Roman Numeral Converter – Numbers & Dates

Type a number and get its numeral, or paste a numeral and get the number — the converter auto-detects direction. Numbers are built by decomposing each decimal place into additive and subtractive groups: 87 splits into 80 = LXXX and 7 = VII, giving LXXXVII. Years follow the same path — 2026 = MM + XX + VI = MMXXVI — which is why film credits and building cornerstones parse so quickly once you know the six subtractive pairs (IV, IX, XL, XC, CD, CM). Reverse parsing scans left to right and subtracts when a symbol is smaller than its neighbor: in CDXCIV, CD = 400 and XC = 90 and IV = 4, totaling 494. The converter validates input, rejecting forms like IIII or IC, and displays the full symbol chart plus the place-value breakdown for every conversion.

1. 1

   Enter a value

   Type 87 or LXXXVII — the direction is detected automatically

2. 2

   Decompose by place

   Split the number into 1000s, 100s, 10s and 1s

3. 3

   Apply the symbol rules

   Use additive runs or the six legal subtractive pairs

4. 4

   Validate and chart

   Illegal forms are rejected; the symbol chart accompanies every result

• 1

  Only I, X and C subtract, and only from the next two larger symbols

• 2

  A symbol repeats at most three times: 40 is XL, never XXXX

• 3

  Standard range is 1–3999; larger values need vinculum overbars

• Writing 99 as IC instead of XCIX

• Placing a smaller symbol after a run and subtracting, e.g. misreading XIV as 6 — it is 14

• Using VV for 10 or LL for 100 — only I, X, C, M repeat

• Assuming numerals encode zero; there is no Roman zero