Need to switch between inches and centimeters, pounds and kilograms, or Fahrenheit and Celsius? Our free conversion calculator handles it all. Just pick your units, type in the number, and get your answer right away. No buttons, no waiting, just instant results for every conversion you need.
Here's the thing - there are a LOT of different units out there. Different countries use different systems. Different jobs use different measurements. And sometimes you just need to switch between them.
Our unit converter covers the most popular categories:
Length
inches, feet, yards, miles, mm, cm, meters, km
Weight
ounces, pounds, tons, grams, kilograms, metric tons
Volume
teaspoons, tablespoons, cups, pints, quarts, gallons, ml, liters
Temperature
Fahrenheit, Celsius, Kelvin
Speed
mph, km/h, knots, m/s
Area
sq inches, sq feet, acres, sq meters, hectares
And that's just the start. We keep adding more based on what people actually need.
Using our free unit converter is super simple. Here's how:
Pick the category you want to convert (like length or weight)
Choose the unit you're starting with (like inches)
Choose the unit you want to convert to (like centimeters)
Type in the number
Read your answer instantly
That's it. No buttons to click. No waiting. The result updates as you type.
Let's say you found a great cookie recipe online, but it's from the US and uses cups and Fahrenheit. You live in Europe and use grams and Celsius. First, convert 350°F to Celsius. Type "350" in the temperature converter. You get about 177°C. Perfect for baking. Then, convert 2 cups of flour to grams. But wait - cups measure volume, grams measure weight. Different ingredients have different densities. So 2 cups of flour is about 240 grams, but 2 cups of sugar is about 400 grams. Our calculator handles this by letting you pick the ingredient. So you'd select "flour" and get the right answer.
You might wonder why we can't all just use the same measurements. Good question.
The world mostly uses the metric system (meters, grams, liters). It's based on powers of 10, which makes math easy. Scientists love it. Most countries use it.
But the US, Myanmar, and Liberia still use the imperial system (feet, pounds, gallons). It's older and based on random things like the length of a king's foot. Not very scientific, but people are used to it. So when you need to switch between them, you need a metric conversion calculator.
Some conversions come up way more often than others. Here are the ones people search for the most:
This is probably the most common length conversion. One inch equals 2.54 centimeters exactly. So to convert cm to inches, you divide by 2.54. Or just use our calculator. Example: A 15.6-inch laptop screen is about 39.6 cm wide.
For weight, this is the big one. One kilogram equals about 2.205 pounds. So if you weigh 70 kg, that's about 154 lbs. Gym-goers use this all the time when plates are marked in kg but they think in lbs.
Temperature conversions are tricky because the scales don't line up at zero. Water freezes at 32°F but 0°C. It boils at 212°F but 100°C. The formula is: (°F - 32) × 5/9 = °C. So 68°F becomes (68-32) × 5/9 = 20°C. A nice room temperature.
Travelers need this one constantly. One mile equals about 1.609 kilometers. So a 5-mile run is about 8 km. In most of the world, road signs use kilometers. In the US and UK, they use miles. Knowing the conversion helps you figure out how far you're actually going.
Even smart people mess up conversions sometimes. Here are the most common errors:
Mixing up volume and weight
This is the #1 mistake. A cup is a measure of volume (how much space something takes up). A gram is a measure of weight (how heavy something is). A cup of feathers weighs way less than a cup of lead. So you can't just say "1 cup = X grams" without knowing what you're measuring. Our calculator handles this by letting you pick the ingredient.
Forgetting to convert both units
If you're converting speed, you need to convert both distance AND time. Miles per hour to kilometers per hour means changing miles to kilometers but keeping hours the same. But if you're converting meters per second to miles per hour, you're changing both distance and time. That's trickier.
Using the wrong conversion factor
There are 12 inches in a foot, but 3 feet in a yard. People sometimes mix these up. Or they use 2.54 for cm to inches but forget it's the other way around for inches to cm. Always double-check which direction you're converting.
Check your units: Make sure you selected the right starting and ending units. It's easy to accidentally convert kg to oz instead of kg to lbs.
Use enough decimal places: For precise work like engineering or science, use more decimal places. For cooking, rounding to the nearest whole number is usually fine.
Know when to use exact vs approximate: Some conversions are exact (1 inch = 2.54 cm exactly). Others are approximate (1 mile ≈ 1.609 km). Our calculator uses the most accurate values.
Test with a known value: If you're not sure the calculator is working right, test it with something you know. Like 0°C should equal 32°F. If it doesn't, something's wrong.
Pretty much everyone at some point. But here are the people who use them most:
Science and math classes love conversions. Physics problems, chemistry experiments, even geography homework. Students use conversion calculators to check their work or speed things up.
Recipes from different countries use different units. A British recipe might use grams while an American one uses cups. Conversion calculators save you from ruining a dish.
When you're in a different country, everything is in different units. Road signs in km, weather in °C, food in grams. A quick conversion helps you understand what's going on.
Building materials come in different sizes depending on where they're made. A 2x4 in the US is different from a 50x100 mm in Europe. Converting helps you buy the right stuff.
Gym equipment is often marked in kg in some countries and lbs in others. Converting helps you track your lifts accurately.
There are plenty of conversion tools out there. Here's why ours is different:
It's free
No sign-ups, no ads, no limits. Just use it.
Works on any device
Phone, tablet, laptop, desktop. The layout adjusts automatically.
It's fast
Results update as you type. No button clicking.
Covers a lot
Length, weight, volume, temperature, speed, area, and more.
Handles tricky conversions
Like volume to weight for specific ingredients.
Did you know the meter was originally defined as one ten-millionth of the distance from the North Pole to the Equator? That was in 1793. Today, it's defined by the speed of light. Science is wild.
And the pound? It comes from the Roman "libra," which is why its symbol is "lb." So next time you see "lbs" on a weight, you're using ancient Roman units.
Learn the common conversion factors: Knowing that 1 inch = 2.54 cm or 1 kg = 2.205 lbs helps you estimate quickly without a calculator.
Use the calculator for checking your work: Do the math yourself first, then use the calculator to verify. This helps you learn.
Bookmark the calculator: If you convert units often, save the page. It's faster than searching every time.
Understand significant figures: For science work, know how many decimal places are meaningful. Our calculator gives you plenty, but you might need to round.
When you need to understand the concept
If you're learning about unit conversions in school, do the math yourself first. The calculator is for checking, not skipping.
When precision matters a lot
For scientific research or engineering, use the exact conversion factors from reliable sources. Our calculator is accurate, but always double-check critical work.
When the conversion doesn't make sense
You can't convert temperature to length. You can't convert weight to time. Make sure you're converting between compatible units.
Just select "Length" as the category, choose "Centimeters" as the starting unit and "Inches" as the target unit. Then type in the number of centimeters. The result appears instantly. For example, 10 cm equals about 3.94 inches.
Different calculators might use slightly different conversion factors. For example, some round 1 kg to 2.2 lbs while others use 2.20462. Our calculator uses the most accurate values. Also, check that you selected the right units — it's easy to accidentally convert in the wrong direction.
Yes, but you need to know what ingredient you're measuring. A cup of flour weighs about 120 grams, but a cup of sugar weighs about 200 grams. Our calculator lets you select the ingredient to get the right conversion. Without that, you'll get wrong results.
Metric units (meters, grams, liters) are based on powers of 10, making them easy to work with. Imperial units (feet, pounds, gallons) are older and based on arbitrary things like body parts. Most of the world uses metric, but the US, Myanmar, and Liberia still use imperial.
A quick trick: subtract 32, then divide by 2, then add 10% of that result. For example, 68°F: 68-32=36, 36/2=18, 18+1.8≈20°C. For a more accurate result, use our calculator. The exact formula is (°F - 32) × 5/9.
The most common mistake is mixing up volume and weight. A cup measures volume (space), while a gram measures weight (mass). You can't directly convert between them without knowing the density of the material. Another common error is using the wrong conversion factor or converting in the wrong direction.
One kilogram equals about 2.205 pounds. So if a barbell plate is 20 kg, it's about 44 lbs. Use our weight converter — just enter the kg and it instantly shows the lbs.
We cover the most common categories: length, weight, volume, temperature, speed, and area. But you can't convert between incompatible units like temperature to length. If a specific conversion isn't available, let us know and we might add it.
Very accurate. We use the standard, internationally recognized conversion factors. For most everyday needs, the accuracy is more than sufficient. For critical scientific work, we provide enough decimal places but recommend verifying with authoritative sources.
Our calculator is web-based and requires an internet connection. But the page loads quickly, so you can use it wherever you have signal.
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