The formula
How it works
Convert between units of length, weight, volume and temperature. Pick a category, choose the units you are converting from and to, and enter a value.
FAQ
How does temperature conversion differ?
Temperatures do not scale from zero like other units, because each scale has a different zero point. So instead of multiplying by a factor, the calculator converts through Celsius using the proper formulas, such as °F = °C × 9/5 + 32.
Which gallon does the volume use?
The US gallon (3.785 litres). The UK imperial gallon is larger, about 4.546 litres, so be sure which one a recipe or spec means before converting.
How precise are the results?
The calculator keeps up to six significant digits, which is far more precision than most real-world uses need. For everyday purposes you can safely round the result to one or two decimal places.
Can I convert in the opposite direction?
Yes, just swap the From and To units — the calculator recalculates instantly using the same value. There is no need to re-enter the number.
Are the conversion factors exact?
Most, like miles to kilometres and pounds to kilograms, are defined exactly by international standards, so the results are as accurate as the arithmetic itself. Only the underlying measurement you enter can introduce error, not the conversion.
Why are there so many volume units?
Volume is measured differently depending on context — cups and fluid ounces are common in cooking, litres in science and most of the world, and gallons for fuel and large liquids in the US. Having them all in one place avoids hunting for separate converters.
Why do metric and imperial units still coexist?
Most countries adopted the metric system for its simple base-10 scaling, but the US and a few others still use imperial units for everyday measurement, and imperial terms persist in cooking and some industries worldwide. That mix is exactly why a quick converter is so useful.
About the conversion calculator
This calculator converts a value from one unit to another across the four most common measurement types: length, weight, volume and temperature. Unit conversion is a constant need in cooking, travel, science, DIY and trade, where the same quantity can be measured in metric or imperial units. Rather than remembering dozens of conversion factors, you pick the units and the calculator does the arithmetic exactly.
How to use it
Choose a category — length, weight, volume or temperature — then select the unit you are converting from and the unit you want, and enter the value. The result appears instantly. For example, 1 mile converts to 1.609 kilometres, 1 kilogram to about 2.205 pounds, and 100°C to 212°F. Switch the from and to units at any time to convert in the other direction.
The formula
For length, weight and volume, each unit has a factor relative to a base unit, and the conversion is . Temperature is handled differently because the scales have different zero points: the calculator converts the input to Celsius, then out to the target scale using formulas like and .
Where it is used
Unit conversion comes up everywhere metric and imperial systems meet. Cooks convert recipe amounts, travellers convert distances and temperatures, engineers and scientists convert measurements between systems, and shoppers compare products sold in different units. A reliable converter removes the risk of the small slips that unit mix-ups famously cause, from kitchen mishaps to costly engineering errors.