Convert between metric, imperial, and other units — fast & free
| Conversion | Value |
|---|---|
| 1 inch | 2.54 cm |
| 1 foot | 0.3048 m / 30.48 cm |
| 1 mile | 1.60934 km |
| 1 pound (lb) | 0.453592 kg |
| 1 ounce (oz) | 28.3495 g |
| 1 US gallon | 3.78541 L |
| 1 cup (US) | 236.588 mL |
| 0°C | 32°F / 273.15 K |
How many centimeters are in an inch?
1 inch = 2.54 centimeters exactly. To convert inches to cm, multiply by 2.54. To convert cm to inches, divide by 2.54.
How do I convert Celsius to Fahrenheit?
°F = (°C × 9/5) + 32. For example, 20°C = 68°F. Quick reference: 0°C = 32°F, 100°C = 212°F, 37°C (body temp) = 98.6°F.
How many kilograms are in a pound?
1 pound = 0.453592 kg. 1 kg = 2.20462 lbs. Quick tip: divide pounds by 2.2 for approximate kg.
How many liters are in a gallon?
1 US gallon = 3.78541 liters. 1 UK gallon = 4.54609 liters. 1 liter = 0.264 US gallons.
How do I convert km to miles?
1 km = 0.621371 miles. 1 mile = 1.60934 km. Quick approximation: multiply km by 0.6 for miles.
How many feet are in a meter?
1 meter = 3.28084 feet. 1 foot = 0.3048 meters. 1 meter ≈ 3 feet 3.37 inches.
How many MB in a GB?
1 GB = 1,000 MB (decimal) or 1,024 MiB (binary). Storage uses decimal; OSes often use binary.
Converting between metric and imperial units is a skill that comes up constantly — whether you're cooking from a foreign recipe, planning an international trip, or reading a scientific paper. The good news is that most conversions rely on a handful of fixed multipliers that are easy to remember.
The metric system (SI) is built on powers of ten, making internal conversions trivial: there are exactly 1,000 meters in a kilometer, 1,000 grams in a kilogram, and 1,000 milliliters in a liter. Imperial units, by contrast, use irregular ratios — 12 inches to a foot, 3 feet to a yard, 5,280 feet to a mile — which is why calculators like this one save so much time.
For length, the anchor conversion is 1 inch = 2.54 cm. Everything else follows: multiply inches by 2.54 for centimeters, divide centimeters by 2.54 for inches. For weight, 1 pound = 0.4536 kg; a quick mental shortcut is to divide pounds by 2.2. For temperature, use °F = (°C × 1.8) + 32 — or remember that 0°C is freezing (32°F) and 100°C is boiling (212°F).
When precision matters — lab work, engineering, or medical dosages — always use a reliable converter and double-check units. A misplaced decimal between milligrams and grams can have serious consequences. For everyday use, memorizing two or three key multipliers is usually sufficient, and this tool handles the rest instantly.
Different areas of daily life each have their own set of conversions that come up again and again. Here are the most useful ones grouped by context.
Kitchen conversions are essential when scaling recipes or following instructions from another country. 1 cup (US) = 236.6 mL — so if a recipe calls for 2 cups of milk, that's about 473 mL. 1 ounce (oz) = 28.35 grams, meaning an 8 oz block of cheese weighs 227 grams. 1 tablespoon = 14.79 mL, and 3 teaspoons make 1 tablespoon, so 1 teaspoon ≈ 4.93 mL. European baking recipes almost always use grams for precision; American recipes use cups and spoons.
Travel conversions are the ones you need when crossing borders. 1 mile = 1.609 km — when a US speed limit sign says 60 mph, that's about 97 km/h. For temperature, a practical rule: below 10°C (50°F) pack a coat; above 30°C (86°F) expect heat. °C × 2 + 30 gives a rough Fahrenheit estimate that works well between 0°C and 30°C.
Fitness conversions matter at the gym and on race day. 1 lb = 0.4536 kg, so a 200 lb person weighs about 91 kg. For height, 1 inch = 2.54 cm; a 6-foot person (72 inches) is 182.9 cm tall. Running distances: a 5K is 3.11 miles, a 10K is 6.21 miles, and a marathon (26.2 miles) is 42.195 km. If you need to track your BMI, use a dedicated calculator that handles the lb/kg and in/cm conversions for you.
The coexistence of metric and imperial units is an accident of history. Before standardization, every region had its own local units — a "foot" literally meant the length of a human foot, and "pounds" varied from city to city. Trade and science demanded something better.
France solved the problem in 1795 by inventing the metric system, defining the meter as one ten-millionth of the distance from the equator to the North Pole. Its logical base-ten structure made it irresistible to scientists worldwide, and by the 20th century nearly every country had adopted it as the official standard.
The United States, Liberia, and Myanmar are the only countries that have not officially adopted the metric system for everyday use. The US came close in 1975 when Congress passed the Metric Conversion Act, but the conversion was made voluntary and largely stalled. As a result, Americans still buy gas by the gallon, measure height in feet and inches, and weigh themselves in pounds — while the rest of the world uses liters, centimeters, and kilograms. This mismatch is why unit converters remain among the most searched tools online. Need to manage time across your calculations? Our Time Calculator pairs well with unit conversions for travel and project planning.
How do I convert cups to milliliters?
1 US cup = 236.588 mL. To convert cups to mL, multiply by 236.6. For example, 2.5 cups = 591.5 mL. Note that a metric cup (used in Australia and Canada) = 250 mL, slightly larger than the US cup.
How many grams are in an ounce?
1 ounce (oz) = 28.3495 grams. To convert oz to grams, multiply by 28.35. To go the other way, divide grams by 28.35. This is a common kitchen conversion: an 8 oz portion of meat equals about 227 grams.
How do I convert inches to centimeters for height?
Multiply your height in inches by 2.54. For example, 5 feet 10 inches = 70 inches × 2.54 = 177.8 cm. A quick shortcut: 6 feet = 72 inches = 182.88 cm ≈ 183 cm. You can use the Length converter above — select Inch and Centimeter from the dropdowns.
What is the difference between a US gallon and a UK gallon?
A US gallon = 3.785 liters, while a UK (Imperial) gallon = 4.546 liters — about 20% larger. This matters most when comparing fuel economy: a car rated at 30 mpg in the US gets 36 mpg by UK measurement. Always check which gallon a recipe or spec sheet is using.