Quick conversion! Your online roman numeral converter tool, switch from decimal to roman and vice versa, from roman to decimal easily.
Roman Numeral Converter
?
Numbers with an overline (e.g., V̅) represent that value × 1000. For example, V̅ = 5000
From decimal to Roman
–
I = 1, V = 5, X = 10, L = 50, C = 100, D = 500, M = 1000
Do you want to see other calculation tools?
The online calculator we offer is a roman numeral generator, even for large values. The roman numerals are I=1, V=5, X=10, L=50, C=100, D=500, and M=1000, you can convert decimal numbers to roman (Arabic to Roman numeral) or roman numbers to decimals.
To perform the conversion, you just have to enter the roman number or the decimal value you want to convert. The conversion will be done automatically.
How does the Roman numeral converter work?
The process for converter for roman numerals or date is simple and fast:
- Select conversion option
- Convert from decimal number to Roman (for example: 2025 becomes MMXXV)
- Convert from Roman number to decimal (for example: MMXXV becomes 2025)
- Optionally, there is a box that can be checked if you want to use the notation with upper lines (vinculum symbol), which is used to represent large numbers.
- Enter value
- Field to enter the number you want to convert.
- Result of the roman numeral conversion
- The tool will automatically proceed with the Roman numeral conversion showing the value
Additionally, when large values are calculated with the “vinculum” option, the application shows a reference table on roman numbers and their conversions to decimals.
How is the conversion from Roman numbers to decimals done?
When roman to numeral converter, it is important to consider the following rules to ensure the conversion is accurate:
1.- Value of symbols in Roman numbers. Each Roman symbol has a specific decimal value:
- I = 1
- V = 5
- X = 10
- L = 50
- C = 100
- D = 500
- M = 1000
2.- Addition rule. When a symbol of lesser or equal value follows one of greater value, the values are added. For example, VI = 5 + 1 = 6.
3.- Subtraction rule. When a symbol of lesser value precedes one of greater value, the value of the lesser symbol is subtracted from the greater. This rule has restrictions:
- I can only precede V and X.
- X can only precede L and C.
- C can only precede D and M.
For example, if we have the following conversion IV = 5 – 1 = 4 and IX = 10 – 1 = 9.
4.- Repetition of symbols. The symbols I, X, C, and M can be repeated a maximum of three times to add their values. For example, III = 3 and XXX = 30, and the symbols V, L, and D cannot be repeated.
5.- Order of symbols. A change in the order can significantly alter the value of the number. For example, VI is 6, but IV is 4, be careful!
6.- Large numbers. To represent large numbers, the Romans sometimes used a horizontal bar above a symbol (in mathematics it is called a vinculum symbol) to indicate that its value was multiplied by 1000. For example, the “V̅” with a bar above, represents 5000.
Examples of Roman numeral conversion
We provide some practical cases to better see how roman numbers are transformed into decimals or date:
- Example 1: Convert “XIV” to decimal
- First, we understand the Roman symbols; X = 10, I = 1, and V = 5
- First we see “X” (10). Then we see “I” (1) followed by “V” (5). According to the rules, when a smaller number is before a larger one, it is subtracted. So it would be; “IV” = 5 – 1 = 4.
- Now, we add the values: 10 (from X) + 4 (from IV) = 14, therefore, the result is: XIV = 14.
- Example 2: Convert “LXXIII” to decimal
- In this case, the values of the symbols are; L = 50, the value of X = 10, and I = 1.
- Now we have: First we see “L” (50). Then we see “XX” (10 + 10 = 20) and finally there is “III” (1 + 1 + 1 = 3).
- The sum of the values would be: 50 (from L) + 20 (from XX) + 3 (from III) = 73, therefore, the result is: LXXIII = 73.
- Example 3: Convert “CMXCIX” to decimal
- This case is more complex because the value is greater. The symbols are: C = 100, M = 1000, X = 10, and I = 1.
- Now we proceed to transform them step by step:
- First we see “CM”. Since “C” (100) is before “M” (1000), it is subtracted: 1000 – 100 = 900.
- Then we see “XC”. Since “X” (10) is before “C” (100), it is subtracted: 100 – 10 = 90.
- Finally, we see “IX”. Since “I” (1) is before “X” (10), it is subtracted: 10 – 1 = 9.
- The result of the sum of the values would be: 900 (from CM) + 90 (from XC) + 9 (from IX) = 999, therefore, the result is: CMXCIX = 999.
It is important to validate that the Roman number is well-formed, following the rules we have explained above, and you will have no problem.
Conversion table from decimal numbers to Roman
Below, we offer you a table of values converted from decimal numbers to roman so you can easily consult them:
| Decimal | Roman |
|---|---|
| 1 | I |
| 4 | IV |
| 9 | IX |
| 10 | X |
| 20 | XX |
| 30 | XXX |
| 40 | XL |
| 50 | L |
| 60 | LX |
| 70 | LXX |
| 80 | LXXX |
| 90 | XC |
| 100 | C |
| 200 | CC |
| 300 | CCC |
| 400 | CD |
| 500 | D |
| 600 | DC |
| 700 | DCC |
| 800 | DCCC |
| 900 | CM |
| 1000 | M |
| 2025 | MMXXV |
| 3999 | MMMCMXCIX |
| 10000 | X̅ (X with upper bar) |
🟧 Note: If you have any questions about using this roman numeral calculator, you can contact us from the contact section in the footer.
Frequently asked questions about converting Roman numbers – FAQ
What are the basic symbols of Roman numbers and their decimal values?
The values of the Roman number symbols are:
- I = 1
- V = 5
- X = 10
- L = 50
- C = 100
- D = 500
- M = 1000
How do I convert Roman numbers to normal numbers?
To convert Roman numbers to decimals, add the values of each letter according to their position. The values are: I = 1, V = 5, X = 10, L = 50, C = 100, D = 500, M = 1000. If a letter of lesser value is before a greater one (like IV), subtract them (5 – 1 = 4). If not, add them (like VI = 5 + 1 = 6). For example, XII = 10 + 1 + 1 = 12.
How are Roman numbers added?
When a symbol of lesser or equal value follows one of greater value, the values are added. For example, if we have “VI”, the conversion would be: VI = 5 + 1 = 6.
What does IV mean in normal numbers?
In Roman numbers, IV means 4. Because the I (1) is before the V (5), and when a smaller letter is before a larger one, it is subtracted: 5 – 1 = 4.
How are Roman numbers subtracted?
When a symbol of lesser value precedes one of greater value, the value of the lesser symbol is subtracted from the greater. For example: IV = 5 – 1 = 4. But there are some restrictions to follow:
- I can only precede V and X.
- X can only precede L and C.
- C can only precede D and M.
How do I know if I should add or subtract in Roman numbers?
You have to look at the order of the letters. If a smaller letter is to the left of a larger one (like IV, IX, XL), subtract them. If it is to the right or they are equal (like VI, XX), add them. For example, IX = 10 – 1 = 9, but XI = 10 + 1 = 11.
How much is XX in decimal numbers?
XX in Roman numbers is 20. Each X is worth 10, and since there are two, they are added: 10 + 10 = 20.
How much is the Roman number VII?
The Roman number VII is 7. Broken down it would be: V = 5, I = 1, I = 1. Since the I’s are after the V, they are added: 5 + 1 + 1 = 7.
How many times can a Roman symbol be repeated?
The Roman symbols I, X, C, and M can be repeated up to three times. Example: III = 3, but the symbols V, L, and D cannot be repeated.
What happens if a symbol of lesser value is between two of greater value?
The Roman symbol of lesser value is subtracted from the greater symbol that follows it. The practical case would be: XIV = 10 + (5 – 1) = 14.
How are large Roman numbers represented?
For very large numbers, a horizontal bar was used above the Roman symbol to indicate that its value was multiplied by 1000. If we have the “V̅” with a bar above, it represents the value of 5000.
Why is the order of Roman symbols important?
The order of the symbols in Roman numbers is important because it changes the value of the number. Example, if we have VI it is 6, but if it is IV, the value is actually 4.
