number_format() & money_format()

Also Known As

TL;DR

Explanation

number_format(float $num, int $decimals, string $decimal_separator, string $thousands_separator) converts a float to a formatted string. The defaults produce English-style formatting (1,234.56), but all separators are configurable for locale-specific output (1.234,56 for German). money_format() was a thin wrapper around the C library strfmon() — locale-dependent, not available on Windows, and removed in PHP 8.0. The modern replacement is NumberFormatter from the Intl extension, which handles currency symbols, locale rules, and sign conventions correctly. For simple price display without Intl, number_format() with explicit separators is safe and predictable.

Common Misconception

Why It Matters

Common Mistakes

• Using money_format() in code targeting PHP 8+ — it was removed; replace with NumberFormatter::formatCurrency() or number_format() with explicit separators.
• Storing number_format() output in a database — it adds commas and periods that break numeric operations; always store raw numbers, format only for display.
• Using number_format() for locale-sensitive output without configuring separators — the defaults are English-style regardless of server locale.
• Passing a string to number_format() — it silently coerces to float, which can lose precision for large integers; use intl NumberFormatter for arbitrary precision.
• Formatting floats for financial calculations — floats have precision errors; use bcmath or integer cents and format only at display time.

Code Examples

<?php
// ❌ Raw float output — no thousands separator, inconsistent decimals
$price = 1234.5;
echo $price;              // '1234.5' — missing separator, missing trailing zero
echo round($price, 2);   // '1234.5' — still no formatting

// ❌ money_format() — removed in PHP 8.0
echo money_format('%.2n', $price); // Fatal error on PHP 8+

<?php
// ✅ number_format() — simple, predictable
$price = 1234.5;
echo number_format($price, 2);            // '1,234.50'
echo number_format($price, 2, ',', '.');  // '1.234,50' — German style
echo '$' . number_format($price, 2);      // '$1,234.50'

// ✅ NumberFormatter (Intl) — locale-correct currency
$fmt = new NumberFormatter('en_US', NumberFormatter::CURRENCY);
echo $fmt->formatCurrency(1234.5, 'USD'); // '$1,234.50'

$fmt_de = new NumberFormatter('de_DE', NumberFormatter::CURRENCY);
echo $fmt_de->formatCurrency(1234.5, 'EUR'); // '1.234,50 €'

References

• ↗ https://www.php.net/number_format
• ↗ https://www.php.net/class.numberformatter

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