Threads Image Dimensions
The recommended Threads post size is 1080 × 1350 pixels at a 4:5 aspect ratio. This is the same portrait frame used on the Instagram feed, Meta unified the two so cross-posting works without cropping.
4:5 portrait fills the most vertical space in the Threads feed, pushing competing posts below the fold. That extra real estate translates directly to more attention before users scroll past.
Supported aspect ratios
| Ratio | Pixel Size | Use Case |
|---|---|---|
| 4:5 (portrait) | 1080 × 1350 px | Default, maximum feed presence |
| 1:1 (square) | 1080 × 1080 px | Cross-posting from Instagram grid |
| 1.91:1 (horizontal) | 1080 × 566 px | Wide product shots, screenshots, quotes |
Anything outside these ratios is cropped to the nearest supported ratio. If your image is taller than 4:5 (say 9:16), Threads crops the top and bottom, important content in those areas will disappear.
Carousel Posts
Threads allows up to 10 images per post in a swipeable carousel. A few rules worth knowing:
- All images in a carousel use the aspect ratio of the first image. Plan the lead frame at 4:5 and the rest will follow.
- If you mix portrait and square images, the square ones get padded with white space.
- Carousels show a small dot indicator at the bottom, leave a margin of ~80 px so it doesn't overlap your visuals.
File Format & Size Limits
- File format: JPG (recommended for photos), PNG (for graphics with text or sharp edges)
- Max file size: 8 MB per image
- Color mode: sRGB, uploading Adobe RGB or CMYK shifts colors after Threads converts them
- Min resolution: 320 px wide (anything smaller gets rejected)
- Animated GIF: Supported, auto-plays in feed, 8 MB limit
Why Images Look Compressed
Threads re-encodes every upload server-side to keep mobile data usage manageable. To preserve quality:
- Upload at exactly 1080 px wide, uploading 2160 or 4K just downsamples and adds artifacts
- Export JPG at 80–90% quality, lower introduces banding, higher gets re-compressed anyway
- Use sRGB not Adobe RGB, Threads strips ICC profiles and reinterprets colors
- Skip aggressive sharpening, Threads' encoder amplifies sharpening halos
If precise sizing matters, use our Instagram Photo Resizer, same ratios as Threads, to export at exactly 1080 × 1350.
Caption & Alt Text
- Caption: 500 characters max
- Alt text: Up to 1,000 characters per image, set during upload
- Hashtags: One hashtag per post (Threads only allows one), choose deliberately
- Mentions: Standard @ syntax, autocompletes from your follow list
Tips for High-Quality Threads Posts
- Default to 4:5 portrait for maximum feed presence
- Match aspect ratios across a carousel's images
- Export at exactly 1080 px wide in sRGB JPG at 80–90% quality
- Place key elements in the center, carousel dots and UI overlays sit at the bottom
- Cross-post Instagram feed posts unchanged, same dimensions, no resize needed
- Write alt text for accessibility, Threads supports up to 1,000 characters
Frequently Asked Questions
What is the best image size for a Threads post?
The best size for a Threads post is 1080 × 1350 pixels at a 4:5 portrait aspect ratio. This fills the most vertical real estate in the feed without being cropped, which gives your post the strongest visual presence.
What aspect ratios does Threads support?
Threads supports 4:5 (portrait, 1080 × 1350), 1:1 (square, 1080 × 1080), and 1.91:1 (horizontal, 1080 × 566). Anything outside these ratios gets cropped to fit. 4:5 takes the most space in the feed and is generally the strongest default.
What is the maximum file size for a Threads image?
Threads accepts images up to 8 MB. For best quality, export JPG at 80–90% quality or use PNG for graphics with sharp edges and text.
How many images can I post on Threads?
You can attach up to 10 images per Threads post in a carousel. Each image obeys the same size and file limits, keep all images at the same aspect ratio so the carousel displays cleanly without letterboxing.
Does Threads support GIFs?
Yes. Threads supports animated GIFs and they auto-play in the feed. Keep GIFs short (under 5 seconds) and under 8 MB so they upload reliably and play smoothly on slower connections.
Why do my Threads images look compressed?
Threads re-encodes uploads to optimize for mobile. Always upload at exactly 1080 px wide, use sRGB color, and export JPG at 80–90% quality. Uploading larger files (e.g. 4K) doesn't help, Threads downsamples them anyway and quality often drops.
Are Threads and Instagram post sizes the same?
Yes, Threads inherited Instagram's 4:5 (1080 × 1350) feed format. If you have an Instagram feed image ready, you can post it on Threads at the same size with no changes.
What should the alt text on a Threads image look like?
Threads supports up to 1,000 characters of alt text per image. Describe what's visible in the photo factually, start with the subject, mention key context, and avoid keyword stuffing. Alt text helps screen readers and may help discoverability.