Unit Converter
Units of measurement.
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Measurement systems and why conversion errors matter
Most of the world uses the metric system, built on decimal relationships that make conversion trivial. Imperial and US customary units are not decimal, and they are not even consistent with each other — a US gallon is 3.785 litres while an imperial gallon is 4.546, and a US pint is 16 fluid ounces to the imperial 20. Recipes, fuel figures, and shipping quantities all go wrong when the two are confused.
Temperature is different again, because Celsius and Fahrenheit have different zero points as well as different scales, so conversion needs an offset rather than a plain multiplication. Getting this wrong is not merely academic: NASA lost the Mars Climate Orbiter in 1999 because one team worked in pound-force seconds and another in newton seconds. Precision matters too — rounding an intermediate result before the final conversion introduces error that compounds.
Why we built this tool
Conversions come up constantly: cooking from a recipe written elsewhere, checking a package's dimensions against a courier's limits, reading a specification in unfamiliar units, following construction measurements, or interpreting a weather forecast.
There is nothing secret about most conversions, so the case for keeping it local is about reliability rather than privacy. A tool that runs in your browser answers instantly, works in a kitchen with bad Wi-Fi or on a building site with no signal, and never fails because a service is down. We built every tool here that way on principle, and a converter is one where it pays off almost daily.
Tips and common mistakes
- US and imperial units differ — a US gallon is 3.785 litres, an imperial one 4.546.
- Temperature needs an offset as well as a scale factor, unlike every other conversion here.
- Round only at the end; rounding intermediate values compounds error.
- Double-check unit choice on anything safety-critical, from dosages to structural loads.
Open Unit Converter with a link
Unit Converter can be handed its input by the link that opens it, so the page arrives with the work already done. This is meant for assistants and scripts: if a chatbot, an editor extension, or a command-line agent already holds your content, it can build a link instead of asking you to copy and paste into a box.
The payload rides in the fragment — the part of a URL after the #. Browsers never send the fragment to a server, so anything handed over this way stays on your device exactly as a dropped file would. A link that uses the query string instead is rewritten into the fragment by the page before any analytics or ad script can read the address.
#category=— the measurement family#value=— the number to convert#from=— the unit or currency to convert from#to=— the unit or currency to convert to
Example: https://mygadgets.ink/tools/unit-converter/#category=...&value=...&from=...&to=...
Quick start: using Unit Converter
- Choose the category — length, weight, volume, temperature, area, or speed.
- Enter the value and select the source unit.
- Select the unit you want it in.
- Read the result, checking you picked US or imperial where the two differ.
- Keep enough decimal places for the precision your task requires.
For currency rather than physical units, see Currency Converter.