1000 = M
1000 in Roman numerals is M.
One thousand written with the letters M.
1000 in words: One thousand
One thousand in Roman numerals is M, from the Latin mille, meaning thousand. It is the largest single symbol in the standard system, which is why the biggest plain numeral you can write is 3999 (MMMCMXCIX): once you need four thousands, the standard letters run out.
M anchors every year and large date you are likely to write, from MCMXCIX (1999) to MMXXV (2025). It also marks a millennium, a thousand years. Above three thousand the same M simply repeats, and beyond 3999 a bar over a letter (the vinculum) takes over.
How 1000 breaks down
Reading M from left to right, each group is added together to reach 1000:
| Group | Value | Place |
|---|---|---|
| M | 1000 | thousands |
| M | 1000 | total |
Frequently asked questions
What is 1000 in Roman numerals?
1000 in Roman numerals is M.
How do you write 1000 in words?
1000 is written "One thousand" in English.
What number comes before M?
The number before M is 999, written CMXCIX in Roman numerals.
What number comes after M?
The number after M is 1001, written MI in Roman numerals.
Related numbers
Last updated July 22, 2026. Reviewed for accuracy against the standard rules for Roman numerals.