Convert between length, weight, volume, and temperature units instantly
Whether you're cooking a recipe that uses cups but your scale measures grams, planning a road trip between countries with different unit systems, or converting a temperature for a science project, our free Unit Converter handles it all in real time.
The tool supports four essential categories: Length (millimeters to miles), Weight (milligrams to stone), Volume (milliliters to gallons), and Temperature (Celsius, Fahrenheit, Kelvin). Each category uses a two-way interface — change either the "from" or "to" value and the other updates instantly. You can also swap units independently using the dropdowns without losing your entered value.
All conversions happen entirely in your browser using precise conversion factors and direct formulas for temperature (no approximations). No login, no ads, and no data sent to any server. Just type a number and get an accurate result in your chosen unit.
Conversions use up to 8 significant digits of precision based on standard conversion factors (e.g., 1 inch = 0.0254 meters exactly). Temperature uses the mathematically exact formulas: °F = °C × 9/5 + 32 and K = °C + 273.15.
Length: mm, cm, m, km, in, ft, yd, mi. Weight: mg, g, kg, oz, lb, st. Volume: ml, l, fl oz, cup, pt, qt, gal. Temperature: Celsius, Fahrenheit, Kelvin.
Length, weight, and volume conversions are linear (multiply by a factor), but temperature scales have different zero points, so direct formulas are needed rather than simple multiplication.
Yes — both the "From" and "To" fields are fully interactive. Type in either field and the other updates automatically. This makes it easy to reverse a conversion without retyping.
Once the page is loaded, all conversion logic runs in your browser with no network requests, so it works without an active internet connection.