Names for ordinal numbers in English

Formation and common spelling changes

The basic pattern is to convert a cardinal number into its ordinal form. In many cases this means adding -th to the cardinal word (four → fourth). A small set of ordinals are irregular in form; these are historical survivals from Old English and related Germanic forms:

• first (from one)
• second (from two)
• third (from three)
• fifth (from five; spelling changes to fth)
• twelfth (from twelve; ve → fth)

Other regular spelling adjustments occur when a cardinal ends in -y: the -y typically changes to -ieth (twenty → twentieth, thirty → thirtieth). If a cardinal ends with a silent e, the e is usually retained or altered according to standard spelling (nine → ninth, where the final e is dropped).

Numbers written with numerals and suffixes

Ordinals are often written with the numeral followed by a two-letter suffix: 1st, 2nd, 3rd, 4th, etc. The correct suffix depends on the last digit except for the teen exceptions. A practical rule is:

• If the last two digits are 11, 12, or 13 → use -th (11th, 12th, 13th).
• Otherwise, if the last digit is 1 → -st; 2 → -nd; 3 → -rd; all others → -th.

Compound ordinals (21–99) and hundreds

For compound numbers between twenty-one and ninety-nine, form the ordinal by making only the units part ordinal and joining with a hyphen: twenty-first, sixty-fourth, ninety-ninth. The tens part remains in its cardinal form (twenty, thirty, forty, etc.).

For numbers from 100 up to 999, state the number of hundreds first. If the number is an exact hundred, add -th to "hundred" (two hundredth, three hundredth). If there is a remainder, say "hundred" then the remainder as an ordinal or mixed form. Usage differs between varieties of English: many speakers say "one hundred and first" while others prefer "one hundred first." Examples:

• 101 → one hundred (and) first
• 175 → one hundred seventy-fifth (or one hundred and seventy-fifth)
• 512 → five hundred twelfth

Usage notes and style

When writing formally, spell out ordinals in full in prose or follow a house style for numerals and superscripts (e.g., "1st" with superscript letters in print). Dates often use numeric ordinals (June 1st) or the fully written form (the first of June). Centuries and decades are usually expressed with ordinals (the 21st century, the 1990s). For further guidance on punctuation and regional preferences, consult a style manual or online reference: style guide and usage notes.

Historical note and notable facts

Ordinals in English come from Old English and earlier Germanic formations; the modern irregulars reflect older roots and sound changes. The numeric-suffix convention (1st, 2nd) is a practical shorthand that arose with printing and typesetting and is now standard in many contexts, although some formal prose still prefers the full written form.