What is aspect ratio?
Definition
Aspect ratio is the proportion of an image's width to its height, written as two numbers such as 1:1, 4:5 or 16:9. It describes the shape of the image, not its size. A 1000 by 1000 photo and a 2000 by 2000 photo share the same 1:1 ratio.
Why it matters for sellers
Product grids and listing pages are built around a fixed shape. If your photo has a different ratio, the platform may crop it, add empty bars, or squeeze it. Choosing the right ratio before you upload keeps the product centered and fully visible.
Keeping one ratio across a catalog makes a store look consistent. It also makes later changes easier, because photos that share a shape can be resized to any new target size without recomposing each one.
How to do it with Instasize
Instasize lets you pick a preset with the ratio you need, or enter custom pixel dimensions, then shows a preview before you download.
- Open the Image Resizer and add your photo.
- Pick a marketplace or social preset, or enter a custom width and height.
- Look at the preview to confirm the product is not cut off.
- Download the image.
Related Instasize pages
Examples
Square versus portrait
A dress photographed as a tall portrait does not fit a 1:1 grid. The seller crops or extends the canvas to a square so the full garment shows.
Stretched logo
Forcing a wide image into a square box without keeping the ratio makes round objects look oval. Locking the ratio avoids this.
Same ratio, different size
A 1200 by 1200 photo and a 2400 by 2400 photo are both 1:1. Either can be resized down to a smaller square without changing its shape.
Frequently asked questions
How do I calculate aspect ratio?
Divide the width and the height by their greatest common divisor. A 1600 by 1200 image reduces to 4:3. The Image Dimensions Checker reports it for you.
Is aspect ratio the same as size?
No. Aspect ratio is the shape. Size is the pixel count. Two images can be very different sizes and still have the same ratio.
What happens if my photo does not match the required ratio?
The platform may crop it, add padding, or reject it. It is safer to crop or resize to the right ratio yourself and check the preview.
Can I change the ratio without cutting off my product?
Yes. Crop with the product centered, or extend the canvas so the photo has more background. Check the marketplace's current image policy for its rules.