About

About this site

I’m Mark, and I built this site in Australia because I like building useful tools.

Roman numerals looked like a simple job: seven letters and a few rules. The more I dug in, the more the details mattered. Why 1999 is MCMXCIX and not MIM? Why the same date can mean two different days depending on where you live? Why the clock on the wall says IIII when every textbook says IV? So I set out to build a converter that gets those details right and shows its working. Along the way I found a niche need: designing dates and clock faces for tattoos, so I included that as well.

I’m not a historian. I’ve tried to keep the explanations accurate, to be clear about where the history is uncertain, and to say so when a rule is modern rather than Roman.

What's here

• A converter that works both ways, with a step-by-step breakdown.
• A date converter that warns when day and month could be read the other way round.
• A tattoo lettering preview and a clock face generator, with downloads and real-size stencils.
• Guides, a printable chart and worksheets, and pages for every year from 1900 to 2100 and every number from 1 to 1,000.

How the content is checked

• Numerals are calculated, not typed. Every numeral on the site comes from the same conversion code, and automated tests check that every number from 1 to 3,999 converts there and back correctly.
• Year and number pages are built from facts about the number itself, such as its digits, factors and the calendar, so nothing on them is guessed.
• History is written carefully. Where something is a theory or a legend, such as why clocks use IIII, the guides say so. Where the modern rules differ from what the Romans actually did, they say that too.
• Photos are evidence, not decoration. Each one is openly licensed, checked by eye so its caption only describes what you can see, and credited where it appears.
• Fonts are open source and free to use for tattoos and products. See the credits.

Spotted a mistake?

If something here is wrong, unclear or missing, please tell me at [email protected]. Corrections are made as quickly as I can, and the guides show the date they were last updated.

Your privacy

Everything you type into the converters, date tool and previews is processed in your own browser. None of it is sent to me or stored. The site is funded by ads; the privacy policy explains how they use cookies.