Free Unit Converter — Length, Weight, Temperature, Volume & More

Whether you are converting kilograms to pounds for a gym program, Celsius to Fahrenheit for a weather check, or cups to milliliters for a recipe, unit conversions come up constantly. And getting them wrong has real consequences — from ruined recipes to medication dosing errors.

Our free unit converter handles every common conversion instantly. Length, weight, temperature, volume, speed, area, and more — just pick your units, enter a number, and get the result. No signup, no ads blocking the answer.

The Conversions People Search for Most

Based on search volume, these are the unit conversions people look up most frequently:

Conversion	Formula	Quick Reference
Kg to Lbs	Multiply by 2.2046	70 kg = 154.3 lbs
Miles to Km	Multiply by 1.6093	10 miles = 16.1 km
Celsius to Fahrenheit	(C x 9/5) + 32	25°C = 77°F
Inches to Cm	Multiply by 2.54	12 inches = 30.5 cm
Gallons to Liters	Multiply by 3.7854	5 gallons = 18.9 liters
Feet to Meters	Multiply by 0.3048	6 feet = 1.83 meters

The pattern is clear: most searches are metric-to-imperial or imperial-to-metric. The US uses imperial; nearly every other country uses metric. If you work, travel, or cook across systems, you need a converter you can trust.

Metric vs. Imperial — A Quick Reference

The metric system is built on powers of 10. Kilo means 1,000, centi means 1/100, milli means 1/1,000. Once you know the prefixes, every metric conversion is just moving a decimal point. One kilometer = 1,000 meters. One kilogram = 1,000 grams. One liter = 1,000 milliliters.

Imperial units have no such pattern. There are 12 inches in a foot, 3 feet in a yard, 5,280 feet in a mile. There are 16 ounces in a pound, 2,000 pounds in a ton. There are 8 fluid ounces in a cup, 2 cups in a pint, 2 pints in a quart, 4 quarts in a gallon. The inconsistency is why conversion tools exist.

For mental math shortcuts: 1 inch is roughly 2.5 cm (exact: 2.54). 1 kg is roughly 2.2 lbs. 1 mile is roughly 1.6 km. 1 liter is roughly a quarter gallon (exact: 0.264 gallons). These approximations are close enough for everyday estimates.

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Cooking Conversions That Trip Everyone Up

Cooking is where unit confusion causes the most frustration, especially with international recipes. Here are the conversions that catch people off guard:

• Cups to grams: A cup of flour weighs about 125 grams. A cup of sugar weighs about 200 grams. A cup of butter weighs about 227 grams. The weight varies by ingredient — there is no single cups-to-grams conversion.
• Tablespoons to milliliters: 1 US tablespoon = 14.79 ml. 1 Australian tablespoon = 20 ml. This matters when following Australian recipes.
• Oven temperatures: European recipes use Celsius. A 350°F oven = 177°C (rounded to 180°C). A 400°F oven = 204°C (rounded to 200°C). UK recipes sometimes use gas marks — Gas Mark 4 = 350°F = 180°C.
• Fluid ounces vs. weight ounces: A recipe calling for "8 oz of chocolate" means weight. "8 oz of milk" means fluid ounces (volume). Context matters, and getting it wrong ruins the result.

Travel Conversions You Actually Need

International travel puts you face-to-face with unfamiliar units daily. Here are the ones that matter most:

• Temperature: If a European weather forecast says 35°C, that is 95°F — pack accordingly. Below 0°C means freezing. A comfortable room is 20-22°C (68-72°F).
• Distance: Speed limit signs in most countries are in km/h. A 100 km/h limit equals 62 mph. A 130 km/h highway (common in Europe) equals 81 mph.
• Fuel: Most countries sell gas by the liter. If you see 1.80 per liter, multiply by 3.785 to get the per-gallon equivalent: $6.81 per gallon. Fuel economy is measured in liters per 100 km (lower is better) rather than miles per gallon (higher is better).
• Weight and height: Your doctor in the US says you are 5'10" and 170 lbs. Overseas, that is 178 cm and 77 kg. Knowing your measurements in both systems saves time at pharmacies, clothing stores, and medical visits abroad.

Frequently Asked Questions

How do I convert Celsius to Fahrenheit?

Multiply the Celsius temperature by 9/5, then add 32. The formula is: °F = (°C x 9/5) + 32. For example, 25°C = (25 x 1.8) + 32 = 77°F. For a quick mental estimate, double the Celsius number and add 30 — not exact, but close enough for everyday use.

Why does the US still use imperial units?

The US customary system is deeply embedded in infrastructure, manufacturing, real estate, and daily life. Converting road signs, construction standards, product packaging, and consumer expectations would cost billions. Congress authorized metric adoption in 1975 but made it voluntary, so adoption stalled. Only three countries — the US, Myanmar, and Liberia — have not officially adopted the metric system as their primary measurement standard.

What is the difference between fluid ounces and ounces?

Ounces (oz) measure weight. Fluid ounces (fl oz) measure volume. They are not interchangeable. One fluid ounce of water happens to weigh approximately one ounce, but this is a coincidence specific to water. One fluid ounce of honey weighs about 1.5 ounces because honey is denser than water. Always check whether a recipe or label means weight ounces or fluid ounces.