Research: What quality fits 500KB?
Method summary: downscale to 1920px longest side, then run binary search to hit ~500KB across varied content types. Record final quality (q) and visible artifacts.
Practical guidance
- Phone photos at 12–48MP: set 1920px first, then target 500KB
- UI/text/screenshots: try PNG or WebP lossless; avoid heavy JPEG
- Portraits/gradients: prefer WebP at 500KB; raise to 800KB if halos appear
Observed ranges
- Photos (1920px): q ≈ 0.55–0.80 to land near 500KB
- Low‑light/noise: q ≈ 0.45–0.70 (try 800KB if banding)
- Flat UI/gradients: switch to WebP lossless or increase target

Example: 4.1MB → 500KB (Saved ~87.8%) at q≈0.62 after resizing to 1920px.
Start here: /compress?kb=500 and toggle WebP/JPEG; preview artifacts before publishing.
All measurements are done locally in browser; no uploads.