Free Unit Converter Online — Length, Weight, Temperature & More
Free online unit converter for length, weight, volume, temperature, area, and speed. Metric ↔ imperial conversions in your browser, no sign-up.
Cooking from a US recipe in a metric kitchen, traveling between countries, or solving a physics problem — sooner or later you need a fast, trustworthy unit converter. Our Unit Converter handles length, weight, volume, temperature, area, and speed in one screen.
Categories and units supported
| Category | Units |
|---|---|
| Length | mm, cm, m, km, in, ft, yd, mi, nautical mi |
| Weight | mg, g, kg, t, oz, lb, stone |
| Volume | ml, l, m³, tsp, tbsp, fl oz, cup, pint, qt, gallon (US/UK) |
| Temperature | °C, °F, K |
| Area | m², km², ha, acre, ft², yd², mi² |
| Speed | m/s, km/h, mph, knot |
| Time | ms, s, min, h, day, week |
| Data | bit, byte, KB, MB, GB, TB |
The converter updates results as you type, in both directions.
Common everyday conversions
Cooking
- 1 US cup = 240 ml
- 1 UK cup = 250 ml
- 1 tablespoon = 15 ml
- 1 teaspoon = 5 ml
- 1 oz = 28.35 g (weight) — different from 1 fl oz (volume)
Body and health
- 1 ft = 30.48 cm
- 6 ft ≈ 183 cm
- 1 lb = 0.4536 kg
- 150 lb ≈ 68 kg
Driving and travel
- 60 mph ≈ 97 km/h
- 100 km/h ≈ 62 mph
- 1 mile ≈ 1.609 km
- 1 gallon (US) ≈ 3.785 l
Temperature shortcuts
- 0°C = 32°F (water freezes)
- 100°C = 212°F (water boils)
- 20°C ≈ 68°F (room temperature)
- Quick formula: °F = °C × 1.8 + 32
Fluid ounces vs. weight ounces
A frequent source of recipe disasters. Fluid ounces (fl oz) measure volume; ounces (oz) measure weight. They are not interchangeable:
- 1 fl oz of water happens to weigh ≈ 1 oz (water is the special case)
- 1 fl oz of honey weighs ≈ 1.5 oz
- 1 fl oz of flour weighs ≈ 0.55 oz
Always check whether a recipe means weight or volume — it matters most for baking.
US vs. imperial vs. metric
Three systems coexist:
- Metric — most of the world, science, medicine
- US customary — United States; gallons, pints, and cups are smaller than UK versions
- Imperial / UK — UK shipping, fuel mileage; pints and gallons are larger than US
A US gallon is 3.785 l. A UK gallon is 4.546 l. A US pint is 473 ml; a UK pint is 568 ml. Pick the right region in the converter or you'll be 20% off.
How to use the unit converter
- Open the Unit Converter
- Pick a category (length, weight, etc.)
- Choose source and target units
- Type a value — the result appears immediately
- Swap directions with one click
Conversions happen in your browser. Nothing is uploaded.
Precision and rounding
By default we show up to 6 significant digits, which covers ordinary use without messy decimals. For scientific or engineering work, copy the unrounded value or use the slider to add more digits.
For cooking, round to the nearest whole or half unit — measuring 28.349 g of butter is silly when 28 g works.
Quick conversion table for travelers
| You see | It means (approx.) |
|---|---|
| 30°C | 86°F (hot day) |
| 10°C | 50°F (jacket weather) |
| -5°C | 23°F (winter coat) |
| 100 km/h speed limit | 62 mph |
| 50 km to next city | 31 mi |
| 1 l of fuel | 0.26 US gallon |
Why use a dedicated tool over Google
Google does single conversions inline, but our Unit Converter is faster when:
- You're converting many values in one session
- You want both directions side-by-side
- You're offline (works as a PWA after first load)
- You need precise control over significant digits
- You want to avoid Google's tracking
Summary
A unit converter is one of those tools you don't think about until you need it five times in a row. Bookmark the Unit Converter for cooking, travel, fitness, and DIY — combined with the Currency Converter it covers most everyday "what is X in Y" questions.