Roman numerals still appear everywhere-front matter in books, outlines, appendices, monarchs (e.g., Elizabeth II), centuries, and research numbering. This converter supports the standard range (1–3999) with strict subtractive rules (IV, IX, XL, XC, CD, CM), and an extended overline mode for larger values (overline means ×1000, so V = 5000).
Helpful companions: clean pasted numerals with the Whitespace & Formatting Cleaner, remove stray blank lines via Remove Empty Lines, restructure lists using the Text ↔ List Converter, and verify lengths with the Word & Character Counter. If your manuscript includes units, format them with the Unit Converter.
What the Roman Numeral Converter does
- Arabic ↔ Roman conversion: Type a number or a Roman numeral and get the result instantly.
- Strict mode validation: Enforces legitimate subtractive pairs and repetition limits (I/X/C/M up to 3 times; V/L/D never repeat).
- Extended overlines: Use overlines to represent ×1000 for large values needed in research or archival contexts.
- Live hints: Clear error messages for invalid characters or sequences.
- Copy & history: One-click copy and a local history panel for recent conversions (export as JSON).
- Private by design: Everything runs in your browser-no uploads.
Quick start
- Open the Roman Numeral Converter.
- Choose a direction: Arabic → Roman or Roman → Arabic.
- Toggle Strict rules or Overline mode if needed.
- Press Enter to convert and use the copy button to paste results into your document or outline.
- Review recent conversions in the history panel and export them as JSON if you want a record.
Examples that work well
- Book or thesis front matter: i, ii, iii… for prefaces and acknowledgments.
- Outlines & headings: I, II, III for high-level sections; A, B, C for subheads (pair with the Quick Table Generator to publish structured outlines).
- Historical labels: Monarchs and centuries (e.g., Henry VIII, the XX century).
- Figures & plates: Convert quickly while writing-keep a Duplicate Word Finder tab open to clean up repeated text.
Clean input, consistent output
Good results come from tidy source text. Normalize spaces with the Whitespace Cleaner, remove blanks via Remove Empty Lines, and use the Text ↔ List Converter to batch-edit Roman-labeled lists. For symbol lookups (e.g., Unicode variations), try Symbol & Character Info.
Formatting & style tips
- Case: Use uppercase Romans (I, V, X, L, C, D, M) for headings and formal numbering.
- Overlines: Only use overlines when required by your style guide or domain-otherwise stick to standard values up to 3999.
- Consistency: Apply the same rule set across your entire manuscript or presentation.
Frequently asked questions
- What is strict subtractive notation?
- Strict rules allow only specific subtractive pairs (IV, IX, XL, XC, CD, CM) and limit repetitions to keep numerals canonical and unambiguous.
- How do overlines work?
- An overline multiplies the value by 1000. For example, overlined V equals 5000. In the tool, enable extended mode to output overlined characters.
- Can I paste numerals with odd spacing?
- Yes-clean them first with the Whitespace & Formatting Cleaner or Remove Empty Lines and try again.
- Does the converter accept lowercase?
- Yes. Input can be upper or lower case; output is standardized.
Related tools & guides
- Guide: CSV to Responsive HTML Tables for publishing number-indexed lists.
- Citations 101 with BibTeX for accurate references in research documents.
- Symbol & Character Info to explore Unicode code points and names.
- Word & Character Counter to stay within submission limits.