Free Unit Conversions Calculators

Unit Converter | Length, Weight & More

Convert between units of length, weight, temperature, volume, and more.

Number Base Converter | Binary, Hex

Convert numbers between binary, octal, decimal, and hexadecimal bases.

Speed Converter | mph, km/h, m/s

Convert between mph, km/h, m/s, knots, and feet per second.

Temperature Converter | °C, °F, K

Convert between Celsius, Fahrenheit, Kelvin, and Rankine temperature scales.

Energy Converter | Joules, kWh, BTU & Calories

Convert between 15 energy units: joules, kJ, MJ, GJ, Wh, kWh, MWh, cal, kcal, BTU, therm, ft·lb, eV, keV, MeV. Live results organized by category with smart formatting and NIST-sourced conversion factors.

Pressure Unit Converter

Convert between Pascal, psi, atm, bar, mmHg, and torr pressure units.

Data Storage Converter | Bytes, KB, MB, GB & TB

Convert between bits, bytes, KB, MB, GB, TB, PB and binary KiB, MiB, GiB, TiB units. Explains the 1 TB = 931 GB discrepancy between SI and IEC standards.

Fuel Efficiency Converter | All Units

Convert fuel efficiency between L/100km, MPG US, MPG UK, km/L, gal/100mi, and mi/L simultaneously. Includes efficiency rating and vehicle class comparison.

Angle Converter | Degrees, Radians, Gradians & More

Convert angles between degrees, radians, gradians, turns, arcminutes, arcseconds, and milliradians. Includes DMS mode and a visual angle display.

Power Unit Converter | Watts & HP

Convert between watts, kilowatts, horsepower, BTU/h, and other power units.

Shoe Size Calculator | US, UK, EU & International Size Conversion

Convert shoe sizes between US, UK, EU, Japanese, Mexican, and Brazilian sizing systems for men, women, and kids. Enter foot length in inches or centimeters for a precise size recommendation, or convert from any known size system to all others including width guidance.

Ring Size Calculator | Find Your Ring Size from Finger Measurements

Find your exact ring size from finger circumference or diameter in millimeters or inches. Converts between US/Canada, UK/Australia/South Africa, EU/ISO, and Asian sizing systems. Includes a printable paper ring sizer template and resizing guidance by metal type.