Even the same photo needs a different format and size depending on where it goes. Settings that are perfect for a web page fall short for a print shop, and a size tuned for social media can be overkill for an email attachment. Decide your rules by use case once and you never have to agonize again.
Start with one big principle: JPG for images with smooth, continuous color like photos, and PNG for logos, text, and anything needing transparency. From that baseline, here is the breakdown by situation.
In-article web images
- Format — JPG for photos (quality 75-85%), PNG for logos, icons, and charts
- Width — usually 1200-1600px is plenty for a content column
- File size — aim under 200KB per image for a snappy load
- Prefer WebP/AVIF when you can — 20-50% lighter than JPG at the same quality (supported by most browsers)
Social media (Instagram, X, Facebook)
- Format — mostly JPG; the platform re-compresses anyway, so no need to upload a huge original
- Square posts — 1080x1080px
- Portrait posts and stories — 1080x1350px or 1080x1920px
- Text-heavy cards — re-compression muddies text, so uploading as PNG keeps it crisper
Print and output
- Format — PNG or top-quality JPG, since you want no quality loss
- Resolution — prepare at 300ppi, not the 72ppi used for screens
- Size — pixels = physical print size x 300ppi (e.g. 10cm is about 1181px)
- Color — expect shifts because screens are RGB and print is CMYK
Email attachments and messaging
- Format — JPG for photos you just want to send
- File size — keep each image under 1MB out of courtesy to the recipient
- Size — if it will only be viewed on screen, 1600-2000px on the long edge is enough
- For several images, compress each or bundle them into a single PDF
When to use WebP and AVIF
WebP and AVIF are relatively modern formats that pack the same quality into a much smaller file. They are especially useful when optimizing website speed. But older software and some apps may not open them, so for attachments and sharing where compatibility matters, JPG and PNG are still the safe choice. Think of it as modern formats for display, universal formats for distribution.
In short
To sum up: JPG for photos, PNG when you need sharpness or transparency, WebP/AVIF for web speed, and above all, size the image to its purpose. Using an oversized original as-is is the single most common mistake.
You can convert formats and adjust size and file weight right in Switching's PNG to JPG, JPG to PNG, and image compression tools. Files are processed entirely inside your browser and never uploaded to a server, so you can adapt work documents and personal photos to any use case with peace of mind.