The Complete Unit Conversion Guide: Length, Weight, Volume & More

Metric (SI) vs. Imperial: Two Systems, One World

The metric system (International System of Units, SI) is used by every country except the US, Liberia, and Myanmar for everyday measurement. Imperial (US Customary) units remain dominant in the US for distance, weight, volume, and temperature. Developers building global apps need to handle both — often converting between them. Here's the complete reference.

Length / Distance

1 inch = 2.54 cm (exact, by definition)
1 foot = 0.3048 meters
1 mile = 1.609344 km
1 meter = 3.28084 feet
1 kilometer = 0.621371 miles

Common references: an American football field is 100 yards (91.44 m). A marathon is 42.195 km or 26.2 miles.

Weight / Mass

1 ounce = 28.3495 grams
1 pound = 0.453592 kg
1 kg = 2.20462 pounds
1 stone (UK) = 14 pounds (6.35029 kg)
1 metric ton = 1,000 kg ≈ 2,204.62 pounds

Volume

1 US gallon = 3.78541 liters
1 UK gallon = 4.54609 liters (different from US gallon!)
1 US fluid ounce = 29.5735 milliliters
1 liter = 33.814 US fluid ounces
1 cup (US) = 236.588 milliliters

Watch out: US and UK gallons are different. A UK gallon is about 20% larger than a US gallon. This matters for fuel economy comparisons.

Temperature

°F = (°C × 9/5) + 32
°C = (°F − 32) × 5/9
K = °C + 273.15

Key reference points: water freezes at 0°C / 32°F / 273.15K. Water boils at 100°C / 212°F / 373.15K. Human body temperature: 37°C / 98.6°F.

Speed

1 mph = 1.60934 km/h
1 km/h = 0.621371 mph
1 knot = 1.852 km/h = 1.15078 mph
1 m/s = 3.6 km/h = 2.23694 mph

Area

1 square foot = 0.092903 square meters
1 acre = 4,046.86 square meters = 0.404686 hectares
1 hectare = 2.47105 acres
1 square mile = 2.58999 square km

Why Browser-Based Conversion Beats Manual Calculation

Manual conversion requires remembering formulas, checking whether you're using US or UK gallons, and avoiding off-by-one errors in decimal places. A unit converter handles all of this: pick your input unit, pick your output unit, type the value, and get the result — with the exact conversion factor applied.

Convert Units Instantly

Use ToolsVito's Unit Converter to convert between units of length, weight, volume, area, speed, temperature, pressure, energy, power, and data — with live results as you type. All in your browser.