printf()

The PHP printf() function outputs a string formatted according to a template. Unlike echo, which just concatenates and prints values as-is, printf() lets you control exactly how each value appears — its width, number of decimals, padding, sign, and number base — by inserting format specifiers (placeholders such as %s or %.2f) into a format string. This is the right tool whenever the layout of the output matters: aligned tables, money with two decimals, zero-padded IDs, or hex color codes.

This page covers the syntax, the anatomy of a format specifier, the most common conversions with runnable examples, and the closely related functions in the same family.

Syntax

printf(string $format, mixed ...$values): int

• $format — a template string containing literal text plus one or more format specifiers.
• $values — the values substituted into the specifiers, in order.
• Returns the number of characters written (the length of the output), not the string itself. printf() prints directly to output. If you want the formatted string returned instead of printed, use sprintf().

A basic example

%s is replaced by the first argument ($name) formatted as a string, and %d by the second ($age) formatted as a signed integer. The output is:

My name is John Doe and I am 35 years old.

Anatomy of a format specifier

Every specifier begins with % and may include optional parts in this order:

%[argnum$][flags][width][.precision]specifier

• flags — e.g. 0 (pad with zeros), - (left-justify), + (always show sign), ' ' (a space pads with that character).
• width — the minimum number of characters the field occupies.
• .precision — for floats, the number of digits after the decimal point; for strings, the maximum length.
• specifier — the conversion type (see below).

To output a literal percent sign, escape it as %%.

Common conversion specifiers

Width, precision, and padding

This is where printf() earns its keep. The example below formats a price to two decimals, zero-pads an ID to 5 digits, and renders a number as a hex color:

<?php
$price = 7.5;
$id = 42;
$color = 16711680; // red

printf("Price: $%.2f\n", $price);
printf("Order ID: %05d\n", $id);
printf("Color: #%06X\n", $color);
?>

Output:

Price: $7.50
Order ID: 00042
Color: #FF0000

%.2f forces exactly two decimals, %05d pads the integer with zeros to a width of 5, and %06X produces uppercase hex padded to 6 digits.

Argument swapping

A specifier can name which argument it uses with n$, so you can reuse a value or reorder arguments without changing the list — handy for translatable strings where word order differs by language:

<?php
printf('%1$s likes %2$s. %2$s likes %1$s too.', 'Ann', 'tea');
?>

Output:

Ann likes tea. tea likes Ann too.

The printf family

printf() belongs to a family of functions that share the exact same format syntax but differ in what they do with the result:

• sprintf() — returns the formatted string instead of printing it. Use it when you need to store or further process the result.
• vprintf() — like printf(), but takes the values as a single array (vprintf($format, $args)), useful when the arguments are already in an array.
• fprintf() — writes the formatted string to a stream/file handle rather than standard output.

For locale-aware number formatting (thousands separators, currency), see number_format() instead.

When to use it

Reach for printf() (or sprintf()) when output layout matters: aligned columns, fixed-decimal money, zero-padded identifiers, or generating strings like hex colors and URLs. For plain output where formatting is irrelevant, echo is simpler and faster.

Practice