How Unit Conversion Works
A unit conversion changes the unit used to express a quantity without changing the quantity itself. For most categories, this tool converts the source value to a shared base unit and then converts that base value to the selected target unit. For example, the international inch is defined as exactly 0.0254 meter, so the same relationship can convert inches to meters, centimeters, feet, or miles.
Temperature scales also require an offset. Celsius and Kelvin use the same interval size but different zero points, while Fahrenheit uses a different interval and zero point. The converter applies the complete equations and prevents values below absolute zero. It does not convert unlike quantities: volume cannot become mass without a material density, and energy cannot become power without a time interval.
Supported Conversion Categories
Length & Distance
Convert between 11 supported units in this category.
Weight & Mass
Convert between 7 supported units in this category.
Temperature
Convert between 3 supported units in this category.
Area
Convert between 8 supported units in this category.
Speed
Convert between 5 supported units in this category.
Volume
Convert between 12 supported units in this category.
Time
Convert between 6 supported units in this category.
Digital Storage
Convert between 13 supported units in this category.
Pressure
Convert between 7 supported units in this category.
Energy
Convert between 8 supported units in this category.
Power
Convert between 5 supported units in this category.
Where Unit Conversions Are Used
Engineering Calculations
Convert between SI and imperial units for mechanical, civil, and electrical engineering projects.
Construction Projects
Switch between feet, meters, and square footage for architectural plans and material estimates.
Scientific Research
Accurately convert SI units across experiments, lab reports, and published datasets.
Academic Studies
Solve unit conversion problems for physics, chemistry, and mathematics coursework.
Fitness & Nutrition
Convert kilograms to pounds, kilometers to miles, and Celsius to Fahrenheit for workouts and diets.
International Travel
Understand local temperatures, distances, and speed limits when traveling between metric and imperial countries.
Shipping & Logistics
Convert package weights and dimensions between metric and imperial systems for international shipping.
Manufacturing
Convert measurement tolerances and specifications between international unit standards on production lines.
SI, U.S. Customary, Imperial, and Binary Units
The International System of Units (SI) is the modern metric system. Decimal prefixes such as milli, kilo, and mega represent powers of ten. U.S. customary and British imperial units share names such as gallon and pint but are not interchangeable: one U.S. liquid gallon and one imperial gallon have different volumes. This converter labels those choices separately.
Digital storage has a similar naming distinction. Decimal units use powers of 1,000, so 1 MB equals 1,000,000 bytes. IEC binary units use powers of 1,024, so 1 MiB equals 1,048,576 bytes. A byte contains eight bits; bits are commonly used for data-transfer rates, while bytes are commonly used for file and storage sizes.
| Relationship | Value | Important distinction |
|---|---|---|
| International inch | 1 in = 0.0254 m exactly | The international foot is exactly 0.3048 m. |
| Nautical mile | 1 nmi = 1852 m exactly | A nautical mile is not a statute mile. |
| US liquid gallon | 1 US gal = 3.785411784 L | Do not substitute an imperial gallon. |
| Imperial gallon | 1 imp gal = 4.54609 L | Approximately 20% larger than a US gallon. |
| Decimal megabyte | 1 MB = 1,000,000 B | Uses the SI prefix mega. |
| Binary mebibyte | 1 MiB = 1,048,576 B | Uses the IEC binary prefix mebi. |
Unit Conversion Tips & Best Practices
Check High-Stakes Measurements
This tool is suitable for general calculation and comparison, but it cannot verify the original measurement, instrument calibration, tolerances, local regulation, or industry-specific convention. Confirm safety-critical, medical, laboratory, aviation, structural, manufacturing, and legal-metrology conversions with the governing standard or a qualified professional.
Measurement References
These official references explain SI usage, published conversion tables, and decimal versus binary prefixes. External links open in a new tab.
Continue Your Calculation Workflow
Use the Percentage Calculator for changes, proportions, and reverse percentages. For calendar intervals rather than fixed seconds, use the Duration Calculator. To turn appliance power and usage time into an estimated cost, continue with the Electricity Bill Calculator.