Free tool

Unit converter

Convert between length, weight, volume, speed, area, data, temperature, time, and energy units instantly.

What is Unit Converter?

A unit converter is a tool that translates measurements from one unit system to another — for example, converting kilometers to miles, Celsius to Fahrenheit, or kilojoules to calories. This free online unit converter covers nine major categories: length, weight, volume, speed, area, data storage, temperature, time, and energy, with over 70 individual units. Temperature conversions use proper formulas (not simple multiplication), and all conversions happen in real time as you type. The tool shows the exact conversion formula so you understand the math behind every result. Whether you are a developer calculating file sizes, a student solving physics problems, an engineer converting metric to imperial, or a cook scaling recipes, this converter handles it all in one place.

How to Use Unit Converter

1
Select a category
Choose from Length, Weight, Volume, Speed, Area, Data, Temperature, Time, or Energy using the category tabs. Each category loads its own set of units relevant to that measurement type.
2
Pick your units and enter a value
Select the source unit in the From dropdown and the target unit in the To dropdown. Type a number in the value field. Use the swap button to quickly reverse the conversion direction.
3
Read and copy the result
The converted value appears instantly below the input along with the conversion formula. Click the Copy button to copy the full conversion result to your clipboard.

Features

Nine conversion categories: length, weight, volume, speed, area, data, temperature, time, energy
Over 70 units with precise conversion factors
Temperature: Celsius, Fahrenheit, Kelvin with correct formulas
Time: milliseconds to years including months and weeks
Energy: joules, calories, BTU, watt-hours, electron-volts
Real-time conversion that updates instantly as you type
One-click swap button to reverse from and to units
Displays the conversion formula for every conversion

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Frequently Asked Questions

How does temperature conversion work?+

Unlike other units, temperature uses formulas instead of simple multiplication. Celsius to Fahrenheit: F = C x 9/5 + 32. Celsius to Kelvin: K = C + 273.15. The tool applies the correct formula for each direction automatically.

Are the data storage conversions binary or decimal?+

This tool uses binary (base-1024) conversions for data storage units, which is the standard used by operating systems. So 1 KB = 1,024 bytes, 1 MB = 1,024 KB, and so on.

What is the difference between calories and kilocalories?+

A kilocalorie (kcal) equals 1,000 calories. The "calories" on food labels are actually kilocalories. In this tool, cal = small calorie (4.184 J) and kcal = food calorie (4,184 J).

How precise are the conversions?+

The tool uses high-precision conversion factors and displays results with up to 12 significant digits. For everyday use this provides more than enough accuracy.

What is a BTU?+

A British Thermal Unit (BTU) is the amount of heat needed to raise 1 pound of water by 1 degree Fahrenheit. It equals approximately 1,055 joules. BTU is commonly used in HVAC, heating, and energy industries.

Can I convert between categories?+

No. Each category represents a different physical quantity, so you cannot convert meters to kilograms. The swap button only works within the same category.

What is Unit Converter?

How to Use Unit Converter

Select a category

Choose from Length, Weight, Volume, Speed, Area, Data, Temperature, Time, or Energy using the category tabs. Each category loads its own set of units relevant to that measurement type.

Pick your units and enter a value

Select the source unit in the From dropdown and the target unit in the To dropdown. Type a number in the value field. Use the swap button to quickly reverse the conversion direction.

Read and copy the result

The converted value appears instantly below the input along with the conversion formula. Click the Copy button to copy the full conversion result to your clipboard.

Features

Nine conversion categories: length, weight, volume, speed, area, data, temperature, time, energy

Over 70 units with precise conversion factors

Temperature: Celsius, Fahrenheit, Kelvin with correct formulas

Time: milliseconds to years including months and weeks

Energy: joules, calories, BTU, watt-hours, electron-volts

Real-time conversion that updates instantly as you type

One-click swap button to reverse from and to units

Displays the conversion formula for every conversion

Frequently Asked Questions

How does temperature conversion work?+

Are the data storage conversions binary or decimal?+

This tool uses binary (base-1024) conversions for data storage units, which is the standard used by operating systems. So 1 KB = 1,024 bytes, 1 MB = 1,024 KB, and so on.

What is the difference between calories and kilocalories?+

A kilocalorie (kcal) equals 1,000 calories. The "calories" on food labels are actually kilocalories. In this tool, cal = small calorie (4.184 J) and kcal = food calorie (4,184 J).

How precise are the conversions?+

The tool uses high-precision conversion factors and displays results with up to 12 significant digits. For everyday use this provides more than enough accuracy.

What is a BTU?+

Can I convert between categories?+

No. Each category represents a different physical quantity, so you cannot convert meters to kilograms. The swap button only works within the same category.