Convert units: length (meters, feet, miles), weight (kg, pounds), temperature (Celsius, Fahrenheit, Kelvin), speed, volume, area, time, data size.
Use this free online Unit Converter directly in your browser. No signup required, no data leaves your device. Part of Utilier — a collection of 133+ developer utilities.
What is Unit Converter (Length, Weight, Temperature, Speed, Volume)?
Unit converter transforms measurements between different unit systems — metric (meters, kilograms, Celsius), imperial (feet, pounds, Fahrenheit), and scientific (Kelvin, parsecs, light-years). Convert length (meters ↔ feet ↔ miles), weight/mass (kilograms ↔ pounds ↔ ounces), temperature (Celsius ↔ Fahrenheit ↔ Kelvin), speed (km/h ↔ mph ↔ m/s), volume (liters ↔ gallons ↔ cups), area (m² ↔ acres ↔ hectares), time (seconds ↔ hours ↔ days), and data size (bytes ↔ KB ↔ MB ↔ GB). Instant conversion with real-time results, precision to 10 decimal places, and support for 100+ units across 15 categories. Useful for cooking (cups to ml), travel (km to miles), science (Celsius to Kelvin), or engineering (PSI to bar).
Multi-category support: Length (mm, cm, m, km, inch, foot, yard, mile), Weight (mg, g, kg, oz, lb, ton), Temperature (°C, °F, K), Speed (m/s, km/h, mph, knots), Volume (ml, L, cup, gallon, oz), Area (m², acre, hectare), Time (ms, s, min, h, day), Data (byte, KB, MB, GB, TB), Pressure (Pa, bar, PSI), Energy (J, cal, kWh).
Bi-directional conversion: Convert in both directions instantly. Example: 1 km = 0.621 miles, or 1 mile = 1.609 km. No need to switch units manually.
High precision: Results to 10 decimal places for scientific accuracy. Example: π meters = 3.1415926536 meters. Handles very small (nanometers) and very large (light-years) values.
Real-time conversion: Type value → see instant conversion. No button clicks. Example: type '100' in meters → see '328.084 feet' immediately.
Common conversions: Pre-configured for common use cases: cooking (cups ↔ ml), travel (km ↔ miles), height (feet ↔ cm), weight (lbs ↔ kg), temperature (°C ↔ °F).
Why use unit converter?
Remembering conversion formulas (1 mile = 1.609 km, °F = °C × 9/5 + 32) is tedious. This tool converts instantly with high precision.
Avoid conversion errors: Manual calculation is error-prone (1 gallon = 3.785 liters, not 4). Tool ensures accuracy. Critical for cooking, science, engineering.
International communication: US uses imperial (miles, pounds, Fahrenheit), rest of world uses metric (km, kg, Celsius). Convert for international recipes, travel, or documentation.
Cooking and recipes: Convert cups to ml (1 cup = 237 ml), tablespoons to grams, Fahrenheit to Celsius. Essential for international recipes or metric kitchens.
Science and engineering: Convert temperature (25°C = 298.15 K), pressure (1 bar = 14.5 PSI), energy (1 kWh = 3.6 MJ). High precision for calculations.
Data storage: Convert file sizes (1 GB = 1024 MB or 1000 MB?). Binary (1024) vs decimal (1000) units. Tool shows both.
When to use unit converter
Use whenever you need to convert measurements between different unit systems.
Converting recipe measurements (cups to ml, tablespoons to grams, Fahrenheit to Celsius).
Travel planning (miles to km, mph to km/h, gallons to liters for fuel).
Scientific calculations (Celsius to Kelvin, joules to calories, pascals to bar).
Height and weight conversion (feet/inches to cm, pounds to kg, BMI calculations).
Real estate (square feet to square meters, acres to hectares).
Data storage (bytes to KB/MB/GB, binary vs decimal units).
Engineering (PSI to bar, horsepower to watts, torque units).
How to use unit converter
Select units, enter value, see instant conversion.
Choose category: Select: Length, Weight, Temperature, Speed, Volume, Area, Time, Data Size, Pressure, Energy. Each category has relevant units.
Select 'from' unit: Choose source unit: meters, kilograms, Celsius, etc. This is the unit you're converting FROM.
Select 'to' unit: Choose target unit: feet, pounds, Fahrenheit, etc. This is the unit you're converting TO.
Enter value: Type value to convert (e.g., 100). Tool converts instantly (no button click needed). Real-time results.
View result: See conversion result with high precision (10 decimal places). Example: 100 meters = 328.0839895013123 feet.
Swap units (optional): Click swap button to reverse conversion direction. Example: meters → feet becomes feet → meters.
Copy result: Copy result to clipboard for use in documents, spreadsheets, or calculations.
Key features
15+ categories: Length, Weight, Temperature, Speed, Volume, Area, Time, Data Size, Pressure, Energy, Force, Power, Frequency, Angle, Density.
100+ units: Metric (SI), imperial, US customary, scientific. Example: Length has 20+ units (mm, cm, m, km, inch, foot, yard, mile, nautical mile, AU, light-year).
Bi-directional: Convert both ways instantly. Example: km ↔ miles, °C ↔ °F, lbs ↔ kg. No need to switch manually.
High precision: 10 decimal places for scientific accuracy. Handles very small (nanometers) and very large (light-years) values.
Real-time conversion: Type value → instant result. No button clicks. Updates as you type.
Common conversions: Quick access: km ↔ miles, lbs ↔ kg, °C ↔ °F, cups ↔ ml, ft ↔ m.
Binary vs decimal: Data size: binary (1 KB = 1024 bytes) vs decimal (1 KB = 1000 bytes). Tool shows both.
Common use cases
Recipe conversion (cups to ml): 1 cup flour = 237 ml (US cup) or 250 ml (metric cup). Tool shows both. Also: tablespoons to grams, Fahrenheit to Celsius for oven temp.
Travel (miles to km): 100 miles = 160.934 km. Speed limit: 55 mph = 88.5 km/h. Fuel economy: 30 mpg = 7.84 L/100km (inverse).
Height conversion (feet to cm): 6 feet = 182.88 cm. Or 5'10" = 177.8 cm. Common for international forms or medical records.
Weight conversion (lbs to kg): 150 pounds = 68.04 kg. Or 70 kg = 154.32 lbs. Used for luggage limits, fitness tracking, medical records.
Temperature (Celsius to Fahrenheit): 25°C = 77°F (room temperature). Or 100°C = 212°F (boiling water). Formula: °F = °C × 9/5 + 32.
Data size (GB to MB): 1 GB = 1024 MB (binary, GiB) or 1000 MB (decimal, GB). Hard drive: 1 TB = 1000 GB (manufacturer) or 931 GiB (OS shows).
Examples
Common unit conversions.
Recipe: cups to milliliters
2 cups (US)
473.176 ml (or 474 ml rounded)
1 US cup = 236.588 ml. Metric cup = 250 ml (different). For baking precision, use grams instead of cups.
Travel: miles to kilometers
100 miles
160.934 km
1 mile = 1.60934 km (exact). Speed: 55 mph = 88.5 km/h. Reverse: 100 km = 62.137 miles.
Height: feet and inches to cm
5 feet 10 inches
177.8 cm (5 × 30.48 + 10 × 2.54)
1 foot = 30.48 cm, 1 inch = 2.54 cm. Reverse: 180 cm = 5 feet 10.87 inches.
Weight: pounds to kilograms
150 lbs
68.0389 kg
1 lb = 0.453592 kg. Reverse: 70 kg = 154.324 lbs. Used for luggage limits (50 lbs = 22.68 kg).
1 meter = 100 cm = 3.28084 feet = 39.3701 inches. 1 mile = 1.60934 km. 1 inch = 2.54 cm (exact). Metric: mm, cm, m, km. Imperial: inch, foot, yard, mile. Scientific: AU, light-year, parsec.
Weight/Mass
1 kg = 1000 g = 2.20462 pounds. 1 pound = 16 oz = 453.592 g. 1 ton (metric) = 1000 kg. 1 ton (US) = 2000 lbs = 907.185 kg. Metric: mg, g, kg, ton. Imperial: oz, lb, ton.
Temperature
Celsius: 0°C (water freezes), 100°C (water boils). Fahrenheit: 32°F (freezes), 212°F (boils). Kelvin: 273.15 K (0°C), 373.15 K (100°C). Formulas: °F = °C × 9/5 + 32, K = °C + 273.15.
Speed
1 m/s = 3.6 km/h = 2.23694 mph. 1 mph = 1.60934 km/h. 1 knot = 1.852 km/h (nautical mile per hour). Units: m/s, km/h, mph, knots, ft/s.
Volume
1 liter = 1000 ml = 33.814 oz (US) = 1.057 quarts (US). 1 gallon (US) = 3.78541 L. 1 gallon (UK) = 4.54609 L. 1 cup (US) = 237 ml. 1 cup (metric) = 250 ml. Units: ml, L, oz, cup, pint, quart, gallon.
Area
1 m² = 10.7639 ft². 1 acre = 4046.86 m² = 0.404686 hectare. 1 hectare = 10,000 m² = 2.47105 acres. Units: mm², cm², m², km², in², ft², yd², acre, hectare.
Confusing US cups (237 ml) with metric cups (250 ml) in recipes
Why it happens: US cup = 236.588 ml, metric cup = 250 ml (5% difference). Using wrong cup in baking affects results (too much/little flour). Common when using international recipes.
How to avoid it: Check recipe source: US recipes use 237 ml cups, Australian/metric use 250 ml. For precision, use weight (grams) instead of volume (cups).
Using wrong temperature formula (forgetting +32 for Celsius to Fahrenheit)
Why it happens: Correct: °F = °C × 9/5 + 32. Wrong: °F = °C × 9/5 (missing +32). Example: 25°C → 45°F (wrong) vs 77°F (correct). Off by 32 degrees.
How to avoid it: Remember: °F = °C × 1.8 + 32. Or use tool. Reverse: °C = (°F - 32) / 1.8. Kelvin: K = °C + 273.15 (no multiplication).
Confusing binary (1024) and decimal (1000) in data sizes
Why it happens: Hard drive manufacturers use decimal (1 TB = 1,000,000,000,000 bytes). OS uses binary (1 TiB = 1,099,511,627,776 bytes). 1 TB drive shows as ~931 GiB in OS (~9% difference).
How to avoid it: Use IEC units: KiB, MiB, GiB (binary, 1024). Or SI units: KB, MB, GB (decimal, 1000). Tool shows both. Hard drives: decimal. RAM: binary.
Mixing US and UK gallons (20% difference)
Why it happens: US gallon = 3.785 L. UK (imperial) gallon = 4.546 L (20% larger). Using wrong gallon in fuel calculations gives wrong MPG or range.
How to avoid it: Specify US or UK gallon. Fuel economy: US uses MPG (miles per gallon), rest of world uses L/100km. 30 MPG (US) = 7.84 L/100km.
Not converting Celsius to Kelvin correctly for scientific calculations
Why it happens: Kelvin is absolute scale (0 K = -273.15°C, no negative). Celsius: K = °C + 273.15 (NOT × 273.15). Example: 25°C = 298.15 K, not 6828.75 K. Common in gas law calculations.
How to avoid it: Kelvin: K = °C + 273.15 (addition, not multiplication). Kelvin scale: 0 K (absolute zero), 273.15 K (water freezes), 373.15 K (water boils).
Frequently asked questions
What is the difference between US cups and metric cups?
US cup = 236.588 ml. Metric cup = 250 ml (5% larger). Use weight (grams) for precision in baking. Check recipe source (US vs metric).
How do I convert Celsius to Fahrenheit?
°F = °C × 9/5 + 32. Or °F = °C × 1.8 + 32. Example: 25°C = 77°F. Reverse: °C = (°F - 32) / 1.8. Freezing: 0°C = 32°F.
What is the difference between 1 KB and 1 KiB?
1 KB (kilobyte) = 1000 bytes (decimal, SI). 1 KiB (kibibyte) = 1024 bytes (binary, IEC). Hard drives use KB, RAM/OS use KiB. 1 GB drive = ~931 MiB.
How many kilometers in a mile?
1 mile = 1.60934 km. Reverse: 1 km = 0.621371 miles. Speed: 60 mph = 96.56 km/h. Marathon: 26.2 miles = 42.195 km.
How do I convert pounds to kilograms?
1 lb = 0.453592 kg. Example: 150 lbs = 68.04 kg. Reverse: 1 kg = 2.20462 lbs. Luggage: 50 lbs = 22.68 kg.
What is the difference between US and UK gallons?
US gallon = 3.785 L. UK (imperial) gallon = 4.546 L (20% larger). Always specify US or UK. Fuel economy: use MPG (US) or L/100km (metric).
How do I convert Celsius to Kelvin?
K = °C + 273.15 (addition, not multiplication). Example: 25°C = 298.15 K. Absolute zero: 0 K = -273.15°C. No negative Kelvin.