Convert between everyday units like meters and feet, kilograms and pounds, or Celsius and Fahrenheit. Pick a category, choose what you are converting from and to, type a number, and the answer appears instantly. Everything runs in your browser.
About this unit converter
A unit converter changes a measurement from one unit into another — for example turning 10 miles into kilometers, or 70 °F into Celsius. Choose a category (length, weight/mass, temperature, area, volume or speed), pick the unit you have and the unit you want, then type your number. Most conversions are simple multiplication using exact standard factors; temperature uses formulas because the scales have different zero points. Students, cooks, travelers, engineers and DIY hobbyists all use a converter like this. It runs entirely in your browser, so nothing you type is uploaded or stored.
Frequently asked questions
- What units can I convert?
- You can convert length (meters, feet, miles and more), weight or mass (kilograms, pounds, ounces), temperature (Celsius, Fahrenheit, Kelvin), area, volume and speed. Pick a category, choose the two units, and type a number.
- Is the conversion accurate?
- Yes. It uses exact standard factors, such as 1 inch = 0.0254 meters and 1 pound = 0.45359237 kilograms, so results match official definitions. The answer is rounded for display but calculated at full precision.
- Does my data get uploaded?
- No. The converter runs entirely in your browser, so the numbers you enter never leave your device.
Where unit conversions go wrong
Most standard units rely on defined international constants rather than arbitrary measurements. For instance, the meter is officially anchored to the speed of light in a vacuum, while the kilogram is calibrated against fixed physical constants in quantum physics. When a tool changes one unit to another, it multiplies your input by a fixed conversion ratio derived from these official international agreements. Because these ratios are constant, you can convert in reverse simply by dividing the result by that same exact factor.
Temperature scales operate differently because they measure thermal energy relative to different reference points rather than starting at an absolute zero of zero. While Celsius and Fahrenheit both measure the same physical phenomenon, Fahrenheit sets the freezing point of water at thirty-two degrees and Celsius sets it at zero. Converting between them requires an offset adjustment in addition to multiplying by a fractional ratio. Kelvin shares the exact same degree interval size as Celsius but shifts its zero point to absolute zero, meaning you only need to add or subtract a fixed constant rather than multiply.
The most frequent error people make during manual conversions involves mixing up scale factors and offset values, especially with temperature or compound units like square and cubic measurements. Squaring a linear conversion factor is necessary when moving from linear dimensions to area, meaning you must square the entire ratio rather than just multiplying the original conversion factor by two. Another common pitfall is premature rounding during intermediate steps, which introduces cumulative errors into the final output. Using a digital tool avoids these calculation slips by preserving full floating-point precision throughout the entire mathematical operation.