Convert between units of length, weight, temperature, volume, area, speed, and more. Free online unit converter.
Pick a category - length, weight/mass, temperature, volume, area, speed or time - enter a value, and choose the units to convert from and to. The result updates instantly as you type. All categories work in both directions, so km to miles and miles to km use the same tool.
Values marked ≈ are rounded for readability; "=" means exact by definition.
Length: 1 km = 1000 m ≈ 0.621371 miles | 1 mile ≈ 1.60934 km | 1 ft = 30.48 cm | 1 inch = 2.54 cm | 1 yard = 0.9144 m
Weight: 1 kg = 1000 g ≈ 2.20462 lb | 1 lb ≈ 453.592 g | 1 oz ≈ 28.3495 g | 1 tonne = 1000 kg
Volume: 1 L = 1000 mL ≈ 0.264172 US gallons | 1 US gallon ≈ 3.78541 L | 1 US cup ≈ 236.588 mL | 1 tbsp = 3 tsp
Area: 1 acre = 43560 sq ft ≈ 4046.86 m² | 1 hectare = 10000 m² ≈ 2.47105 acres | 1 m² ≈ 10.7639 sq ft
Speed: 1 m/s = 3.6 km/h ≈ 2.23694 mph | 1 knot = 1.852 km/h
Temperature: 0°C = 32°F = 273.15K | 100°C = 212°F = 373.15K
India uses the metric system (kilometers, kilograms, liters, Celsius), while the United States uses US customary units (miles, pounds, gallons, Fahrenheit). Be careful with volume units: this tool uses US gallons, cups, pints and fluid ounces, which are smaller than the British imperial units of the same name - 1 US gallon is about 3.785 L, while 1 imperial gallon is 4.54609 L. If a recipe or manual comes from the UK, double-check which gallon or pint it means.
Temperature units do not scale by simple multiplication because their zero points differ. The formulas are: °F = °C x 9/5 + 32, and K = °C + 273.15. This converter also supports Rankine (°R), an absolute scale used in some engineering fields, where 0°R is absolute zero and 491.67°R = 0°C.
Q: Is this conversion calculator free?
A: Yes, it is completely free, works on mobile and desktop, and needs no sign-up.
Q: Which gallon, pint and cup does this tool use?
A: US customary units: 1 US gallon ≈ 3.78541 L, 1 US pint ≈ 473.176 mL, 1 US cup ≈ 236.588 mL. These differ from British imperial units.
Q: How are months and years converted in the time category?
A: Using average lengths: one year is 365.2425 days (31,556,952 seconds) and one month is one-twelfth of that. Calendar months vary from 28 to 31 days, so convert exact dates by days instead.
Q: How accurate are the results?
A: Conversions use standard defined or widely accepted factors (for example 1 inch is exactly 2.54 cm and 1 lb is exactly 0.45359237 kg by international definition) and are shown rounded for readability. For engineering, legal or scientific work, verify the rounding you need.
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