Gera Tools

Number to Words Converter

Convert 42 to forty-two in English (and back)

Free number to words converter. Turn digits like 1234567 into English words and parse word-form numbers back into digits. Supports negatives and very large numbers. Runs in your browser. It runs free in your browser on Gera Tools, with nothing uploaded.

Last updated Source: Gera Tools

How large a number can it handle?

It uses arbitrary-precision integers, so it handles numbers up to the quintillions for the words output. The named scales are thousand, million, billion, trillion, quadrillion and quintillion.

What this tool does

This converter works in both directions: type a number like 1234567 and read it as “one million two hundred thirty-four thousand five hundred sixty-seven”, or type a phrase like “two thousand twenty six” and get 2026 back. Both fields update as you type. It is useful for writing cheque amounts, spelling out figures in legal documents, verifying how a number reads aloud, and generating word-form numbers for formal correspondence.

Number to words: how the conversion works

The integer is split into groups of three digits from the right, each group is named according to the short-scale magnitude words, and all groups are concatenated with their labels:

1,234,567
  → 1       "million"
  → 234     "thousand"
  → 567     (hundreds, tens, units)
  = one million two hundred thirty-four thousand five hundred sixty-seven

Within each three-digit group:

  • Hundreds: "X hundred" (e.g. "five hundred")
  • Tens 10–19: irregular forms (ten, eleven, twelve, thirteen … nineteen)
  • Tens 20–90: regular forms plus a hyphenated unit if needed ("forty-two", "seventy")
  • Groups equal to zero are skipped entirely

A leading minus sign produces "negative ...". Arbitrary-precision integers (BigInt) are used, so multi-billion values work without rounding.

Words to number: parsing the reverse

In the reverse direction, the phrase is tokenised word by word. Each token either:

  • Adds a small value (one to ninety-nine)
  • Multiplies the running sub-total by one hundred ("hundred")
  • Flushes the accumulated group into the total against a magnitude word ("thousand", "million", "billion", etc.)

The magnitude words in short-scale English are: thousand (10³), million (10⁶), billion (10⁹), trillion (10¹²), quadrillion (10¹⁵), quintillion (10¹⁸). The word "and" is ignored, so "one hundred and five" and "one hundred five" both yield 105.

The short scale versus the long scale

This converter uses the short scale — the system used in modern British English and American English — where:

  • 1 billion = 1,000,000,000 (one thousand million)
  • 1 trillion = 1,000,000,000,000

The long scale (historically used in continental Europe and older British English) defines billion as one million million. The difference matters when communicating with international counterparts or reading older texts.

Practical uses

  • Cheques and financial documents — banks in many countries require the amount in words as a fraud-prevention measure. The written form must exactly match the figures.
  • Legal contracts — consideration amounts and penalty figures are often written in both figures and words.
  • Formal letters and correspondence — amounts referenced in formal writing are conventionally spelled out when under approximately ten thousand.
  • Accessibility — screen readers speak number words more naturally than digit strings when text is authored correctly.

The tool handles whole integers only. For cheque amounts with pence or cents, convert the whole-number part here and add the fractional part separately (e.g. “forty-two pounds and 50 pence”).