Unit Converter

Convert metric and Imperial units side by side

This converter keeps a metric value and an Imperial value visible at the same time. Type into either side, choose the unit you need, and the other side updates instantly. It covers area, length, temperature, volume, and weight or mass.

Each section keeps one underlying measurement and derives both displayed values from it. That means you can change a unit dropdown at any time without gradually losing accuracy through repeated rounded conversions.

Length and area conversions

Metric length units scale by powers of ten: 10 millimeters make a centimeter, 100 centimeters make a meter, and 1,000 meters make a kilometer. Imperial length uses inches, feet, yards, and miles. One inch is exactly 25.4 millimeters, and one foot is exactly 0.3048 meters.

Area measures a two-dimensional surface, so the conversion factor is squared. One square meter is about 10.764 square feet; one hectare is 10,000 square meters; and one acre is about 4,046.86 square meters. Use the Area section for flooring, land, paint coverage, and plan dimensions.

Construction-friendly eighths of an inch

Many construction and fabrication drawings use eighth-inch increments. Select 1/8″ in the Length section to express a measurement as a count of eighths rather than a decimal number of inches. One eighth of an inch is exactly 3.175 millimeters.

Temperature: Celsius, Fahrenheit, Kelvin, and Newton

Temperature needs a formula rather than a fixed multiplier because Celsius and Fahrenheit start at different zero points. The familiar conversion is:

°F = (°C × 9 ÷ 5) + 32

Kelvin uses the same size degree as Celsius but starts at absolute zero: K = °C + 273.15. The Newton scale is less common but useful in historical and scientific contexts: °N = °C × 0.33. Enter any one of the four temperatures and the other three update together.

Volume: choose US or UK measures carefully

Metric volume is usually expressed in milliliters and liters. One liter is 1,000 milliliters and is equal to one cubic decimeter. For larger quantities, one cubic meter is 1,000 liters.

US customary and UK Imperial volume measures are different. A US gallon is 3.785411784 liters, while a UK gallon is 4.54609 liters. Pints, quarts, fluid ounces, and gallons therefore need their country label; choose the explicitly marked US or UK option rather than assuming the names are interchangeable.

Weight and mass

The metric system uses grams and kilograms. One kilogram is 1,000 grams. For everyday Imperial or US customary weight, one pound is exactly 453.59237 grams and one ounce is exactly 28.349523125 grams. This converter also includes US short tons and Imperial long tons, which are different sizes.

For ordinary use, “weight” and “mass” are used interchangeably. Strictly speaking, mass measures the amount of matter while weight is the force gravity applies to it. The listed everyday units convert by the conventional mass equivalences used in trade, cooking, construction, and transport.

Frequently asked questions

How do I convert metric units to Imperial units?

Enter a value on either side of the relevant section and choose its unit. The paired value updates immediately in the unit selected on the other side. You can change either unit without losing the underlying measurement.

What is the difference between Imperial and US customary units?

They share many names but not always the same sizes. A UK gallon is larger than a US gallon, and UK fluid ounces, pints, and quarts also differ from US measures. This converter labels US and UK volume units separately so you can choose the right one.

Why is 1/8 inch included as a length unit?

Eighths of an inch are widely used in construction and fabrication. Select 1/8" to work in counts of one-eighth-inch increments instead of converting through a decimal-inch value.

How do Celsius, Fahrenheit, Kelvin, and Newton convert?

Temperature scales do not convert by a simple multiplier because Celsius and Fahrenheit use different zero points. The calculator keeps one Kelvin value internally and derives Celsius, Fahrenheit, Kelvin, and Newton from it, so changing any one updates the other three accurately.

Are my conversion values saved?

The conversions run in your browser. Values and selected units can appear in the page address when you share a calculation, but they are not uploaded or stored by this tool.