The Complete Ordinal Numbers Guide
Master the rules of 1st, 2nd, 3rd, and beyond. Learn how to correctly form and use ordinal numbers in dates, rankings, and everyday English grammar.
Check Your Ordinal Numbers
Enter any cardinal number below to instantly see its correct ordinal form, both in numeric and written formats.
Cardinal to Ordinal Checker
Instantly convert quantities into positions
Formation Rules
How to correctly build ordinal numbers
The Irregular Exceptions
The first three numbers are completely irregular: 1 becomes 1st (first), 2 becomes 2nd (second), and 3 becomes 3rd (third).
The Standard “-th” Rule
For numbers 4 through 20, simply add “-th” to the end of the cardinal number (e.g., 4 becomes 4th, 11 becomes 11th, 20 becomes 20th).
The “Y” to “Ieth” Change
For multiples of ten (20, 30, 40, etc.), the ending “y” changes to “i” before adding “eth”. For example, twenty becomes twentieth (20th), and fifty becomes fiftieth (50th).
Compound Numbers
For numbers above 20 that are not multiples of ten, only the final digit changes to its ordinal form. For example, 21 becomes 21st (twenty-first), and 99 becomes 99th (ninety-ninth).
Common Use Cases
Where to use ordinal numbers in everyday English
Ordinal Numbers Chart
A quick lookup table for the most commonly used ordinal numbers, showing the cardinal number, its numeric ordinal form, and its written equivalent.
| Cardinal Number | Ordinal (Numeric) | Ordinal (Written) |
|---|---|---|
| 1 (One) | 1st | First |
| 2 (Two) | 2nd | Second |
| 3 (Three) | 3rd | Third |
| 4 (Four) | 4th | Fourth |
| 5 (Five) | 5th | Fifth |
| 11 (Eleven) | 11th | Eleventh |
| 12 (Twelve) | 12th | Twelfth |
| 20 (Twenty) | 20th | Twentieth |
| 21 (Twenty-one) | 21st | Twenty-first |
| 30 (Thirty) | 30th | Thirtieth |
| 100 (One Hundred) | 100th | One Hundredth |
Ordinal Numbers FAQ
Answers to the most frequently asked questions about forming and using ordinal numbers in English.
An ordinal number is a number that indicates the position or order of something in a sequence, such as 1st, 2nd, 3rd, or 4th. This is different from a cardinal number, which indicates quantity (e.g., one, two, three).
Most ordinal numbers are formed by adding ‘-th’ to the end of a cardinal number (e.g., 4 becomes 4th). However, the first three are irregular: 1 becomes 1st (first), 2 becomes 2nd (second), and 3 becomes 3rd (third). For compound numbers like 21, only the last digit changes (21st, twenty-first).
In British English, dates are typically written with the ordinal indicator after the day, followed by the month and year (e.g., 1st January 2024 or 14th September 2026). In formal writing, it is often written as ‘the 14th of September’.
Yes. The numbers 1, 2, and 3 become ‘first’, ‘second’, and ‘third’ (not ‘oneth’, ‘twoth’, or ‘threeth’). Additionally, numbers ending in ‘y’ change to ‘ieth’ (e.g., twenty becomes twentieth, fifty becomes fiftieth), and five becomes fifth, twelve becomes twelfth.