Drupal - Basic: Website Image Size and Format Guide

Image Size and Format Guide

For image width dimensions (in pixels) for specific uses on our website, see the list at the end of this guide.

See the Images in Drupal guide for further information on how to upload and embed images.

Creating Images for the web

Speed is important!

Website visitors don’t care what format your images are in, they only care that they are viewable and downloaded in a timely fashion (even on slower connections). To accomplish this, images should be optimized for both speed and usability.

Image Mode: Use RGB format.

Image file format

JPG: Use this in most cases! This file type is good for saving images with millions of colors, including photographs and graphics with a variety of shades and gradients.

GIF: Best for line art/cartoon-like drawings.

PNG: Also an acceptable format, but not needed in most cases.

Please do not use other image file formats on the website.

Rules for Saving Images:

Save a copy of the original! Make sure you have saved a copy of the original image, so that you can come back and edit it again later if needed. This may be a different format such as, .raw, .tiff, .png, or .psd, or it may simply be the original size of a .jpg (e.g. from your digital camera) It is especially important to save the original if layers have been added to the image or graphic file.
Use JPEG files. Files ending in .jpg are often larger and take longer to load. However, most image editing tools allow you to select the file compression for .jpg. For example, you can choose Maximum, Very High, High, Medium, and Low. Try saving larger images under several compression settings and then test them for quality rendering and load times. Balancing quality, compression, and load times can be a judgment call depending on the particular image and the web document it appears in.
Use web/screen resolution. Final web images should be saved at the same dimensions at the minimum 72 dpi (dots [or pixels] per inch) resolution though you can save the image with up to 150 dpi for the web.
ALT-tags are required! An ALT tag is required for each image. "Alt" text is "alternative" text, e.g. it provides an alternative version of the information available in an image. This text is then included as a part of the code for the image, and can be read by screen reading software.

File sizes:

A file that is too large will take too long to load on the page, and can even be rejected when you try to upload it in Drupal. Choose the optimal file size based on how you are using the image:

For banners or hero images, a file size up to 60KB is acceptable.
For high end photographs, try to keep them to within 100KB at an absolute maximum.

Image size dimensions:

When any image is uploaded, Drupal applies the Focal Point you assign to that image and then crops and scales the image for the area in which it will be used. (Please refer to the Images in Drupal guide article for this in depth).

This means that some images could be used in places that are more horizontal, some more square or vertical, etc.

If we decide to use an image that has a small original size in a Feature Large Flexible Content Item, it may display as very pixelated as Drupal is trying to make a small image fit in a big display element.

With this in mind, it is a good idea to upload images that can work in the following categories.

Image categories:

WYSIWYG Images: 800 x 600px
Squares and Vertical orientation: Thumbnails; Headshots used for Admissions Officer; staff directories; News – Portrait; Social Media Connect; etc. 400px wide, (minimum dimension 350x464px)
Horizontal orientation: Most Flexible Content Items; News – Wide; Hero; etc. 1900×1022 (2:1 aspect ratio)

Previewing an Image in Drupal

Remember, you can see the Preview of all the image sizes and orientations for any image you add to a content item.

Here is an excerpt on the Preview function from our Images in Drupal article

We can click on the Preview link under the thumbnail to see that this focal point we picked really will be the best part of the photo to never get cropped out.

screenshot image preview with focal point

This puts a pop-up window within our pop-up window that displays all the site-wide Image Styles of the image while employing the Focal Point we just selected. We clicked the Focal Point to be on the bike rider in the middle of the path.

screenshot preview image slider

These Image Styles are in a horizontal-scroll pane. If you scroll down you can see the original image for comparison. Here is a view of the horizontal-scroll-pane moved to see the difference between the News/Event Detail Portrait and the News/Event Detail Wide image styles.