Free Unit Converter Online - Length, Weight, Volume & Speed
Convert between units in real time. Pick a category, enter a value, and see the result instantly.
Usage Examples
Click any example to load it into the converter
1 meter to feet
1 m = 3.28 ft
1 mile in feet to meters
5280 ft = 1609.34 m
1 kilogram to pounds
1 kg = 2.20 lb
150 pounds to kilograms
150 lb = 68.04 kg
1 US gallon to liters
1 gal = 3.79 L
100 km/h to mph
100 km/h = 62.14 mph
How to Use Unit Converter
Select a Category
Choose Length, Weight, Volume, or Speed from the tabs above. The unit dropdowns update automatically.
Enter a Value and Choose Units
Type a number in the "From" field and pick your source and target units. The result updates in real time.
Copy or Swap
Use the Swap button (⇄) to exchange From and To units. Click the copy button to grab the converted value.
Frequently Asked Questions
Basics
What units are supported?
Length: meter (m), kilometer (km), mile (mi), foot (ft), inch (in), yard (yd). Weight: kilogram (kg), gram (g), pound (lb), ounce (oz). Volume: liter (L), milliliter (mL), US gallon (gal), US quart (qt), US cup. Speed: meters per second (m/s), kilometers per hour (km/h), miles per hour (mph), knots. All conversions use standard international factors accurate to at least 6 decimal places.
How accurate are the conversions?
All conversions in this unit converter use standard SI-defined factors accurate to at least 6 decimal places. For example, 1 mile equals exactly 1609.344 meters, and 1 pound equals exactly 0.45359237 kilograms by international agreement. You can adjust the displayed precision from 0 to 4 decimal places using the dropdown above the converter. Internally, calculations use full JavaScript floating-point precision before rounding to your selected number of decimal places for display.
Can I convert between categories?
No — you can only convert units within the same measurement category. Length converts to length (meters to feet), weight to weight (kilograms to pounds), and so on. Converting between categories — like meters to kilograms — is physically meaningless because they measure fundamentally different quantities. To switch categories, click the Length, Weight, Volume, or Speed tabs at the top of this unit converter. The unit dropdowns update to show the appropriate options for each category.
Common Conversions
How many feet in a meter?
1 meter equals exactly 3.28084 feet. This is the standard SI-to-imperial length conversion used in engineering and construction worldwide. To convert any meter value to feet, multiply by 3.28084. This unit converter calculates it instantly — just select meter as the source unit and foot as the target unit, enter your value, and the result appears in real time with your chosen decimal precision.
How many kilograms in a pound?
1 pound equals 0.45359237 kilograms (exactly, by international definition). Conversely, 1 kilogram equals 2.20462 pounds. The pound is the primary weight unit in the United States, while most of the world uses kilograms. This unit converter handles the conversion in both directions — select lb as the source or kg, enter your value, and see the equivalent in the other unit instantly. You can also use the Swap button (⇄) to reverse the direction.
How do I convert km/h to mph?
To convert kilometers per hour (km/h) to miles per hour (mph), multiply by 0.621371. For a quick mental estimate, divide the km/h value by 1.6. For example, 100 km/h divided by 1.6 is approximately 62.5 mph (the exact conversion is 62.14 mph). This unit converter handles the calculation precisely — select km/h as the source, mph as the target, and the result updates as you type. The formula is: mph = km/h × 0.621371 or equivalently mph = km/h ÷ 1.609344.
How many liters in a gallon?
1 US gallon equals exactly 3.78541 liters. Note that this unit converter uses US liquid gallons — UK (imperial) gallons are different at 4.54609 liters per gallon. The US gallon is the standard in American fuel economy ratings, cooking measurements, and liquid packaging. Select gallon as the source and liter as the target to convert. For quick reference: a typical 2-liter soda bottle holds approximately 0.53 US gallons, and a 5-gallon water jug holds about 18.93 liters.