How to use the Unit Converter
- Pick a category — length, weight, temperature, area, volume, speed, time or data storage.
- Enter a value and choose the unit you are converting from and to. The result updates as you type.
- Use the quick-reference table below the result to see common values at a glance, or press Swap units to convert the other way.
What this tool does
It converts between metric and imperial (US customary) units in eight categories that come up in everyday life: recipes, travel, DIY, fitness, shopping, school science, and working out how much storage a file really needs. All conversion factors are built into the page, so it works instantly and even offline once loaded — there is no external service involved.
How conversions work
For most categories, every unit is defined by an exact factor relative to one base unit (the metre for length, the kilogram for mass, the litre for volume, and so on). Converting from unit A to unit B means multiplying by A's factor and dividing by B's factor. Most of these factors are exact by international definition — for example, one inch is exactly 2.54 cm and one pound is exactly 0.45359237 kg.
Temperature is different
Temperature scales have different zero points, so they need formulas rather than a single factor:
°F = °C × 9/5 + 32 · °C = (°F − 32) × 5/9 · K = °C + 273.15
This is why doubling a temperature in Celsius does not double it in Fahrenheit: 10 °C is 50 °F, but 20 °C is 68 °F.
Data storage: KB vs KiB
Storage units come in two families. Decimal units (KB, MB, GB, TB) use powers of 1,000 and are what drive and phone manufacturers use. Binary units (KiB, MiB, GiB, TiB) use powers of 1,024 and are what many operating systems actually report — sometimes still labelled "GB". That is why a "1 TB" drive shows up as roughly 931 GB on some computers: 1,000,000,000,000 bytes ÷ 1,073,741,824 ≈ 931 GiB.
US vs imperial volumes
A US gallon (3.785 L) is smaller than an imperial (UK) gallon (4.546 L), and the same is true for pints and fluid ounces. The converter labels both clearly — check which one your recipe or fuel figure uses.
Examples
| Conversion | Result | Everyday context |
|---|---|---|
| 5 km → miles | 3.107 mi | A "5K" run |
| 70 kg → pounds | 154.32 lb | Body weight |
| 180 °C → °F | 356 °F | Oven temperature |
| 100 km/h → mph | 62.14 mph | Speed limits abroad |
| 1 US cup → mL | 236.59 mL | Recipes |
| 1 GB → MiB | 953.67 MiB | File sizes |
Tips
- Mind the rounding. Results are shown to a sensible number of significant digits. For engineering or scientific work, check the precision you need.
- Months and years are averages. In the time category, a month is the average Gregorian month (30.44 days) and a year is 365.2425 days. For exact calendar spans, use the Date Difference Calculator.
- Image sizes: the data category tells you how big a file is; to actually make a photo smaller, use the Image Compressor.
- Comparing changes? Convert both values to the same unit, then use the Percentage Calculator to find the difference.
Frequently asked questions
How accurate are the conversions?
The conversion factors are exact international definitions wherever one exists (such as 1 inch = 2.54 cm). Results are rounded for display to avoid meaningless digits.
Why does my 1 TB drive show less space?
Manufacturers count 1 TB as 1,000,000,000,000 bytes, while many operating systems report space in binary units (1 TiB = 1,099,511,627,776 bytes). The same drive therefore shows as about 931 "GB".
What is the difference between weight and mass?
Strictly, mass is the amount of matter (kilograms) and weight is a force. In everyday use — and on bathroom scales — "weight" means mass, which is what this converter measures.
Does it work offline?
Yes. Once the page has loaded, all conversions happen in your browser without any further network requests.
Last updated . Spotted a mistake? Let us know and we will correct it.