Number to Words Converter

The naming rules the tool follows

• Digits are grouped in threes from the right and each group is read as a number from one to nine hundred ninety-nine followed by its scale word: thousand, million, billion, trillion or quadrillion (the short scale used in modern English).
• Groups that are all zeros are skipped, so 1,000,005 becomes one million five.
• Compound numbers from twenty-one to ninety-nine are hyphenated: forty-two, ninety-nine.
• No and is inserted after hundred, which is the American convention: 105 is one hundred five rather than one hundred and five.
• A decimal part is read digit by digit after the word point, so 3.14 is three point one four, not three point fourteen.
• Negative numbers are prefixed with negative rather than minus, and 0 is simply zero.

Scale words and the upper limit

The largest whole number the tool will spell is 9,007,199,254,740,991, JavaScript's safe-integer limit (2^53 − 1). It reads as nine quadrillion seven trillion one hundred ninety-nine billion two hundred fifty-four million seven hundred forty thousand nine hundred ninety-one. Anything larger shows a dash and the message Enter a valid number. The box also accepts exponent notation, so 1e6 is spelled as one million and 2.5e-7 as zero point zero zero zero zero zero zero two five.

Sample outputs

Cheques, invoices and legal documents

Cheque conventions differ from the tool's plain reading. The pence or cents part is normally written as a fraction, and no currency word is added automatically, so for $105.50 take one hundred five from the tool and finish it as one hundred five and 50/100 dollars by hand. British and Commonwealth documents usually insert and after the hundreds (one hundred and five pounds), which you would also add yourself. The copy button capitalises the first word, which suits the start of an amount line on an invoice or contract.

Edge cases and precision

• The decimal part is read from the digits exactly as you typed them, so trailing zeros are kept: 2.50 becomes two point five zero and 1.10 becomes one point one zero, which is what a cheque or an invoice needs.
• Very small fractions are spelled digit by digit without loss: 0.0000001 becomes zero point zero zero zero zero zero zero one, because the tool reads the typed digits rather than a value that the computer would otherwise store in exponent form.
• Roughly fifteen significant digits survive. 12345678.123456789 is stored as 12345678.12345679 and spelled with that final nine.
• There is no British spelling option, no ordinal form (first, second) and no currency mode; the output is always cardinal words.