Aspect ratio
An aspect ratio is the shape of an image, given as its width compared with its height: 1:1 is square, while 4:3 and 16:9 are wider than tall.
- Height-to-width ratio
What it means
Two pictures can differ hugely in size and share a shape. A photo 500 by 500 pixels and one 2048 by 2048 are both square, a ratio of 1:1. One 1600 by 1200 is 4:3, and one 1920 by 1080 is 16:9.
Platforms ask for particular shapes. For product markup on a web page, Google recommends several high-resolution images in the ratios “16x9, 4x3, and 1x1”.1 Shopify says main images shown side by side on collection pages only display at the same size with “a consistent aspect ratio”. For a square image, it says 2048 by 2048 “usually displays best”.2
Changing a shape means cropping, which cuts part of the picture away, or padding, which adds plain space around it. Google may also crop a product image itself: it “may test subtle cropping on your image to better frame the item and highlight key product details for shoppers”.3
Think of it like this
A picture frame has a shape as well as a size. A frame made for a 4:3 photo will not take a square one without cutting the photo down or leaving a gap.
For example
A supplier sends one product shot 1600 by 1200 (4:3) and the next 1000 by 1500 (2:3, taller than wide). On a category page they sit at different heights. Padded onto white squares of 1600 by 1600 and 1500 by 1500, both become 1:1 without losing anything.
Why it matters
Mixed shapes make a category page look uneven, and settling the shape before a thousand files are converted is easier than after. Pad with care: Google’s best practice is for the product to take up “no less than 75%” of a product image.3
Not to be confused with
Aspect ratio says nothing about size. Pictures of 500 by 500 and 2048 by 2048 are both 1:1, but the second holds nearly 17 times as many pixels.
Sources
- Google Search Central. Merchant listing (Product, Offer) structured data.
- Shopify Help Center. Product media types.
- Google Merchant Center Help. Image link [image_link].