Square product images and social media content do not always need to be at the most commonly cited dimensions. 840x840 sits in a useful middle range that is larger than the basic 600x600 product thumbnail size but smaller than the full 1000x1000 that activates zoom features on major marketplaces. Some ecommerce themes and social media scheduling tools use 840x840 as a preset for square content, and certain print on demand platforms list this as an accepted size for square product designs. When a workflow or a theme specifically outputs or expects this dimension, having a reliable way to match it exactly saves time.
How to Resize an Image to 840x840
Enter 840 in both the width and height fields. Turn the Maintain Aspect Ratio checkbox off before processing for a forced square output. With it on and a non-square original, one side reaches 840 while the other follows the original proportions, so the output will not be an equal square.
For product images and social content where the subject needs to stay centered, preparing the image as a square before uploading gives a cleaner result. For a full batch of images, upload everything at once and download as a ZIP when processing is done.
Common Uses for 840x840 Images
Ecommerce product images in themes and platforms that use this as a default square thumbnail size benefit from having source images at exactly 840x840. Shopify themes with built-in image size configurations and WooCommerce setups with custom thumbnail sizes sometimes land on this dimension for their medium product image display.
Square social media posts prepared slightly above standard display resolution also use this size. The extra pixels give platform compression algorithms more to work with, which can result in slightly sharper displayed images compared to uploading at the minimum accepted size.
Output Format at This Size
JPEG works well for product photography and social media photos at 840x840. File sizes stay manageable and quality holds up for photographic content at this resolution. PNG is the right pick for images with transparent backgrounds, graphic content with text overlays or anything where clean edge rendering matters more than keeping the file small. WEBP is a good option for web store product images where faster loading is a priority.