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Number to Words Converter
Type any whole number to see it spelled out in English words, ready for a check, invoice or contract.
How the number-to-words algorithm works
To spell out a large number, it's first split from the right into groups of three digits: ones, thousands, millions, billions and trillions. Each three-digit group is then converted to words separately, using the standard English words for one through nine, the teens (ten through nineteen), the tens (twenty through ninety) and the hundreds — joined with a hyphen where needed (like "thirty-four"). Finally, each group's scale word (thousand, million, billion or trillion) is appended after its words, and all the nonzero groups are strung together. This is exactly the format used when writing an amount out by hand on a check or invoice.
A worked example
Take the number 1,234,567. It splits into three groups: "1" (millions), "234" (thousands) and "567" (ones). The first group becomes "one" plus the scale word "million"; the second becomes "two hundred thirty-four" plus "thousand"; and the third becomes "five hundred sixty-seven". Putting the three parts together gives the final result: "one million two hundred thirty-four thousand five hundred sixty-seven".
Frequently asked questions
How does the number-to-words algorithm work?
A large number is first split from the right into groups of three digits: ones, thousands, millions, billions and trillions. Each three-digit group is then spelled out separately using the standard English words for ones (one to nine), the teens (ten to nineteen), tens (twenty to ninety) and hundreds — joined with hyphens where needed. Finally, each group's scale word (thousand, million, billion or trillion) is appended after it, and all the nonzero groups are joined together.
What number-naming system does this use?
This tool uses the US short scale, where each new scale name (thousand, million, billion, trillion…) is 1,000 times the previous one. This is the standard system in the US and increasingly worldwide, though some countries still use the long scale, where “billion” means a million million.
Can it handle negative numbers or zero?
Yes — zero is spelled “zero,” and negative numbers are prefixed with “negative.” Decimal numbers are not supported; only whole numbers are converted.
How large a number can I convert?
This tool supports whole numbers up to just under one quadrillion (15 digits). Anything larger would need the scale word list extended further.