Unit Conversion Calculator — Convert Length, Mass, Temperature, Area & Volume
Unit Converter Hub
Convert length, mass, temperature, area, and volume in real time
Looking for a dedicated converter? Try our Base64 Encoder, Color Converter, or browse all Conversion Tools.
Shareable Links
Every conversion updates the URL automatically, so you can bookmark or share an exact pair like Celsius to Fahrenheit with one click.
Bidirectional Fields
Type in either box and the other updates instantly, no need to pick a "direction" before you start converting.
Five Categories
Covers Length, Mass, Temperature, Area, and Volume, spanning the metric and US customary units people look up most often.
Private By Design
All math happens locally in your browser using fixed conversion factors. Your numbers never leave your device.
How to Use the Free Unit Conversion Calculator
Whether you are converting a recipe from cups to milliliters, checking a shipping weight in pounds versus kilograms, or double-checking a temperature reading, this Unit Conversion Calculator keeps every category in one place. Pick a category, choose your units, and type a value into either field — the result updates as you type.
Conversion factors are based on exact NIST and SI definitions (for example, 1 inch = 0.0254 meters and 1 pound = 0.45359237 kilograms), so results stay accurate down to small quantities. Temperature uses the standard Celsius, Fahrenheit, and Kelvin formulas rather than a simple ratio.
Unit Conversion Tips & Notes
-
Deep links work: URLs like
?category=temperature&from=celsius&to=fahrenheit&value=100load directly into the matching pair. - Swap instantly: Use the swap button to flip the "From" and "To" units and values without retyping.
- Accuracy note: Results are rounded for display and provided for general informational purposes only; consult a certified reference for regulatory, medical, or engineering-critical conversions.
- Privacy: All conversions run locally in your browser; no values you enter here are ever sent to our servers.
Frequently Asked Questions
The Unit Conversion Calculator covers five categories: Length (mm, cm, m, km, inches, feet, yards, miles), Mass (mg, g, kg, metric tons, ounces, pounds, stone), Temperature (Celsius, Fahrenheit, Kelvin), Area (m², km², ft², yd², acres, hectares), and Volume (mL, L, m³, US gallons, quarts, pints, cups, fluid ounces).
- Select a category (Length, Mass, Temperature, Area, or Volume).
- Choose your starting unit from the From dropdown.
- Choose your target unit from the To dropdown.
- Type a value in either field — the other updates instantly.
- Use the swap button to reverse the direction without retyping.
Conversion factors are based on exact NIST and SI definitions — 1 inch = exactly 0.0254 m, 1 pound = exactly 0.45359237 kg. Temperature conversions use the standard formulas rather than a fixed ratio. Results are rounded for display; for regulatory, medical, or engineering-critical use, always verify against a certified reference.
Yes. Every time you change a value, category, or unit, the URL updates automatically to reflect your selection. Copy the address bar and share or bookmark it — when opened, the unit converter loads directly into the same category, units, and value you set.
All unit conversions run entirely in your browser using fixed conversion factors baked into the page. No data you enter is ever sent to a server, which means results appear instantly and the tool works offline once the page has loaded.