What resolution means
A wallpaper's resolution is its width × height in pixels. Your screen has a fixed grid — an iPhone 16 Pro is 1206 × 2622 — so an image at exactly that size maps one pixel to one pixel: maximum sharpness, no scaling. Anything smaller gets stretched and looks soft; anything larger is simply shrunk (fine, just a bigger file).
iPhone
iPhone 16 Pro Max 1320 × 2868 · iPhone 16 Pro 1206 × 2622 · iPhone 16 / 15 / 14 Pro 1179 × 2556 · iPhone 14 / 13 / 12 1170 × 2532 · iPhone 13 mini 1080 × 2340 · iPhone SE 750 × 1334.
Samsung & Pixel
Galaxy S24 Ultra 1440 × 3120 · Galaxy S24 / S23 1080 × 2340 · most Galaxy A / M 1080 × 2400 · Pixel 8 Pro 1344 × 2992 · Pixel 8 / 7 1080 × 2400. Many Android phones scroll the wallpaper for a parallax effect, so a full-height image like 1080 × 2400 is the safe choice.
iPad & desktop
iPad Pro 13" 2064 × 2752 · iPad Air / 11" 1640 × 2360 · iPad 10.9" 1640 × 2360. Desktop: 1920 × 1080 (1080p) · 2560 × 1440 (1440p) · 3840 × 2160 (4K).
The one-tap way
You don't have to memorize any of this. Open any PicLoy wallpaper, tap "Edit & crop", and choose your exact model under "Fit my device". The download is produced at precisely that pixel size, cropped from the center — a perfect fit with no guesswork.