🔥 Most Popular
Length Converter
Convert between miles, kilometers, feet, meters, inches, centimeters, yards, and more. Covers both US customary and metric units. The most searched unit conversion category in the United States.
Unit Converters
Free Unit Converters
Convert between any units instantly — miles to km, Celsius to Fahrenheit, lbs to kg, inches to cm, gallons to liters, and 200+ more. All converters are free, accurate, and work on any device.
Converter Categories
Pick a category or jump straight to a specific conversion
Top Search
Temperature Converter
Convert Celsius to Fahrenheit, Fahrenheit to Celsius, and Kelvin. "Celsius to Fahrenheit" is one of the highest-volume conversion searches in the US.
Popular
Weight Converter
Convert pounds to kilograms, kilograms to pounds, ounces to grams, stones to lbs, and all common weight units.
Popular
Volume Converter
Convert gallons to liters, cups to milliliters, fluid ounces to liters, quarts to liters, and all liquid/volume units.
Popular
Speed Converter
Convert mph to km/h, km/h to mph, knots to mph, meters per second to km/h, and all speed units.
Popular
Area Converter
Convert acres to square feet, square meters to square feet, hectares to acres, and all area units.
High Volume
Currency Converter
Convert USD to EUR, GBP, CAD, AUD, MXN, JPY, and 150+ currencies with live exchange rates.
Useful
Energy Converter
Convert joules, calories, kilowatt-hours, BTU, and other energy units used in science, cooking, and physics.
Useful
Pressure Converter
Convert PSI to bar, atmospheres to pascals, kPa to psi, and other pressure units for automotive, science, and weather.
Trending
Data Storage Converter
Convert between bytes, kilobytes, megabytes, gigabytes, terabytes, and petabytes. Essential for tech and cloud storage comparisons.
All Unit Converters
Browse the complete list of free conversion tools
Length Converter
miles, km, feet, meters, inches, cm, yards, mm
Weight Converter
pounds, kg, ounces, grams, stones, tons
Temperature Converter
Celsius, Fahrenheit, Kelvin, Rankine
Volume Converter
gallons, liters, cups, fl oz, pints, quarts, mL
Speed Converter
mph, km/h, m/s, knots, Mach
Area Converter
acres, sq ft, sq m, sq km, hectares, sq miles
Currency Converter
USD, EUR, GBP, CAD, AUD, JPY, MXN + 150 more
Energy Converter
joules, calories, kWh, BTU, electron-volts
Pressure Converter
PSI, bar, atm, Pa, kPa, mmHg, torr
Power Converter
watts, kilowatts, horsepower, BTU/hr
Data Storage Converter
bytes, KB, MB, GB, TB, PB
Time Converter
seconds, minutes, hours, days, weeks, years
Fuel Economy Converter
MPG to L/100km, km/L, MPG (UK) vs MPG (US)
Angle Converter
degrees, radians, gradians, arcminutes
Miles to Kilometers
Quick mi → km with reference table
Celsius to Fahrenheit
°C → °F with common temperature reference
Pounds to Kilograms
lbs → kg with weight reference table
Inches to Centimeters
in → cm · includes height conversion chart
Gallons to Liters
US & UK gallons to liters conversion
Feet to Meters
ft → m and meters to feet converter
Conversion Reference Tables
Quick-reference values for the most searched conversions
| Miles (mi) | Kilometers (km) | Feet (ft) | Meters (m) | Inches (in) | Centimeters (cm) |
|---|---|---|---|---|---|
| 0.1 mi | 0.161 km | 528 ft | 160.9 m | 6,336 in | 16,093 cm |
| 0.5 mi | 0.805 km | 2,640 ft | 804.7 m | 31,680 in | 80,467 cm |
| 1 mi | 1.609 km | 5,280 ft | 1,609 m | 63,360 in | 160,934 cm |
| 5 mi | 8.047 km | 26,400 ft | 8,047 m | — | — |
| 10 mi | 16.093 km | 52,800 ft | 16,093 m | — | — |
| 26.2 mi (marathon) | 42.195 km | 138,336 ft | 42,195 m | — | — |
| 100 mi | 160.934 km | — | — | — | — |
| Pounds (lbs) | Kilograms (kg) | Ounces (oz) | Grams (g) | Stones (st) |
|---|---|---|---|---|
| 1 lb | 0.454 kg | 16 oz | 453.6 g | 0.071 st |
| 5 lbs | 2.268 kg | 80 oz | 2,268 g | 0.357 st |
| 50 lbs | 22.68 kg | 800 oz | 22,680 g | 3.571 st |
| 100 lbs | 45.36 kg | — | — | 7.143 st |
| 150 lbs | 68.04 kg | — | — | 10.71 st |
| 200 lbs | 90.72 kg | — | — | 14.29 st |
| Description | Celsius (°C) | Fahrenheit (°F) | Kelvin (K) | Formula |
|---|---|---|---|---|
| Absolute zero | −273.15°C | −459.67°F | 0 K | °F = (°C × 9/5) + 32 °C = (°F − 32) × 5/9 K = °C + 273.15 |
| Water freezes | 0°C | 32°F | 273.15 K | |
| Body temperature | 37°C | 98.6°F | 310.15 K | |
| Room temperature | 20°C | 68°F | 293.15 K | |
| Hot summer day | 35°C | 95°F | 308.15 K | |
| Oven (baking) | 180°C | 356°F | 453.15 K | |
| Water boils | 100°C | 212°F | 373.15 K |
| US Gallons | Liters (L) | Quarts (qt) | Pints (pt) | Cups | Fluid Oz |
|---|---|---|---|---|---|
| 1 gal | 3.785 L | 4 qt | 8 pt | 16 cups | 128 fl oz |
| 2 gal | 7.571 L | 8 qt | 16 pt | 32 cups | 256 fl oz |
| 5 gal | 18.93 L | 20 qt | 40 pt | 80 cups | 640 fl oz |
| 10 gal | 37.85 L | 40 qt | — | — | — |
| 1 cup | 0.2366 L | 0.25 qt | 0.5 pt | 1 cup | 8 fl oz |
| MPH | km/h (kph) | m/s | Knots | Typical Context |
|---|---|---|---|---|
| 25 mph | 40.2 km/h | 11.2 m/s | 21.7 kn | Residential speed limit |
| 55 mph | 88.5 km/h | 24.6 m/s | 47.8 kn | Rural highway |
| 60 mph | 96.6 km/h | 26.8 m/s | 52.1 kn | Standard highway |
| 70 mph | 112.7 km/h | 31.3 m/s | 60.8 kn | US Interstate |
| 80 mph | 128.7 km/h | 35.8 m/s | 69.5 kn | German Autobahn avg |
| 100 mph | 160.9 km/h | 44.7 m/s | 86.9 kn | — |
Find the Right Converter for Your Question
Whether you're converting recipe measurements, checking tire pressure, comparing international speeds, or doing homework — our free unit converters have you covered. Browse by common question below.
Length & Distance
How many km in a mile? How many cm in an inch? How many meters in a foot? 5 feet 9 inches to cm How many miles is 5km? Yards to meters converter Millimeters to inches chart How long is a marathon in miles?Unit Conversion FAQs
Answers to the most commonly searched conversion questions
How do you convert Celsius to Fahrenheit?
Formula: °F = (°C × 9/5) + 32. Key references: 0°C = 32°F (freezing), 20°C = 68°F (room temp), 37°C = 98.6°F (body temp), 100°C = 212°F (boiling). For reverse: °C = (°F − 32) × 5/9. Use our Celsius to Fahrenheit converter for any value instantly.
How many kilometers are in a mile?
1 mile = 1.60934 kilometers. To convert miles to km, multiply by 1.60934. To convert km to miles, multiply by 0.62137. Common: 5K race = 3.107 miles, a marathon (26.2 mi) = 42.195 km. Use our miles to km converter for any distance.
How do you convert pounds to kilograms?
1 lb = 0.453592 kg. To convert lbs to kg, multiply by 0.453592. To convert kg to lbs, multiply by 2.20462. Examples: 150 lbs = 68.04 kg, 200 lbs = 90.72 kg. Use our pounds to kg converter for a full conversion chart.
How many centimeters are in an inch?
1 inch = 2.54 centimeters (exact). To convert inches to cm, multiply by 2.54. For height: 5'9" = 175.26 cm, 6'0" = 182.88 cm. Use our inches to cm converter which includes a full height conversion chart.
How many liters are in a gallon?
1 US gallon = 3.78541 liters. Note: 1 Imperial (UK) gallon = 4.54609 liters — be sure to check which gallon is being referenced. To convert US gallons to liters, multiply by 3.78541. Use our gallons to liters converter.
How do you convert mph to km/h?
1 mph = 1.60934 km/h. To convert mph to kph, multiply by 1.60934. To convert kph to mph, multiply by 0.62137. Examples: 60 mph = 96.56 km/h, 100 kph = 62.14 mph. Use our mph to kph converter.
How many square feet are in an acre?
1 acre = 43,560 square feet. Also: 1 acre = 4,047 square meters = 0.4047 hectares = 4,840 square yards. A standard American football field (without end zones) is about 1 acre. Use our acres to square feet converter.
What is the difference between US and Imperial (UK) units?
The main differences: Gallons — 1 US gallon = 3.785 L vs 1 Imperial gallon = 4.546 L. Fluid ounces — 1 US fl oz = 29.57 mL vs 1 UK fl oz = 28.41 mL. Tons — 1 US ton = 2,000 lbs vs 1 UK long ton = 2,240 lbs. Length, weight, and temperature units are identical between US and UK.
About Our Unit Converters
The United States is one of only three countries (alongside Myanmar and Liberia) still using the US customary system rather than the metric system for everyday measurements. This means Americans frequently need to convert between US units (miles, pounds, Fahrenheit, gallons) and metric units (kilometers, kilograms, Celsius, liters) — especially for travel, science, cooking, and international commerce.
All conversion factors used on this site are based on exact international standards. The inch to centimeter conversion (1 in = 2.54 cm exactly) was internationally standardized in 1959. The mile to kilometer conversion uses the exact value of 1 mi = 1.609344 km. Temperature conversions use the exact ITS-90 scale definitions.
Our converters support both directions simultaneously — enter a value in either field and the opposite updates instantly. All calculators are mobile-optimized and work without an internet connection once loaded.