Set Custom Image Size

Function Reference/add image size

Description

Registers a new image size. This means that WordPress will create a copy of the post thumbnail with the specified dimensions when you upload a new thumbnail.

Usage

<?php add_image_size( $name, $width, $height, $crop ); ?>

Parameters

$name
(string) (required) The new image size name.

Default: None
$width
(int) (optional) The post thumbnail width in pixels.

Default: 0
$height
(int) (optional) The post thumbnail height in pixels.

Default: 0
$crop
(boolean) (optional) Crop the image or not. False – Soft proportional crop mode ; True – Hard crop mode.

Default: false

Reserved Image Size Names

thumb, thumbnail, medium, large, post-thumbnail

The names “thumb” & “thumbnail” are just alias, so exactly the same.

However, if needed, you can always set the options yourself:

update_option('thumbnail_size_w', 160);
update_option('thumbnail_size_h', 160);
update_option('thumbnail_crop', 1);

Examples

A theme’s functions.php file.

if ( function_exists( 'add_theme_support' ) ) {
	add_theme_support( 'post-thumbnails' );
        set_post_thumbnail_size( 150, 150 ); // default Post Thumbnail dimensions   
}

if ( function_exists( 'add_image_size' ) ) { 
	add_image_size( 'category-thumb', 300, 9999 ); //300 pixels wide (and unlimited height)
	add_image_size( 'homepage-thumb', 220, 180, true ); //(cropped)
}

Crop Mode

Set the image size by resizing the image proportionally (that is, without distorting it):

add_image_size( 'homepage-thumb', 220, 180 ); // 220 pixels wide by 180 pixels tall, soft proportional crop mode

Set the image size by cropping the image (either from the sides, or from the top and bottom):

add_image_size( 'homepage-thumb', 220, 180, true ); // 220 pixels wide by 180 pixels tall, hard crop mode

Using the New Image Sizes

Within a theme’s template files.

<?php if ( has_post_thumbnail() ) { the_post_thumbnail( 'category-thumb' ); } ?>