BigInt & Large Numbers

to-words accepts bigint and precision-preserving string input, so you can safely convert values far beyond Number.MAX_SAFE_INTEGER without rounding or truncation.

BigInt Example

import { ToWords } from 'to-words';

const tw = new ToWords({ localeCode: 'en-US' });

tw.convert(1000000000000000000n);
// "One Quintillion"

tw.convert('9007199254740993');
// "Nine Quadrillion Seven Trillion One Hundred Ninety Nine Billion..."

// Indian system
const hi = new ToWords({ localeCode: 'hi-IN' });
hi.convert(100000000000000000n);
// "एक शंख"

String Input For Precision

const tw = new ToWords({ localeCode: 'en-US' });

tw.convert('9007199254740993');
tw.convert('1000000000000000000000');

Use string input when the value came from a database, finance system, or API and must remain exact.

Large-Number Systems

• en-US and most western locales use short scale
• de-DE and fr-FR use long scale wording such as Milliarde and Milliard
• hi-IN, ta-IN, and ur-PK use lakh / crore style grouping
• ja-JP, zh-CN, and ko-KR use East Asian units such as 万, 億, and 兆

When To Use BigInt vs String

• Use bigint when your app already holds whole numbers as integers
• Use string when decimal precision or trailing zeros matter
• Use plain number only when the value is safely within JavaScript integer limits and fractional precision is not critical

Related

• Indian numbering locales
• Japanese locale
• API Reference