Converters & Generators
Currency, unit, time zone and colour converters, plus password, random number, dice and spin-the-wheel generators.
Converters and generators: what is happening behind each one
This group is different from the rest of the site. A calculator applies a formula to your numbers; these tools convert between systems, or produce something new. The useful thing to know about each is where its data comes from and how much you should trust it.
Converting units, money and time zones
The unit converter handles length, weight, volume, temperature, area, speed and more in one place. Unit factors are fixed by definition, so these conversions are exact and will not change. Temperature is the odd one out: Celsius and Fahrenheit need an offset as well as a multiplier, which is why a temperature difference converts differently from a temperature reading.
The currency converter is the opposite case. Exchange rates move continuously and differ by source, so any rate you see here is a reference mid-market rate, not a quote. Your bank or card network will apply its own spread and fees, and the amount that lands in an account is routinely a percent or two away from the mid-market figure. Use this to sanity-check a quote, never to predict what a transfer will cost.
The time zone converter is where most scheduling errors happen, because offsets are political rather than geographic. Several countries shift their clocks for part of the year and others do not, so the gap between two cities is not a constant. India stays on a single offset all year, which means the difference to London or New York changes twice annually. When you book a call weeks ahead, convert for the actual date, not for today.
| Tool | Source of truth | How stable |
|---|---|---|
| Unit converter | Defined conversion factors | Permanent |
| Currency converter | Published market rates | Changes every minute |
| Time zone converter | Government time rules | Changes with the season |
Number systems and colour
The binary calculator converts between binary, decimal, octal and hexadecimal and performs arithmetic in each. If you are learning why computers use base two, converting a few familiar numbers by hand and checking them here is a faster way to understand place value than reading about it. The Roman numeral converter covers the standard range and follows the subtractive rule, where IV is four rather than IIII.
The colour picker gives HEX, RGB and HSL values for the same colour. HEX is the format CSS expects, RGB is the same information in decimal, and HSL is the one worth learning: it splits a colour into hue, saturation and lightness, so building a palette becomes a matter of holding the hue and moving the lightness, rather than guessing at hex digits.
Randomness, and what it is good for
The password generator builds a string in your browser from your chosen length and character set. Nothing is sent anywhere or stored. Length does more for strength than exotic symbols do, so a long passphrase beats a short, clever one, and a password manager beats remembering either.
For picking numbers or names, the random number generator gives a range with or without repeats, the dice roller replaces the dice your board game lost, and spin the wheel settles a decision between options you type in. These use your browser's random function, which is fine for games, raffles, classroom turns and choosing where to eat. It is not certified randomness, so do not use it for anything where money or fairness is formally at stake, such as a licensed lottery or a published statistical sample.
All 10 converters tools on CodingMarble Calculator are free, need no sign-up and work on mobile: Random Number Generator, Unit Converter, Roman Numeral Converter, Binary Calculator, Currency Converter, Time Zone Converter, Color Picker, Password Generator, Dice Roller, Spin the Wheel.
Last reviewed 2026-10-14 · How we check every calculator