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Number to Words Converter

Spells out a number in English words using the short scale (thousand, million, billion, trillion), gives the ordinal form for whole numbers, and, for amounts of money, the spoken and cheque-writing forms with dollars and cents.

When to use

You need a number written in words for a cheque, contract, invoice or text, or the ordinal form (e.g. 'twenty-first') of an integer.

Do not use when: You need Roman numerals (use roman-numeral), a different language, or the long scale (milliard/billion) used in some European languages.

Formula

Digits are grouped in threes from the right; each non-zero group is read as hundreds/tens/units followed by its short-scale name (10^3 thousand, 10^6 million, 10^9 billion, 10^12 trillion, 10^15 quadrillion); cents = round(fraction × 100)

American English conventions: no 'and' between hundreds and tens ('one hundred five'), hyphens in twenty-one to ninety-nine; the fractional part is read digit by digit after 'point'. Cheque style follows the common US form 'Amount and cc/100 dollars'.

Inputs

Parameter	Type	Unit	Required	Description
`number`	number		yes	The number to spell out, up to ±10^15 (one quadrillion); decimals are read digit by digit, or as cents when currency is true. Range: ≥ -1000000000000000, ≤ 1000000000000000
`currency`	boolean		default false	true to also return the amount as dollars and cents (spoken and cheque style).

Outputs

Output	Type	Description
`words`	string	Cardinal words, e.g. 'one thousand two hundred thirty-four point five six'; negatives start with 'minus'.
`ordinal`	string	Ordinal words such as 'one thousand two hundred thirty-fourth' (whole numbers only).
`currency_words`	string	e.g. 'one thousand two hundred thirty-four dollars and fifty-six cents' (only when currency is true).
`cheque_words`	string	e.g. 'One thousand two hundred thirty-four and 56/100 dollars' (only when currency is true).
`integer_part`	string	The digits before the decimal point.
`scale`	string	The highest scale needed: 'units', 'thousand', 'million', 'billion', 'trillion' or 'quadrillion'.

Example

1234.56 as currency: {"number":1234.56,"currency":true} → {"words":"one thousand two hundred thirty-four point five six","currency_words":"one thousand two hundred thirty-four dollars and fifty-six cents","cheque_words":"One thousand two hundred thirty-four and 56/100 dollars","integer_part":"1234","scale":"thousand"}

123456789: {"number":123456789} → {"words":"one hundred twenty-three million four hundred fifty-six thousand seven hundred eighty-nine","ordinal":"one hundred twenty-three million four hundred fifty-six thousand seven hundred eighty-ninth","integer_part":"123456789","scale":"million"}

GET https://tttkmbb.com/api/v1/calculate/number-to-words?number=1234.56&currency=true

Machine access

API: GET https://tttkmbb.com/api/v1/calculate/number-to-words (query parameters) or POST with a JSON body {"inputs": {...}}
Schema: https://tttkmbb.com/api/v1/calculators/number-to-words · Markdown: https://tttkmbb.com/math/number-to-words.md · JSON definition: https://tttkmbb.com/math/number-to-words.json
MCP: server https://tttkmbb.com/mcp, tool run_calculator with calculator_id="number-to-words"
OpenAPI operationId: convert_number_to_words
Freshness: static. Authentication: none. Rate limit: fair use (see rate limits).

Sources

Wikipedia – English numerals (reference)
Wikipedia – Long and short scales (reference)
Wikipedia – Names of large numbers (reference)

FAQ

Is 'and' inserted, as in British English?

No. The output follows American usage ('two hundred five'); add 'and' after 'hundred' yourself for British style ('two hundred and five').

How are cents rounded?

The fractional part is rounded to the nearest cent (half up), so 1234.565 becomes 1234.57; 100 cents carry into the dollar amount.

Which scale is used for billion?

The short scale: billion = 10^9, trillion = 10^12, quadrillion = 10^15, as in modern English usage worldwide.

Related calculators

Roman Numeral Converter — Another way of writing integers.
Rounding Calculator — Round a value before spelling it out.
Number Base Converter — Digits of a number in other bases.