Conversion Calculator
Convert between units in twelve categories — length, area, volume, mass, temperature, speed, time, digital storage, energy, pressure, power, and angle. Pick a category, choose your from/to units, and enter a value to see the exact conversion factor used.
One multiplication, twelve categories
Almost every unit conversion is the same operation: multiply by a fixed factor to reach a common base unit, then divide by the target unit’s factor. A mile converts to kilometers the same mechanical way a kilobyte converts to bytes — only the numbers change. Temperature is the lone exception, because Celsius, Fahrenheit, and Kelvin don’t share a common zero point, so it needs an offset in addition to a scale factor. Everything on this page uses internationally standardized, exact definitions wherever one exists — the foot, the pound, and the international mile all have fixed, agreed values with no rounding involved.
How it’s calculated
For all categories except temperature: converted value = input value × (from-unit factor ÷ to-unit factor), where each unit’s factor expresses it in a shared base unit for that category (meters for length, liters for volume, bytes for digital storage, and so on). Temperature converts via Celsius as an intermediate step: convert the input to Celsius first, then from Celsius to the target scale, using °F = °C × 9⁄5 + 32 and K = °C + 273.15.
Results update as you type. Physical unit definitions (meters, feet, pounds, and similar) are exact by international agreement; a few calendar units (month, year) use a standard average value, noted where relevant.
Common conversions
| Convert | Factor | Example |
|---|---|---|
| 1 mile | 1.609344 km | 100 mi = 160.9344 km |
| 1 US gallon | 3.785411784 L | 5 gal = 18.927 L |
| 1 pound | 0.45359237 kg | 150 lb = 68.039 kg |
| 1 acre | 0.404686 hectares | 10 acres = 4.047 hectares |
| 1 horsepower | 745.699872 W | 2 hp = 1,491.4 W |
| 1 psi | 0.068046 atm | 14.7 psi = 1.0000 atm |
| 0°C | 32°F, 273.15 K | 98.6°F = 37.00°C |
Worked example
100 miles converts to 160.9344 kilometers exactly — the international mile is defined as precisely 1.609344 km. 150 pounds is 68.0389 kilograms. A body temperature of 98.6°F converts to exactly 37.00°C. And 1 gigabyte equals 1,000 megabytes using the standard decimal (SI) definition this calculator uses throughout.
Common mistakes
- Confusing decimal storage units (1 GB = 1,000 MB) with binary ones (1 GiB = 1,024 MiB) — operating systems and manufacturers don’t always use the same convention.
- Treating a US gallon and an imperial (UK) gallon as the same size — they differ by about 20%.
- Applying a simple multiplication to temperature instead of using the offset formula, which produces a wildly wrong answer.
Where it is used
- Cooking, home improvement, and travel conversions between metric and US customary units.
- Science and engineering coursework that mixes unit systems.
- Checking a spec sheet, recipe, or shipment listed in unfamiliar units.
Frequently asked questions
Why is temperature conversion different from the other categories?
Every other category converts by multiplying by a fixed factor, because their scales all start at zero together (0 meters is 0 feet). Temperature scales don't share a zero point — 0°C is 32°F, not 0°F — so converting requires an offset (subtract or add 32, or add 273.15 for Kelvin) in addition to scaling, which is why it needs its own formula instead of a simple multiplier.
What's the exact factor between miles and kilometers?
1 mile = 1.609344 kilometers exactly, by international agreement (the 1959 international yard and pound agreement, which also fixed the foot at exactly 0.3048 meters). Every length conversion in this calculator ultimately derives from that same fixed relationship.
Is a US gallon the same as an imperial gallon?
No — a US gallon (3.785411784 liters) is smaller than an imperial gallon (about 4.546 liters), used in the UK and some Commonwealth countries. This calculator uses US customary units (gallons, quarts, pints, cups, fluid ounces) throughout, which is the default in the United States.
What's the difference between a kilobyte (KB) and a kibibyte (KiB)?
A kilobyte is 1,000 bytes (decimal, the SI-standard prefix), while a kibibyte is 1,024 bytes (binary, based on powers of 2). Storage manufacturers typically advertise decimal units, while operating systems often report binary ones — which is the most common reason a drive shows less capacity than its label after formatting.
How precise are these conversion factors?
Most are exact by international definition (meters, feet, pounds, and similar physical units all have fixed, agreed conversion factors with no rounding). A few calendar-based units like month and year use an average value (there is no single exact answer for how many seconds are in "a month"), which this calculator notes wherever it applies.