Convert mph, km/h, m/s, and knots.

Area Converter

Convert m², acres, hectares, and ft².

Volume Converter

Convert liters, gallons, ml, and cups.

Data Storage Converter

Convert KB, MB, GB, TB, bits, and bytes.

Time Unit Converter

Convert seconds, minutes, hours, and days.

Roman Numerals Converter

New

Convert Roman numerals ↔ numbers.

XML to JSON

New

Convert XML into JSON structures.

CSV to XML

New

Convert CSV spreadsheets to XML.

FAQ

Are these unit converters really free?

Yes. Every tool in this category is free to use with no account and no paywall. Processing runs in your browser whenever the tool supports client-side workflows.

How accurate are the conversions?

We use standard conversion factors. Results are rounded for readability; use more decimals when precision matters.