Number to Words Converter

Writing a figure out in words is a legal habit before it is a typographic one: a cheque, a contract and an invoice all repeat the number in prose so a stray digit cannot change the amount unnoticed. Number to Words handles that in 3 registers, plain words, ordinals and currency, with 5 currency names to choose between.

The conversion splits the number into groups of 3 digits and names each group, so 1234567 comes back as One Million, Two Hundred Thirty Four Thousand, Five Hundred Sixty Seven. Commas separate the groups and the style is American, meaning no and between hundreds and tens. Type the digits with commas if you like; they are stripped before parsing.

Eight example chips run along the bottom, from 0 through -7 and 99.99 to 1,234,567,890, which between them exercise every branch including the two that produce errors. Everything is arithmetic in the page with no lookup service behind it.

Worked Example: Reading Out an Invoice Total

Select currency, leave the dropdown on Dollars and type 1204.50. The card returns One Thousand, Two Hundred Four Dollars and Fifty Cents. Cents are derived by rounding the fractional part to 2 places, and the carry is handled properly: enter 19.995 and you get Twenty Dollars, not the nonsensical Nineteen Dollars and One Hundred Cents. Switch the dropdown to Rupees and only the noun changes, since no exchange rate is involved anywhere.

Precision, Rounding and the Ceiling

• The ceiling is 999,999,999,999,999. Go past it and you get Number too large (max: 999 Trillion), because beyond roughly that magnitude a JavaScript number can no longer represent every integer exactly.
• words mode refuses decimals outright with Words mode only supports whole numbers and points you at currency mode, rather than silently truncating 99.99 to Ninety Nine as an earlier build did.
• ordinal mode needs a positive whole number and answers Ordinal requires a positive integer otherwise. It handles the irregular forms, so 12 gives Twelfth, 20 gives Twentieth and 21 gives Twenty First.
• Only currency mode accepts a fractional part, and it rounds to the nearest cent. A third of a dollar entered as 0.333 reports Thirty Three Cents.
• Anything unparseable returns Please enter a valid number. beneath the field, and negative values are spoken with a leading Negative in both words and currency modes.