Formatting Currency with Intl.NumberFormat in JavaScript

Intl.NumberFormat for Currency

The Intl.NumberFormat API is the standard way to format numbers as currency in JavaScript. It handles locale-specific formatting rules including symbol placement, thousands separators, decimal separators, and grouping automatically.

Basic Usage

// US Dollar in English
new Intl.NumberFormat("en-US", {
  style: "currency",
  currency: "USD",
}).format(1234.56);
// => "$1,234.56"

// Japanese Yen (0 decimals)
new Intl.NumberFormat("ja-JP", {
  style: "currency",
  currency: "JPY",
}).format(1234);
// => "￥1,234"

// Euro in German (comma as decimal separator)
new Intl.NumberFormat("de-DE", {
  style: "currency",
  currency: "EUR",
}).format(1234.56);
// => "1.234,56 €"

Key Options

Option	Values	Description
style	"currency"	Required for currency formatting
currency	ISO 4217 code	Required — "USD", "EUR", etc.
currencyDisplay	"symbol", "narrowSymbol", "code", "name"	How to show the currency
minimumFractionDigits	0–20	Minimum decimal places
maximumFractionDigits	0–20	Maximum decimal places
signDisplay	"auto", "never", "always", "exceptZero"	When to show +/- signs

Narrow vs. Wide Symbols

// "symbol" (default) — may use CA$ for disambiguation
new Intl.NumberFormat("en-US", {
  style: "currency",
  currency: "CAD",
  currencyDisplay: "symbol",
}).format(100);
// => "CA$100.00"

// "narrowSymbol" — always uses $
new Intl.NumberFormat("en-US", {
  style: "currency",
  currency: "CAD",
  currencyDisplay: "narrowSymbol",
}).format(100);
// => "$100.00"

Edge Cases

• Negative amounts: Different locales format negatives differently. en-US uses -$1.00, some locales use ($1.00) or 1.00- €
• Zero decimals: When formatting JPY, set maximumFractionDigits: 0 or let Intl handle it automatically based on the currency
• Large numbers: Intl.NumberFormat handles BigInt as of modern browsers
• Server-side: Available in Node.js 13+ with full ICU data