# 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.

- Calculator id: `number-to-words` · Category: Math (`math`) · Tool name: `convert_number_to_words`
- Canonical page: https://tttkmbb.com/math/number-to-words · This document: https://tttkmbb.com/math/number-to-words.md · JSON definition: https://tttkmbb.com/math/number-to-words.json

## Purpose

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.

**Use when:** 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.

## Input

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

## Output

| Field | Type | Unit | 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'. |

## 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'.

## Data Sources

- Wikipedia – English numerals — https://en.wikipedia.org/wiki/English_numerals (reference, retrieved 2026-09-24)
- Wikipedia – Long and short scales — https://en.wikipedia.org/wiki/Long_and_short_scales (reference, retrieved 2026-09-24)
- Wikipedia – Names of large numbers — https://en.wikipedia.org/wiki/Names_of_large_numbers (reference, retrieved 2026-09-24)

Data freshness: `static`. Deterministic formula with fixed constants; results never go stale. Inputs supplied by the caller determine the output.

## API

- `GET https://tttkmbb.com/api/v1/calculate/number-to-words?number=…`
- `POST https://tttkmbb.com/api/v1/calculate/number-to-words` with JSON body `{"inputs": {…}}`
- Response: unified envelope (`success`, `request`, `result.values`, `result.units`, `sources`, `freshness`, `timestamp`, `next_actions`, `links`); see https://tttkmbb.com/docs/response-format.md
- Schema: https://tttkmbb.com/api/v1/calculators/number-to-words · OpenAPI operationId `convert_number_to_words` in https://tttkmbb.com/openapi.json
- Authentication: none. Rate limit: fair use, see https://tttkmbb.com/docs/rate-limits.md.

## MCP

- Server: `https://tttkmbb.com/mcp` (Streamable HTTP, JSON-RPC 2.0, no auth)
- Tool:  `run_calculator` with `{"calculator_id": "number-to-words", "inputs": {…}}`

## Example

- 1234.56 as currency: inputs `{"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: inputs `{"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
```

## Limitations

You need Roman numerals (use roman-numeral), a different language, or the long scale (milliard/billion) used in some European languages. 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'. All values are computed from the formula above; no measurement or live data is involved.

## 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

- [Roman Numeral Converter](https://tttkmbb.com/everyday/roman-numeral.md) — Another way of writing integers.
- [Rounding Calculator](https://tttkmbb.com/math/rounding.md) — Round a value before spelling it out.
- [Number Base Converter](https://tttkmbb.com/math/base-converter.md) — Digits of a number in other bases.