Optimise Images for Mobile
Mobile-first image budgets, PWA icons, share-ready compression and per-device wallpaper dimensions — every preset a mobile developer or admin needs.
Mobile image optimisation splits into three genuinely different problems. Mobile web (the biggest, and the hardest) — Core Web Vitals treats mobile LCP as a hard ranking signal, and the practical LCP budget on a real 4G connection is around 100–200 KB per above-fold image. App and PWA assets — app icons, favicons, notification banners — each with their own exact-pixel format and resolution rules. And user-generated mobile content — iPhone and Android photos being shared via chat, which start at 4–8 MB straight from the camera and need meaningful compression before send.
This hub covers all three. The mobile-web presets target WebP at 1200–1600 px, quality 78–82, under 200 KB — the reliable CWV-pass ceiling. The app icon presets produce 512 × 512 PNG for PWA manifest and 1024 × 1024 PNG for iOS App Store submission. The sharing presets produce 2400 px JPEG at quality 88–90 — visually identical to the source but a quarter of the file size.
For deeper CWV work (LCP debugging, budget planning), see the /optimise-images-for-seo hub. For website-wide optimisation (heroes, blog inline, product page mains) rather than mobile-specific tuning, see /optimise-images-for-websites.
Mobile web (Core Web Vitals)
Presets tuned for mobile LCP budgets. Under 200 KB WebP at 1400 px is the reliable CWV-pass ceiling for the above-fold hero.
App & PWA icons
Fixed-dimension PNG presets for iOS App Store, PWA manifest, favicons and Android notification banners.
Wallpapers & sharing
Per-device wallpaper dimensions and pre-share compression for photos going through AirDrop, Messages or WhatsApp.
Related tools
Frequently asked questions
- What's the sweet-spot LCP image size for mobile web?
- Under 100–200 KB WebP for the hero. Google's LCP threshold is 2.5 seconds on mobile; on a realistic 4G connection with typical latency, that's roughly the file size that lands in time. Under 100 KB gives comfortable margin.
- Should I upload WebP or JPEG for mobile web?
- WebP. Every mobile browser released since 2020 supports WebP natively (Chrome, Safari, Firefox, Samsung Internet). WebP is 25–35% smaller than JPEG at equivalent quality, which is a meaningful CWV improvement.
- How big should an iOS app icon be?
- iOS App Store submission requires 1024×1024 PNG with no transparency and no rounded corners (iOS masks the corners automatically at render time). The runtime app then uses smaller variants generated from this master.
- Why compress iPhone photos before sharing?
- iPhone 15 Pro photos average 4–8 MB in HEIC format and much larger as full-quality JPEG exports. AirDrop and Messages transfer them uncompressed, which is slow over cellular. Compressing to 2–3 MB before send is visually identical and much faster to deliver.
- Is my image uploaded to a server?
- No. Every preset compresses in your browser using the Canvas API. Files never touch our servers — that's what makes the tool both fast and private.