What does the Roman Numeral Converter do?

Convert between decimal numbers and Roman numerals (I, V, X, L, C, D, M). Both directions. All calculations are performed in your browser using official UK rates and thresholds.

How accurate are the results?

This calculator uses standard mathematical algorithms and provides results accurate to the precision shown. For very large numbers or high-precision requirements, results are rounded to a reasonable number of decimal places.

Can I use this for schoolwork?

Yes. This calculator is suitable for GCSE, A-level and university-level mathematics. It follows standard mathematical conventions used in UK education.

Roman Numeral Converter

Convert between decimal numbers and Roman numerals (I, V, X, L, C, D, M). Both directions.

Last updated: April 2026 · Source: BBC Bitesize — Roman numerals

Decimal to Roman

Number (1-3999)

MMXXV

Roman to Decimal

Roman Numeral

2025

I = 1

V = 5

X = 10

L = 50

C = 100

D = 500

M = 1000

Disclaimer

This calculator is provided for informational purposes only and should not be considered as financial or tax advice. All calculations are performed locally in your browser — no personal data is collected or sent to our servers. Rates and thresholds are sourced from HMRC and GOV.UK and are updated for the current tax year. Always verify results with HMRC or consult a qualified professional before making financial decisions.

How It Works

Roman numerals use seven symbols: I (1), V (5), X (10), L (50), C (100), D (500) and M (1,000). When a smaller numeral appears before a larger one, it is subtracted (e.g. IV = 4, IX = 9). Otherwise, values are added left to right.

This converter translates between standard Arabic numbers and Roman numerals for values from 1 to 3,999. Roman numerals are still used in the UK for clock faces, film credits, monarchs (Charles III), chapter numbering and dates on cornerstones.

Example: Converting 2026

2026 = MMXXVI
M = 1000, M = 1000, X = 10, X = 10, V = 5, I = 1
1000 + 1000 + 10 + 10 + 5 + 1 = 2026

Source: BBC Bitesize — Roman numerals

Frequently Asked Questions

What does the Roman Numeral Converter do?: Convert between decimal numbers and Roman numerals (I, V, X, L, C, D, M). Both directions. All calculations are performed in your browser using official UK rates and thresholds.
How accurate are the results?: This calculator uses standard mathematical algorithms and provides results accurate to the precision shown. For very large numbers or high-precision requirements, results are rounded to a reasonable number of decimal places.
Can I use this for schoolwork?: Yes. This calculator is suitable for GCSE, A-level and university-level mathematics. It follows standard mathematical conventions used in UK education.