How to Compress a Screenshot for Email, App Store & Slack (2026)
A 14-inch MacBook Pro takes screenshots at 3456 × 2160 pixels. A typical PNG of that screenshot is 4–8 MB. Gmail's attachment limit is 25 MB total, but email providers often strip or reject large inline images. App Store Connect has precise size requirements. Slack compresses images automatically, but large files slow down uploads.
Here's how to get your screenshot to the right size for wherever you're sending it.
Why Are Screenshots So Large?
Modern displays use HiDPI / Retina scaling — typically 2× pixel density. A 1728 × 1080 logical screen takes a 3456 × 2160 screenshot. That's 7.5 million pixels. At 24-bit colour, that's ~21 MB uncompressed. PNG lossless compression gets it to 4–8 MB. Even "small" phone screenshots from an iPhone 15 Pro are 2556 × 1179 at around 2–4 MB.
PNG is lossless, which is why screenshots default to it — but lossless is often overkill for sharing.
Target Sizes by Destination
| Destination | Max size | Recommended format | Recommended dimensions |
|---|---|---|---|
| Email inline image | < 1 MB | JPEG 80% or WebP | 1280 × auto |
| Email attachment | < 5 MB | PNG or JPEG | Original OK if < 5 MB |
| Gmail / Outlook | < 25 MB total | JPEG or WebP | Resize if > 2 MB |
| Slack message | < 1 MB for fast upload | JPEG 85% | 1920 × auto |
| GitHub README | < 1 MB | PNG (lossless) | 1280 px wide max |
| Notion embed | < 5 MB | WebP or JPEG | 1440 × auto |
| App Store — iPhone | < 500 KB each | PNG | See table below |
| App Store — iPad | < 500 KB each | PNG | See table below |
| Twitter / X | < 5 MB | JPEG or PNG | 1200 × 675 |
| LinkedIn post | < 5 MB | JPEG | 1200 × 627 |
| < 16 MB | JPEG | Original usually fine |
App Store Screenshot Requirements
Apple's App Store Connect has exact pixel requirements. Submit the wrong size and your screenshots are rejected.
| Device | Required size | Aspect ratio |
|---|---|---|
| iPhone 6.9" (iPhone 16 Pro Max) | 1320 × 2868 px | 9:19.5 |
| iPhone 6.7" (iPhone 14 Plus, 15 Plus) | 1284 × 2778 px | 9:19.5 |
| iPhone 6.5" (iPhone 11 Pro Max) | 1242 × 2688 px | 9:19.5 |
| iPhone 5.5" (iPhone 8 Plus) | 1242 × 2208 px | 9:16 |
| iPad Pro 13" (6th gen) | 2064 × 2752 px | 3:4 |
| iPad Pro 12.9" (2nd gen) | 2048 × 2732 px | 3:4 |
To resize a screenshot to App Store dimensions:
- Go to screenshot-to.com/screenshot-resize
- Enter the target width (e.g., 1320) — height auto-adjusts with aspect ratio lock off
- Export as PNG
For batch App Store resizing (multiple screenshots for multiple device sizes), use Xcode's screenshot tool or Fastlane's screengrab.
How to Compress a Screenshot for Email
The goal for email is to keep the image under 1 MB while keeping text sharp.
Using screenshot-to.com/screenshot-compress:
- Open screenshot-to.com/screenshot-compress
- Drop your screenshot
- Choose WebP at quality 80 — typically reduces a 5 MB PNG to 200–600 KB
- Or choose JPEG at quality 85 if the recipient might have WebP compatibility issues (rare in 2026 but worth checking for older email clients)
- Click Download
Results to expect:
| Original format | Original size | After WebP 80% | After JPEG 85% |
|---|---|---|---|
| PNG (Retina screenshot) | 5 MB | ~300–600 KB | ~400–700 KB |
| PNG (1080p screenshot) | 2 MB | ~100–250 KB | ~150–300 KB |
| JPEG (phone screenshot) | 2 MB | ~150–300 KB | ~200–400 KB |
How to Resize a Screenshot Before Compressing
If the screenshot is very large (4K, Retina 5K), resize it before compressing — this gives a much smaller output than compression alone.
Using screenshot-to.com/screenshot-resize:
- Open screenshot-to.com/screenshot-resize
- Set the Width to 1280 (good for most sharing purposes)
- Enable Lock aspect ratio (on by default)
- Export as PNG or JPEG
After resizing, compress further with screenshot-compress for the smallest possible file.
Recommended workflow:
- Resize to 1280 px wide → screenshot-resize
- Compress at WebP 80% → screenshot-compress
- Download and attach
This two-step process typically gets a 6 MB Retina screenshot under 150 KB — a 40× reduction with no visible quality loss at normal viewing size.
Format Choice: PNG vs. JPEG vs. WebP
| Format | Best for | Compression | Transparency | Text sharpness |
|---|---|---|---|---|
| PNG | GitHub READMEs, App Store, lossless sharing | Lossless (large files) | Yes | Perfect |
| JPEG | Email, Slack, social media | Lossy (small files) | No | Good at 85%+ |
| WebP | Everything except App Store, email to old clients | Lossy or lossless | Yes | Excellent |
Rule of thumb:
- Sharing in 2026 → WebP
- App Store submission → PNG (required by Apple)
- Maximum compatibility (older email clients) → JPEG
Platform-Specific Tips
Gmail: Paste images inline rather than attaching — Gmail resizes pasted images to ~800 px wide automatically. For attachments, keep under 5 MB per image.
Outlook: Outlook 2016–2019 has WebP rendering issues. Use JPEG for recipients on older Outlook. Outlook 365 and the web app support WebP.
Slack: Slack auto-compresses on upload. For fast uploads, keep under 500 KB. PNG at 1280 px wide is the sweet spot.
GitHub README: GitHub renders images at the container width (~800 px). A 1280 px wide PNG is enough. No need for 2× Retina assets in a README.
Notion: Notion embeds images at display size. WebP at 1440 × auto is the best balance.
Frequently Asked Questions
Will compressing a screenshot make text blurry? JPEG and WebP at quality 80 and above keep text sharp. Below quality 60, you may see compression artefacts around high-contrast edges (like text). For screenshots heavy with text, stay at quality 80 or higher.
What's the difference between compressing and resizing? Compression reduces file size by changing the encoding (lossy/lossless). Resizing reduces the actual pixel dimensions. Both reduce file size. Resizing gives more reduction; compression preserves detail.
How do I compress a screenshot on iPhone without a computer? Open screenshot-to.com/screenshot-compress in Safari on iPhone → tap the share icon on a photo → select the screenshot → the tool processes it locally. No computer required.
Does compressing a screenshot affect OCR accuracy? Yes — heavy compression (quality below 70) can affect OCR accuracy. If you need to extract text from a screenshot AND share it compressed, extract the text first, then compress.
What about PDF compression? screenshot-to.com handles PNG, JPEG, WebP, and BMP. For PDF compression, use Adobe Acrobat, Smallpdf, or iLovePDF.
Related Reading
- How to Blur Part of a Screenshot (Mac, Windows, iPhone, Android)
- Screenshot Converter Online: Text, PDF, JPG & More
Ready to shrink your screenshots? Compress now → · Resize now →