Unit Converter
100% private — runs on your device, never uploaded. Works offline once loaded.
Convert between common units of length (m, km, mi, ft), weight (kg, lb, oz), temperature (°C, °F, K) and data size (B, KB, MB, GB). Everything runs locally in your browser.
What's happening behind each conversion
Length, weight and data conversions all work the same way: every unit is defined by a fixed factor against a base unit (meters for length, grams for weight, bytes for data), so converting miles to kilometers is really just multiplying by a constant (1 mile = 1.609344 km exactly). Temperature is the odd one out — Celsius, Fahrenheit and Kelvin don't share a common zero point, so converting between them needs an offset formula, not a simple multiplier (°F = °C × 9/5 + 32, while Kelvin starts at absolute zero, -273.15°C).
Everyday situations this solves
Most mix-ups happen at the boundary between the US customary system and the metric system used almost everywhere else, or between how storage is marketed versus how your OS reports it.
- Following a US recipe in ounces and cups when your kitchen scale reads grams
- Checking a courier's weight limit listed in kilograms against a suitcase weighed in pounds
- Converting a US weather forecast in °F for a trip to a country that uses °C
- Figuring out why a '512 GB' drive shows less free space than expected in your file explorer
Why storage units are the most confusing of all
Traditionally, 1 KB meant 1024 bytes because computers count in binary powers of two — that's the convention operating systems and this converter use for KB/MB/GB. Hard drive and SSD manufacturers, however, market capacity using the decimal definition (1 KB = 1000 bytes), which is why a drive labeled 1 TB shows up as roughly 931 GB in your operating system — no storage is missing, it's two different definitions of the same unit name.
A tip on precision
For unit families like length and weight, the conversion factors are mathematically exact, so results are as precise as the decimal places you need. For temperature, avoid rounding the intermediate value before converting again — round only your final answer, since chaining rounded conversions (say °F → °C → K) can drift by a degree or more over several steps.
Frequently asked questions
Are KB/MB binary or decimal?
Binary (1024-based) — standard for file sizes.
Is anything sent to a server?
No — conversion happens on your device.
Are KB/MB/GB conversions binary or decimal?
Binary (1024-based, also called KiB/MiB/GiB technically) — this matches how operating systems report file and memory sizes, which is the convention most people expect when converting data units.
Is any of my data sent to a server?
No — every conversion runs instantly on your own device using JavaScript, with no values ever transmitted anywhere.
Why isn't converting Celsius to Kelvin just a multiplication?
Celsius and Kelvin share the same size of degree but a different starting point — Kelvin's zero is absolute zero, so the conversion is an addition (K = °C + 273.15), not a scaling factor like most other unit pairs.
Is a UK ton the same as a US ton?
No — a US 'short ton' is 2,000 lb, a UK 'long ton' is 2,240 lb, and a metric tonne is 1,000 kg (about 2,204.6 lb), so double-check which one a source means before trusting a quick mental conversion.
Does this convert cooking measurements like cups to grams?
This tool covers length, weight, temperature and data size — cup-to-gram conversions vary by ingredient density (flour and sugar aren't the same weight per cup), so they need an ingredient-specific converter rather than a generic weight one.
How precise are the length and weight conversion factors?
They use the internationally defined exact factors (for example 1 inch = 2.54 cm exactly), so results are limited only by the number of decimal places displayed, not by any approximation in the underlying math.
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