The Facebook Marketplace Listing Image size (1200×1200px)
Facebook Marketplace displays listing photos as squares in its browse grid, so a 1:1 image at 1200x1200 pixels fills the frame cleanly and avoids the top-and-bottom cropping that trims tall or wide photos. At this resolution your item stays crisp on both the mobile app, where most Marketplace browsing happens, and on desktop, without forcing Facebook to heavily recompress an oversized file.
The first photo is what stops the scroll. Marketplace buyers skim dozens of square thumbnails at a glance, so a bright, well-framed 1200x1200 hero image with the item centered and filling the frame reads far better than a distant or cluttered shot. Because the grid crops to a square, anything important placed near the edges risks being cut in the thumbnail even if it shows in the full listing, so keep the subject centered with a little breathing room.
You can add multiple photos to a listing to show condition, angles, and any flaws, which builds buyer trust in local secondhand sales, and keeping them all at 1200x1200 makes the set look consistent. This size is a sweet spot: large enough to look sharp when a buyer taps in, small enough to upload fast over mobile data. Everything here resizes 100% in your browser with no upload and for free, so your photos never leave your phone or laptop. Facebook adjusts Marketplace display and image handling over time, so verify the current behavior before listing.