How to resize and compress product images for a fast store

Phone cameras take very large photos. Uploading them as they are can make your store slow to load, which hurts visitors on mobile data and weaker connections. Resizing and compressing your images fixes this, and it takes only a few minutes.

Two different things: dimensions and file size

Dimensions are the width and height of the image in pixels. File size is how much storage the file uses, measured in kilobytes or megabytes. They are related but not the same. A photo with huge dimensions usually has a large file, but a photo of fixed dimensions can also be saved at different quality levels, producing different file sizes.

To make a store fast you generally want modest dimensions and a moderate file size. A photo displayed in a small card does not need to be thousands of pixels wide, but it should not be so small that it looks blurry on a larger screen or when zoomed in.

Resize first

Reduce the pixel dimensions to a sensible size for the web. Photos shown full-width on a phone and zoomed on a desktop need more pixels than a thumbnail. Many editing apps let you pick a width in pixels when exporting. Pick a size that stays sharp at the largest display you care about, and avoid exporting at full camera size just in case. If you are unsure, check how your store handles uploaded images and view the result on a phone and a desktop.

Upload limits differ between tools and can change, so check yours. If an upload is refused or very slow, a smaller file is the first thing to try.

Then compress

Compression reduces file size by discarding detail the eye is unlikely to notice. Most apps offer a quality setting when exporting. Lower quality means smaller files but more visible artefacts such as blockiness, blur around edges and banding in smooth areas.

• Start with a medium-high quality.
• Zoom in on a detailed area and check for artefacts.
• If it looks fine, try a slightly lower setting and compare.
• Stop when you first see degradation, then go one step back.

Products with fine texture, like fabric weave, need more care than flat colour backgrounds, which compress well.

Choose the right format

The file format also affects size and quality. Photographs usually suit JPEG, while images that need transparency suit PNG, and WebP is a more modern option. See JPEG vs PNG vs WebP for product images for how to choose.

Do it in a batch

If you have many photos, apply the same size and quality to all in one export, as in how to edit a batch of product photos the same way. Keep the full-size originals in a separate folder, so you can export again at a different size later without losing quality, since repeatedly compressing an already compressed file degrades it each time.

Test on a slow connection

Open your store on mobile data, not only on home wifi. If images take a while to appear, shrink them further. Many buyers browse on phones, and speed is part of the impression described in what a website says about a brand before anyone buys.

A good routine

Shoot, edit, resize, compress, then upload. Each product takes seconds once your settings are saved, and your store stays quick as the catalogue grows.