How Numbrate Converts Numbers to Words: Accuracy, Limits and Design
A behind-the-scenes look at what happens between typing a number and seeing the words, and the choices made to keep the result trustworthy.
1. Reading what you typed
Before conversion, the input is normalised in your browser. Thousands separators (1,234,567 or 1.234.567 or 1 234 567), decimal commas, minus signs and native digits such as Arabic-Indic or Devanagari numerals are recognised. Ambiguous input like 1,234 is resolved using the language of the page, because the same characters mean different things in different countries. The page shows a confirmation line (“= 1,234.56”) so you can see how it was understood.
2. One engine per rule set
The conversion itself runs on the server with one section per language. Each section knows its own scale words, joining words, gender and plural rules. The engine does not translate English output; it builds the number from the language’s own grammar.
3. Size and precision
- Whole numbers of up to 36 digits.
- Up to 20 decimal places.
- Values are handled as decimal strings, not floating-point numbers, so large values do not lose digits.
4. Reject, do not round
If a number is out of range, or a currency amount has more decimals than the currency allows, the converter returns an error. For example, 1234.567 USD is refused because dollars have two decimal places. A converter that rounds silently would produce correct-looking words for the wrong amount, which is worse than showing an error.
5. Tested language by language
Every language has golden tests: fixed inputs with the expected output written by hand and checked against the language’s rules. When a user reports a mistake, the correct form is added as a new test so the problem cannot return.
6. Privacy
The number you enter is sent to the conversion API, converted, and returned. Numbrate does not store it or link it to you. Details are in the Privacy Policy.
7. Where else it runs
The same engine behind this website is used in the Google Sheets add-on and the developer API.
Found an error in a language you speak? Please send us the input and the correct output.
Frequently asked questions
How many digits can Numbrate convert?
Whole numbers of up to 36 digits and up to 20 decimal places.
Does Numbrate store the numbers I type?
No. Values are converted on request and not stored.