UsefulTab
Converters & Units
Convert units of length, weight, temperature, color, and number bases.
12 tools in this category, all running locally in your browser.
Convert between units and formats instantly: length, weight, temperature, volume, area, speed, time, and data storage, plus number bases, timestamps, Roman numerals, and colors. Enter a value and the converted result updates as you type, with sensible defaults so common conversions are one step. Everything is computed in your browser, and nothing you enter is sent anywhere.
Length Converter
Enter a length in any unit and see it in metres, kilometres, miles, yards, feet, inches and more — live.
Weight Converter
Enter a weight in any unit and see it in kilograms, grams, pounds, ounces, stone and tonnes — live.
Temperature Converter
Enter a temperature in one scale and see it in Celsius, Fahrenheit and Kelvin at the same time.
Volume Converter
Enter a volume in any unit and see it in litres, millilitres, cubic metres, US gallons, quarts, pints, cups and fluid ounces — live.
Area Converter
Enter an area in any unit and see it in square metres, square feet, acres, hectares and more — live.
Speed Converter
Enter a speed in any unit and see it in metres per second, km/h, mph, knots and ft/s — live.
Time Duration Converter
Enter a duration in any unit and see it in seconds, minutes, hours, days and weeks — live.
Data Storage Converter
Enter a size in any unit and see it in bits, bytes, kilobytes, megabytes, gigabytes and terabytes — live.
Number Base Converter
Convert whole numbers between binary, octal, decimal, hexadecimal, and any base from 2 to 36 — live and locally.
Unix Timestamp Converter
Convert between a Unix epoch timestamp and a human date live, with ISO, local, and relative views.
Roman Numeral Converter
Type an Arabic number or a Roman numeral and see the other update live, with a symbol-by-symbol breakdown.
Color Converter
Convert a color between HEX, RGB, and HSL with a live swatch.
Conversion guides
How to convert colors between HEX, RGB and HSL, Unix timestamps into readable dates, and weights between metric and imperial units.
Convert weight between kg, lb, g, oz and stone
Kilograms to pounds, grams to ounces, stone to kg — convert any weight unit to every other one, live as you type.
Convert a Unix timestamp
Turn a Unix epoch number into a readable date and back — handling seconds vs. milliseconds and time zones — in your browser.
Convert HEX, RGB & HSL colors
What HEX, RGB, and HSL each mean, when to use which, and how to convert between them — in your browser.
Common questions
How accurate are the conversions?
The converters use standard conversion factors and update instantly. For everyday use they are precise; for scientific or legal precision, always verify against an authoritative reference.
Do the converters work offline?
Yes, once the page has loaded: conversions are calculated locally and keep working if your connection drops. A converter you have opened before also reopens offline in the same browser.
Can I convert number bases and colors too?
Yes. Beyond physical units, this category includes binary/hex/decimal base conversion, Unix timestamp conversion, Roman numerals, and color-format conversion.