Introduction
This Metric Conversion Calculator changes one unit into another in seconds. Type a number in any box, and every other box fills in right away. You can convert weight, length, area, volume, temperature, pressure, and energy.
It works both ways. Go from metric to imperial, like kilograms to pounds or meters to feet. Or go the other way, like inches to centimeters or gallons to liters. Popular picks, like °C to °F, are one click away.
You also see the math. The step-by-step solution shows how the answer was found, so you can check your work or learn the method. A bar chart shows your value in every unit at once. You can set how many decimal places you want, search for a unit by name or symbol, and copy any answer with one tap.
How to use our Metric Conversion Calculator
Type a number into any unit box, and the calculator fills in every other unit in that group right away. You also get a step-by-step solution and a bar chart of all the equal values.
Search for a unit: Type a unit name or symbol, like "kg", "miles" or "PSI". The matching unit boxes light up and scroll into view.
Popular Conversions: Click a button like "km → miles" to jump to that pair. It sets the value to 1 so you can start typing.
Category tabs: Pick Weight, Length, Area, Volume, Temperature, Pressure or Energy to move to that section.
Unit value box: Enter your number in the unit you have, such as meters, pounds or °C. All the other units in that section update at once.
Decimal Places: Choose Auto, 2, 4, 6 or 8 to set how many decimals your answers show. If you need to round to a set number of significant digits instead, try the Sig Fig Calculator.
Show More Units: Click this to open extra units, like nautical miles, acres, barrels or BTU.
Copy button: Click the clipboard icon next to any answer to copy that number.
Clear All: Click this to empty every box in that one category.
Convert to: In the Step-by-Step Solution, pick the unit you want the math worked out for.
Calculate and Reset: Click Calculate to refresh all results. Click Reset to start over with the sample values.
What Is Metric Conversion?
Metric conversion means changing a measurement from one unit to another. For example, you can turn kilometers into miles, kilograms into pounds, or Celsius into Fahrenheit. The number changes, but the real size stays the same. One meter and 3.28 feet are the same length, just written in different units.
Metric vs. Imperial Units
Most countries use the metric system. It is built on units like meters, grams, and liters, and every step goes up or down by 10. That makes math easy: 1 kilometer is 1,000 meters, and 1 centimeter is one hundredth of a meter.
The United States mostly uses the imperial (US customary) system, with inches, feet, miles, pounds, ounces, and gallons. These units do not follow a simple pattern. There are 12 inches in a foot, 3 feet in a yard, and 5,280 feet in a mile. That is why people often need a conversion tool, or a helper like the Feet and Inches Calculator when you are working in mixed units.
How Unit Conversion Works
Most conversions use one simple step: multiply by a number called a conversion factor. To change feet to meters, multiply by 0.3048. To go the other way, divide by 0.3048. Every unit in a group (like length) is linked to one base unit, so any unit can be changed into any other. The same idea powers focused tools such as the Mm to Inches Calculator, the Grams to Ounces Calculator, and the Pounds to Kilograms Calculator.
Temperature is different. Celsius, Fahrenheit, and Kelvin do not start at the same zero point, so you must add or subtract as well as multiply. To change Celsius to Fahrenheit, multiply by 9/5 and then add 32. For the reverse trip, use the Fahrenheit to Celsius Calculator or the general Temperature Calculator.
Common Conversions to Know
- 1 inch = 2.54 centimeters (see the Cm to Inches Calculator)
- 1 foot = 0.3048 meters (see the Feet to Meters Calculator)
- 1 mile = 1.609 kilometers
- 1 kilogram = 2.205 pounds
- 1 ounce = 28.35 grams (see the Ounces to Grams Calculator)
- 1 liter = 0.264 US gallons (see the Volume Conversion Calculator)
- 1 acre = 4,047 square meters (see the Sq Ft to Acres Calculator and the Area Converter Calculator)
- 0 °C = 32 °F = 273.15 K
- 1 MPa = 145.04 psi
Why It Matters
Cooking, travel, school work, shipping, building, and engineering all use different units. A recipe may list grams while your scale shows ounces. A road sign may show kilometers while your car shows miles. Getting the units wrong can waste money or cause serious mistakes, so careful conversion keeps your numbers correct.
Unit changes show up in a lot of everyday math too. Builders move between square footage, cubic yards, and linear feet on the same job. Shippers compare weight and size with the Volumetric Weight Calculator or the CBM Calculator. Engineers convert material sizes into mass using the Metal Weight Calculator or the Steel Weight Calculator, and often need density figures in matching units.
Tips for Accurate Results
Always check which unit you started with. Watch out for units that share a name but not a size, like US gallons and UK gallons, or short tons and long tons. Round only at the end of your work, not in the middle, so small errors do not add up. If you want to see how far off a rounded answer is, the Percent Error Calculator and the Rounding Calculator can help. For very large or very small numbers, the Scientific Notation Calculator keeps things readable.