Free image resizer · Browser only · No upload
Resize an image for social media in your browser.
Poster Poster Resize is a free in-browser image resizer with 13 social media presets. No upload, no signup, no watermark.
Instagram square, story, reel. TikTok thumbnail. YouTube thumbnail. Facebook cover. Pick a preset, drop your image, download the resized version. Nothing uploads — it all happens in your browser.
Target: 1080 × 1080px
Often used together
All four tools are free, browser-only, no signup required.
Compress for upload limits
Resizing alone won't always hit a 500KB target. Compress to fit Reddit, web forms, or email caps.
📄Combine into a PDF
Drop multiple resized images into one PDF — handy for expense reports, application packs, or proofs.
🎨Design a poster on top
Add text, logos, and brand colours over your resized image. Same browser-only, no-signup model.
Common social media image sizes (2026)
Platforms tweak dimensions every couple of years and most online cheat sheets are out of date by the time you find them. The presets in the tool above match what each platform's current upload spec accepts as of 2026. Quick reference table:
| Platform | Use case | Pixels | Aspect |
|---|---|---|---|
| Square post | 1080 × 1080 | 1:1 | |
| Portrait post / Reel | 1080 × 1350 | 4:5 | |
| Story | 1080 × 1920 | 9:16 | |
| TikTok | Vertical video / thumbnail | 1080 × 1920 | 9:16 |
| YouTube | Video thumbnail | 1280 × 720 | 16:9 |
| YouTube | Shorts thumb | 1080 × 1920 | 9:16 |
| Square post | 1200 × 1200 | 1:1 | |
| Cover photo | 820 × 312 | ~21:8 | |
| X (Twitter) | In-feed post | 1200 × 675 | 16:9 |
| X (Twitter) | Header banner | 1500 × 500 | 3:1 |
| Single post | 1200 × 627 | ~1.91:1 | |
| Cover photo | 1584 × 396 | 4:1 | |
| Standard pin | 1000 × 1500 | 2:3 |
Why does the resize happen in your browser?
Most free online image resizers upload your image to a server somewhere, process it there, and email the link or hand it back as a download. That works, but it's slow over a phone connection and the privacy story is murky — your photo lives on someone else's server until they decide to delete it.
This tool runs entirely in your browser. We send your image to a canvas element, resize it via the browser's built-in graphics APIs, and hand the resized version back to you as a download. Nothing leaves your device. Nothing gets uploaded to us. It works offline once the page has loaded.
Crop to fit, fit with padding, or stretch?
When you resize an image to a different aspect ratio (a tall portrait into a square Instagram post, say), there are three ways to handle the mismatch:
- Crop to fit (default)— fills the target frame completely by cropping the parts of the image that don't fit. Best for most social posts where the subject is centred.
- Fit with padding— scales the entire image to fit, then adds blank padding bars to fill the rest of the frame. Best when you don't want any of the original cropped out (e.g. a poster with text near the edges).
- Stretch— distorts the image to match the target shape exactly. Almost always wrong, but occasionally useful when you don't care about aspect ratio.
From single resize to automatic posting
If you find yourself resizing the same kind of image every week — an event flyer for Instagram, a TikTok thumbnail, a Facebook cover update — the underlying problem is repetition. Resizing one image takes 30 seconds. Doing it weekly across five platforms is a silent hour of your week.
Poster Poster handles that same job automatically. Connect your Google Calendar, drop in your brand template, and we generate every required image size and post each one to the right platform on schedule. Free resize tool stays free; Poster Poster is for when the resize is just one step in a recurring posting workflow you'd rather not run by hand.