Guide · 8 min read
Rules for Writing Numbers in Words (British English)
The complete rules for writing numbers in words: when to use "and", where hyphens go, commas in large numbers, and when to spell out numbers in formal writing.
Updated
Every number in English, however large, is written with about thirty words. The difficulty is not the vocabulary but the joins: where “and” goes, where a hyphen goes, and where nothing goes at all. This guide sets out the British English rules that NumWords follows, with the American differences noted where they matter.
The building blocks
You need three small sets of words.
| Set | Words |
|---|---|
| Units and teens (0–19) | zero, one, two, three, four, five, six, seven, eight, nine, ten, eleven, twelve, thirteen, fourteen, fifteen, sixteen, seventeen, eighteen, nineteen |
| Tens (20–90) | twenty, thirty, forty, fifty, sixty, seventy, eighty, ninety |
| Group words | hundred, thousand, million, billion |
Watch the spellings that catch people out: forty (no “u”), ninety (not “ninty”), eighteen and eighty (one “t”), twelve and fifteen (an “f”, not a “v”). The 1 to 100 chart lists every one.
Rule 1: “and” joins the hundreds to what follows
Inside any three-digit group, British English puts “and” between the hundreds and the tens or units that follow.
- 250 → two hundred and fifty
- 375 → three hundred and seventy-five
- 101 → one hundred and one
- 600 → six hundred (nothing follows, so no “and”)
The same “and” appears when the final part of a larger number is below one hundred, because there are no hundreds to attach it to: 1,005 → one thousand and five; 46,058 → forty-six thousand and fifty-eight.
American English generally omits this “and”: two hundred fifty, one thousand five. See British vs American English numbers.
Rule 2: hyphenate twenty-one to ninety-nine
When a tens word and a units word are combined, they take a hyphen: twenty-one, thirty-eight, ninety-nine. This is true wherever the compound appears: thirty-eight thousand, four hundred and sixty-two, ninety-nine million.
Nothing else is hyphenated. Do not write two-hundred or one-thousand, except when the whole number is used as an adjective before a noun (a two-hundred-page report).
Rule 3: thousands, millions and billions follow one another without “and”
Large numbers are read in three-digit groups from the left. Name each group, add its group word, and move on. There is no “and” between groups.
- 2,500 → two thousand five hundred (not two thousand and five hundred)
- 1,200,000 → one million two hundred thousand
- 367,752 → three hundred and sixty-seven thousand seven hundred and fifty-two
- 4,000,000,000 → four billion
Groups with nothing in them are simply skipped: 2,000,005 → two million and five (the thousands group is empty, and the final part is under one hundred, so Rule 1 adds “and”). The large numbers guide has more worked examples.
Rule 4: keep the group words singular
After a number, hundred, thousand, million and billion never take an “s”: six hundred, three thousand, two million pounds. The plural is only used when there is no number in front: hundreds of people, millions were spent.
Capitals and commas
- Running text: lowercase. The house sold for two hundred and fifty thousand pounds.
- Start of a sentence: capital first letter only. Thirty-eight people attended.
- Cheques and legal documents: either a capital first letter or Title Case, with “and” left lowercase: Two Hundred and Fifty Thousand Pounds.
- Commas: in the figures (250,000), not in the words.
Words or figures?
Style guides differ on the details, but the common ground is this:
| Use words | Use figures |
|---|---|
| Numbers one to nine (Oxford, Guardian, most newspapers) or one to ninety-nine (Chicago, many book publishers) | Larger numbers, and any list that mixes small and large numbers |
| Any number that begins a sentence | Measurements, percentages, ages, dates, times, page numbers |
| Round approximations: about a thousand people | Exact money amounts in running text: £2,500 |
| Cheques and contracts – words and figures together | Tables, statistics and technical writing |
Checklist before you sign anything
- Does every three-digit group with hundreds followed by tens or units have “and”?
- Is every compound from twenty-one to ninety-nine hyphenated?
- Is there no “and” directly after thousand, million or billion (unless the rest is under one hundred)?
- Are hundred, thousand and million singular?
- Do the words match the figures exactly?
Or skip the checklist: type the figure into NumWords and copy the result.
Frequently asked questions
Is it "one hundred and one" or "one hundred one"?
In British English it is "one hundred and one". American English usually writes "one hundred one". Both hyphenate compound numbers such as twenty-one.
Do you put a comma in numbers written as words?
Not normally. Commas belong in the figures (1,250,000), not in the words. Some legal drafters add commas between groups ("one million, two hundred and fifty thousand") but it is optional and increasingly rare.
When should I use words rather than figures?
Most style guides spell out numbers from one to nine (some say up to one hundred) and any number that begins a sentence. Use figures for larger numbers, measurements, percentages, dates and money in running text, and give both words and figures on cheques and in contracts.
Is "a hundred" the same as "one hundred"?
They mean the same. "A hundred" and "a thousand" are fine in speech and informal writing; formal documents and cheques use "one hundred" and "one thousand".