File size predicts download time. Dimensions predict RAM.

React Native Image Memory Calculator

A 120 KB WebP and a 2 MB JPEG of the same dimensions cost exactly the same decoded RAM. Paste a URL, get the gap between what it costs and what it should cost.

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Understand the numbers

How image memory actually behaves in React Native. Expand any section.

decodedBytes = width × height × bytesPerPixel — 4 bytes/pixel for ARGB_8888. File size never appears in that formula.

Dimensions	Decoded RAM
360 × 360	506.25 KB
720 × 720	1.98 MB
1080 × 1080	4.45 MB
1250 × 1250	5.96 MB
1080 × 1920	7.91 MB
4096 × 4096	64.00 MB

Serve display-appropriate URLs from the CDN. ?w=360 for a grid cell, ?w=1080 for a hero. Biggest win, zero app risk, works with every image library.
One image library, not two. Eliminates duplicate memory caches competing for the same RAM budget.
Pin the memory cache size. Set an explicit byte budget instead of accepting a percentage-of-RAM default.
Deferred/visibility-aware loading. Where the library offers it, so offscreen list items release their bitmaps.
Explicit recycling key in recycled lists. Avoids showing a stale image and holding two bitmaps during the swap.
RGB_565 for opaque thumbnails. Halves memory, costs colour banding. Not for product photography.
WebP / AVIF. Real bandwidth win, zero memory win. Listed last deliberately.