Number to Words Converter (English)

Understanding the number to words converter — concept and principle

This converter spells out a number in English words, such as 1,234,567 as "one million two hundred thirty-four thousand five hundred sixty-seven". It is useful for writing cheques, contracts and invoices where the amount must also appear in words, and for learners reading large numbers aloud. A second line gives a cheque-style version with the cents written as a fraction of 100.

How it is calculated

1. The whole-number part is split into groups of three digits from the right: units, thousands, millions, billions and trillions (the short scale, where 1 billion = 10⁹ and 1 trillion = 10¹²).
2. Each three-digit group is written as "[digit] hundred" followed by the last two digits. Numbers below 20 have their own names (eleven, twelve, … nineteen); 21 to 99 combine a tens word with a units word using a hyphen (sixty-seven).
3. Each non-zero group is followed by its scale word, and empty groups are skipped, so 1,000,005 is "one million five".
4. Negative numbers start with "minus". In the cheque line, the decimal part is rounded to two digits and shown as "and 00/100".

The input accepts up to 15 digits, which covers values below one quadrillion.

The principle

English, like most European languages, names numbers in powers of 1,000. That is why digits are grouped in threes with commas: every comma corresponds to a new scale word. Inside each group, the pattern repeats exactly (hundreds, then tens, then units), so the whole number is just a sequence of small three-digit names with labels.

Worked example

1. Input: 1234567.
2. Groups from the right: 1 | 234 | 567, with scales million, thousand and units.
3. 1 → "one million".
4. 234 → "two hundred" + "thirty-four" → "two hundred thirty-four thousand".
5. 567 → "five hundred" + "sixty-seven".
6. Result: one million two hundred thirty-four thousand five hundred sixty-seven; cheque style adds and 00/100 because there is no decimal part.

How to read the result

The output uses American style without "and" between hundreds and tens. British English usually says "five hundred and sixty-seven"; both are correct in their own regions. On a cheque, the words are the legal amount, so they should match the figures exactly.

Common mistakes

• Writing "forty" as "fourty" or "ninety" as "ninty".
• Adding "s" to scale words after a number: "two million", not "two millions".
• Confusing the short scale with the long scale used in some languages, where a billion means 10¹².

Frequently asked questions

Is it "one hundred and five" or "one hundred five"?

American usage usually omits "and"; British usage normally includes it. Both are understood.

How do I write cents on a cheque?

Write the dollars in words followed by "and" and the cents as a fraction, such as "and 45/100".

What comes after trillion?

In the short scale: quadrillion (10¹⁵), quintillion (10¹⁸), sextillion (10²¹).

Sources: The Chicago Manual of Style, University of Chicago Press, chapter on numbers · Merriam-Webster Dictionary, entries "billion" and "trillion"