How to Spell Numbers in English

Rule 1 — hyphenate twenty-one to ninety-nine

The single most reliable rule in English number spelling is that the compound numbers from twenty-one through ninety-nine take a hyphen. That holds wherever they appear, including inside larger numbers: forty-two, one hundred twenty-three, three thousand four hundred fifty-six. You do not hyphenate the round tens (twenty, thirty), the teens (which already have single names), or the join between a digit word and “hundred”, “thousand” or “million”. So it is two hundred, never two-hundred.

Rule 2 — “and” is British, optional and only for the small group

American English omits the word “and” when spelling whole numbers: one hundred five, two thousand thirty. British English inserts “and” before the final tens-and-units part: one hundred and five, two thousand and thirty. Crucially, even in British usage “and” appears only once, before that last group — not between every scale word. In American usage, “and” is traditionally reserved for the decimal point or the cents on a cheque, which is why “a hundred and one dollars” sounds informal to American ears but perfectly normal to British ones.

Rule 3 — words or digits?

Most style guides agree on a threshold, even if they disagree on where it sits. The Chicago Manual of Style spells out whole numbers up to one hundred; the AP Stylebook spells out one through nine and uses figures from 10 up. Whatever guide you follow, three conventions are nearly universal:

• Spell out a number that begins a sentence, or rewrite the sentence so it doesn’t start with one.
• Use digits for dates, ages, percentages, money, measurements and anything technical.
• Be consistent within a passage — don’t write “five apples and 12 oranges” in the same list.

Rule 4 — the spellings people get wrong

A handful of number words cause most of the errors. Forty has no “u”, despite four and fourteen keeping theirs. Ninth drops the “e” from nine, and fifth and twelfth change shape from five and twelve. The ordinals first, second and third are irregular and look nothing like one, two and three. Whenever you’re unsure, the converter on this site gives you the canonical spelling instantly, in both cardinal and ordinal form.

Rule 5 — decimals, fractions and negatives

Read the part after a decimal point digit by digit: 3.14 is three point one four, not “three point fourteen”. Simple fractions are spelled with an ordinal denominator and a hyphen when used as adjectives — two-thirds full, a three-quarter turn. Negative numbers take “minus” or “negative” in front: minus seven. The converter handles all three automatically, so you can check any awkward case in a second.