How to Reduce Photo File Size Without Losing Quality
A phone photo is 3–5 MB; most uses need a tenth of that or less. The good news: the vast majority of those bytes are invisible — resolution no screen will show and quality margins no eye can see. Reducing file size well is a three-step process, in a specific order.
Privacy-first: every image is processed locally in your browser. Nothing is uploaded, stored or transmitted to any server.
Why photos are so large to begin with
Modern phones shoot 12–48 megapixels at conservative quality settings — dimensions meant for large prints and heavy cropping, not for a 1200-pixel-wide web view or a chat message. A 4000×3000 photo displayed at 800×600 wastes 96% of its pixels; they cost bytes while contributing nothing you can see.
Step 1: resize to the dimensions you actually need
Resizing is the biggest lever. Halving width and height quarters the pixel count and typically cuts file size 70–80% before compression even enters the picture. For web and social, 1080–1600px on the long edge covers almost everything; for email, 1200px is plenty. Use high-quality stepped downscaling (what PixelVault’s resizer does) so the smaller image stays crisp.
Step 2: compress with intent
JPG and WebP quality settings are logarithmic in practice: dropping from 100 to 80 halves the file with virtually no visible change, while 80 to 60 saves less and starts to show. Compress with a live before/after comparison so you judge with your eyes, or — when a form demands “under 200 KB” — use a target-size mode that finds the best quality fitting the cap automatically.
Step 3: let the format help
The same photo at the same visual quality: PNG is largest by far, JPG the baseline, WebP ~30% smaller, AVIF smaller still. If the destination is a website, converting to WebP during compression is free savings. If a photo is stuck as a PNG or BMP, converting to JPG alone can shrink it 10×.
What not to do
Don’t re-compress an already-compressed JPG repeatedly — each generation degrades it; work from the original when possible and keep it. Don’t ZIP photos hoping for savings; JPGs are already compressed and ZIP achieves ~nothing. And don’t upscale a small image to “improve” it before compressing — you pay bytes for invented pixels.