Convert Any Unit Instantly
The world runs on two measurement systems — metric (used by 95% of the world) and imperial (used primarily in the US, Liberia, and Myanmar). Whether you're following a European recipe, reading a scientific paper, buying materials from an international supplier, or just trying to understand a weather report in Celsius, unit conversion is a daily necessity.
Our converter handles seven categories: length (miles, km, feet, meters, inches, cm, mm), weight (lbs, kg, oz, grams, stones), temperature (°F, °C, Kelvin), volume (gallons, liters, cups, ml, fl oz), speed (mph, km/h, m/s, knots), area (sq ft, sq m, acres, hectares), and data (bytes, KB, MB, GB, TB).
Most-searched conversions: 1 mile = 1.609 km. 1 kg = 2.205 lbs. °F to °C: subtract 32, multiply by 5/9. 1 gallon = 3.785 liters. 1 inch = 2.54 cm. 1 foot = 30.48 cm. 1 oz = 28.35 grams. 1 stone = 14 lbs = 6.35 kg.
Length Conversions
The most common conversion is between the imperial system (inches, feet, yards, miles) and the metric system (millimeters, centimeters, meters, kilometers).
Key equivalencies: 1 inch = 2.54 cm (exact). 1 foot = 12 inches = 30.48 cm. 1 yard = 3 feet = 0.9144 meters. 1 mile = 5,280 feet = 1.609344 km. 1 meter = 3.281 feet = 39.37 inches. 1 kilometer = 0.6214 miles.
Quick mental math for km to miles: Multiply by 0.6 for a rough estimate. 10 km ≈ 6 miles. 100 km ≈ 60 miles. For better accuracy, use the Fibonacci approximation: consecutive Fibonacci numbers approximate the km-to-miles ratio. 5 km ≈ 3 miles, 8 km ≈ 5 miles, 13 km ≈ 8 miles.
Height conversions: 5'0" = 152 cm. 5'4" = 163 cm. 5'8" = 173 cm. 6'0" = 183 cm. 6'4" = 193 cm. Multiply feet by 30.48 and add inches × 2.54 for exact conversion.
Weight Conversions
Key equivalencies: 1 pound (lb) = 16 ounces (oz) = 453.6 grams = 0.4536 kg. 1 kilogram = 2.205 lbs = 35.27 oz. 1 ounce = 28.35 grams. 1 stone = 14 lbs = 6.35 kg (used primarily in UK and Ireland for body weight).
Quick mental math for lbs to kg: Divide by 2.2. 150 lbs ÷ 2.2 ≈ 68 kg. For rough estimates, halve the number and subtract 10%: 150 → 75 → 75 - 7.5 = 67.5 kg. Close enough for everyday use.
Cooking conversions: Butter: 1 cup = 227g = 8 oz = 2 sticks. Flour: 1 cup = 125g. Sugar: 1 cup = 200g. These vary by ingredient because weight-per-volume differs — always use weight (grams) for precision in baking.
Precious metals use troy ounces: 1 troy oz = 31.103 grams (vs. 28.35g for regular oz). Gold and silver are always quoted in troy ounces.
Temperature Conversions
Temperature is the conversion most people struggle with because the relationship isn't a simple multiplier — it involves an offset (32°F = 0°C).
Fahrenheit to Celsius: (°F - 32) × 5/9 = °C. 72°F = (72-32) × 5/9 = 22.2°C. 32°F = 0°C (water freezes). 212°F = 100°C (water boils). 98.6°F = 37°C (body temperature). -40°F = -40°C (the one point where both scales intersect).
Celsius to Fahrenheit: (°C × 9/5) + 32 = °F. 25°C = (25 × 1.8) + 32 = 77°F.
Quick mental estimate (°C to °F): Double the Celsius value and add 30. 20°C → 40 + 30 = 70°F (actual: 68°F). 30°C → 60 + 30 = 90°F (actual: 86°F). Good enough for weather conversations.
Kelvin: Used in science. K = °C + 273.15. 0 K = -273.15°C = absolute zero (the lowest possible temperature). Room temperature ≈ 293 K. Water boils at 373 K.
Volume, Speed, Area, and Data Conversions
Volume: 1 gallon (US) = 3.785 liters = 4 quarts = 128 fl oz. 1 liter = 0.264 gallons = 33.81 fl oz = 4.227 cups. 1 cup = 236.6 ml = 8 fl oz. Note: UK/Imperial gallons are larger (4.546 liters) than US gallons — this matters for fuel economy comparisons.
Speed: 1 mph = 1.609 km/h. 1 km/h = 0.621 mph. 1 m/s = 2.237 mph = 3.6 km/h. 1 knot = 1.151 mph = 1.852 km/h. Speed of sound ≈ 767 mph = 1,235 km/h. Speed of light ≈ 670,616,629 mph.
Area: 1 sq ft = 0.0929 sq m. 1 sq m = 10.764 sq ft. 1 acre = 43,560 sq ft = 4,047 sq m. 1 hectare = 2.471 acres = 10,000 sq m. A typical American house lot is 0.1–0.5 acres.
Data storage: 1 KB = 1,024 bytes. 1 MB = 1,024 KB. 1 GB = 1,024 MB. 1 TB = 1,024 GB. Note: storage manufacturers use decimal (1 GB = 1,000,000,000 bytes) while operating systems use binary (1 GB = 1,073,741,824 bytes), which is why a "500 GB" drive shows ~465 GB in Windows.
Frequently Asked Questions
Multiply by 9/5 (or 1.8) and add 32. 25°C × 1.8 + 32 = 77°F. For a quick estimate, double the Celsius and add 30: 25 → 50 + 30 = 80°F (close enough for casual use). For exact conversion, use the full formula.
28.3495 grams in a regular (avoirdupois) ounce. For cooking, 28g per ounce is sufficiently precise. For precious metals, a troy ounce equals 31.1035 grams — about 10% more than a regular ounce.
Multiply by 0.6214. 10 km = 6.21 miles. 100 km = 62.14 miles. Quick mental trick: multiply by 6 and move the decimal (10 km × 6 = 60, move decimal = 6.0 miles). Or use Fibonacci numbers: 5 km ≈ 3 miles, 8 km ≈ 5 miles.
The US gallon (3.785 liters) and Imperial/UK gallon (4.546 liters) diverged when the US adopted the Queen Anne wine gallon in 1824, while the UK adopted the larger Imperial gallon based on the weight of water. The 20% difference matters for fuel economy — a car rated at 30 MPG in the US would be rated at 36 MPG using UK gallons.
Key conversions: 1 cup = 237 ml. 1 tablespoon = 15 ml. 1 teaspoon = 5 ml. 1 oz = 28g. For baking precision, convert volume measures to weight (grams) using ingredient-specific densities. A kitchen scale ($10–15) eliminates the need for volume-to-weight conversion entirely and produces more consistent results.
MB (megabyte, uppercase B) measures data storage — file sizes, RAM, storage capacity. Mb (megabit, lowercase b) measures data transfer speed — internet bandwidth. 1 MB = 8 Mb. A 100 Mbps internet connection downloads at approximately 12.5 MBps. ISPs advertise in Mb (bigger number); downloads show in MB.
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