Roman Numerals is the Android app people reach for when a film copyright line, a clock face, or a chapter heading throws a string of M, C and X at them. It converts both ways, handles numbers up to 3,999,999, and flags numerals that are written wrongly. We built Numeral Lab, a free converter that does the same job right here in your browser. No install, no ads, no signup. It also writes any date in numerals and ends with a 60-second quiz.
Convert numerals now
It opens on this year, already converted. Type a number, type a numeral, or tap the keypad, and the other side updates as you go. Switch to Dates for today’s date in numerals, or to Train for the quiz.
How to use it
On Convert, the number box and the numeral box are linked. Edit either one and the other follows, and a canvas below replays the conversion step by step: 1,994 becomes 1,000 + 900 + 90 + 4, then M, CM, XC, IV. On a phone, the keypad enters letters without opening the system keyboard. The Bar key puts an overline on the letters you type next, which multiplies them by 1,000, so I with a bar is 1,000 and the highest value is 3,999,999.
If you type something that is not standard, such as IIII or IC, the box tells you what it reads as and offers the standard form with one tap. Letters that are not numerals are named in the message, and zero is refused because the system has no zero.
Dates writes any calendar day as day, month and year in numerals, in three orders. Train runs 60 seconds of questions. Correct streaks multiply your points and add time, a wrong answer costs three seconds, and the daily set is the same for everyone on a given day. Your last number, best scores and day streak stay on your device. Nothing leaves your browser.
How it compares to Roman Numerals
The Android app has three parts: a converter, a Professor screen that explains the rules, and a quiz game with seven levels of ten questions. Numeral Lab keeps the converter, including the overline notation and the check for badly written numerals, and replaces the quiz with a quickfire round that gets harder as you go.
We added a few things the app does not advertise: dates, the animated breakdown that shows why a numeral is spelled the way it is, and a challenge link that lets a friend try the same daily questions. After a run, the Share button builds that link from your score.
We left out the Professor lesson text and the level-by-level campaign with its scoring rules. The app also has buttons to copy a result and clear the screen, and we did not rebuild those. Use Numeral Lab when you need an answer in seconds or want a short daily drill. Install the app if you want the full written guide to the rules, a structured course, or a converter that works from your home screen.
Get the full app
Roman Numerals on Android is free to download and adds the explanatory Professor screen and the seven-level quiz.
Frequently asked questions
How do I convert Roman numerals online without installing anything?
Use the converter above. Type a number to see its numeral, or type or tap a numeral to see the number. It works in any phone or laptop browser and needs no account.
How do you write numbers above 3,999 in Roman numerals?
Put a bar over a letter to multiply it by 1,000. So I with a bar is 1,000, V with a bar is 5,000, and 4,000 is I with a bar followed by V with a bar. Numeral Lab supports this up to 3,999,999 and draws the bars for you.
Is this the real Roman Numerals app?
No. Numeral Lab is an original tool inspired by the Roman Numerals app for Android and is not affiliated with its publisher. The real app has its own Professor lessons and quiz levels that we did not copy.
Does it work offline, and is it free?
It is free, with no ads or signup. Once the page has loaded it makes no further network requests, and your numbers, scores and streak stay saved in your browser.
