Unit Converter
Converts a value between length, mass, temperature, volume, area, speed and digital storage.
Category
Source unit
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When to use each category
| Category | Example | Where it's used |
|---|---|---|
| Length | 5 km | Distances, dimensions, everyday measurements |
| Mass & Weight | 70 kg | Body weight, cargo weight, cooking recipes |
| Temperature | 36.5 °C | Weather, cooking, health — Fahrenheit is common in US content |
| Volume | 1 gallon | Fuel, liquids, cooking recipes in American sources |
| Area | 1 hectare | Land plots, real estate, agriculture |
| Speed | 100 km/h | Traffic, sports, vehicle specifications |
| Digital Storage | 1 GB | Storage, data plans, file size |
What is unit conversion
The same physical quantity (a distance, a weight, a temperature) can be expressed in different measurement systems — metric (meter, kilogram, Celsius, used across most of the world) and imperial/US customary (inch, pound, Fahrenheit, used mainly in the US). Converting means rewriting the same real value under a different unit, never changing the quantity itself: 1 inch and 2.54 centimeters are exactly the same distance, just described two ways. Six of the seven categories in this tool convert by a fixed factor (multiply/divide); Temperature is the exception — Celsius, Fahrenheit and Kelvin don't share a common factor, the conversion also involves adding/subtracting an offset (see "Limitations", below).
Limitations
No Time, Pressure or Energy in this version — categories with more occasional real-world use, out of scope for this first batch. Digital Storage uses the decimal convention (1 KB = 1000 bytes, the same used by modern operating systems and storage vendors), not binary (1 KiB = 1024 bytes) — both conventions coexist in practice, and only decimal is available here. Displayed values are rounded to 10 significant digits (enough to eliminate floating-point noise without losing real precision); conversions between a very large value and a very small unit of the same category (e.g., 1 byte in petabytes) may show up in scientific notation.
Frequently asked questions
The previous source unit wouldn't even exist as an option in the new category ("km" makes no sense in Mass, for example) — keeping the value would be an invalid state, not a useful reinterpretation. Switching only the unit within the same category (from "cm" to "km", for example) preserves the value on purpose: that's how you find out what "10" means in another unit, without retyping it.
In this tool, 1000 — the decimal convention (KB/MB/GB), the same used by modern operating systems and storage vendors. The binary convention (1 KiB = 1024 bytes) exists and is used in other contexts (e.g., how much RAM a program actually uses), but it isn't available in this version — see "Limitations".
Length, mass, volume, area, speed and digital storage convert by simple multiplication/division (e.g., 1 inch × 2.54 = centimeters). Temperature is different: 0 °C isn't "zero" in Fahrenheit (it's 32 °F) or Kelvin (it's 273.15 K) — the three scales have different zero points, so the conversion also needs to add or subtract an offset, not just multiply.
Yes, to 10 significant digits — enough to eliminate floating-point noise (e.g., "0.30000000000000004" instead of "0.3") without cutting real precision for any practical use. Conversions between very different magnitudes (e.g., 1 byte converted to petabytes) may show up in scientific notation.
The Length category uses the land mile (1609.344 m), the most common in everyday use (highways, distances). The nautical mile doesn't have its own unit here, but the knot (Speed category) is already defined from it — 1 knot equals exactly 1 nautical mile per hour.
A deliberate scope decision for this first version — the seven available categories cover the most common day-to-day use for someone developing software. Time, Pressure and Energy remain a possible future addition, not an oversight.