Compress Images for Instagram — Free, Fast & Private
Every photo you post goes through Instagram's own encoder, and it is not gentle: anything wider than 1080px is downscaled, then the result is re-compressed to a few hundred kilobytes whatever you uploaded. Give it a 12-megapixel camera file and it makes all of those decisions for you, quickly and badly — that is the soft, blotchy version of your photo that shows up in the feed. Resize to 1080 × 1350 (or 1080 × 1080 for a square) and get the file under 1MB first, and the re-encode has almost nothing left to throw away.
MiniPx does that resize and compress entirely in your browser — nothing is uploaded to a server, and your photo stays on your phone or laptop from start to finish.
Instagram image dimensions guide
| Image type | Dimensions | Aspect ratio | Max size |
|---|---|---|---|
| Square post | 1080 x 1080px | 1:1 | Not published |
| Portrait post | 1080 x 1350px | 4:5 | Not published |
| Landscape post | 1080 x 566px | 1.91:1 | Not published |
| Story | 1080 x 1920px | 9:16 | Not published |
| Profile photo | 320 x 320px | 1:1 | Not published |
Portrait posts take up the most screen space in the feed, which means more attention on your content — and the tallest supported shape is now 3:4 (1080x1440), which also matches the profile grid's portrait tiles; the Instagram post size guide compares it against the classic 4:5 (1080x1350). If you're choosing between square and portrait, go portrait. For broader social media tips, see compress images for social media.
Why compress before uploading to Instagram?
Instagram does not publish a file-size cap for photos in its Help Center, and whatever you upload is re-encoded. When you start with a bloated file, Instagram's algorithm makes more aggressive decisions about what to throw away. Starting with a clean, pre-compressed file around 500KB-1MB means Instagram applies less additional compression.
Reels cover images
Instagram recommends 420 x 654 pixels (a 1:1.55 ratio) for a reel cover photo. A good cover image should be under 1MB and in JPEG format. Use MiniPx to compress your cover, then upload it when publishing your reel. Keep text within the centre area — the top and bottom get clipped in the grid view.