Best image format for web, email, print and social

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Most format advice boils down to two questions: what is in the picture, and where is it going? The content decides whether you want lossy or lossless compression. The destination decides how much compatibility you need to protect. This guide takes the content first, then walks through the places an image ends up.

Start with what the picture is

Photographs. MDN calls JPEG "particularly useful for photographs", and web.dev says photos and screenshots can use JPEG, lossy WebP or AVIF, with quality levels tested to balance size against fidelity. Photographs are continuous-tone, so a lossy format can discard detail you will not miss.

Screenshots, diagrams, line art. MDN describes PNG as lossless and better suited to these, and warns that lossy compression on content needing sharpness, such as diagrams or charts, can give unsatisfactory results. In our own measurements (image format file sizes), a synthetic screenshot was smaller as a PNG than as a JPEG at Pillow quality 92 or 80. That is one test image, not a law, but it matches the guidance.

Logos and icons. If you have a vector original, MDN says SVG is ideal for interface elements, icons and diagrams that must be drawn accurately at different sizes, and web.dev says vector formats suit simple shapes like logos. If you only have a raster version, keep it lossless and keep the transparency.

Anything that needs transparency. MDN notes that JPEG does not support an alpha channel, whereas PNG has full alpha transparency. The PNG specification describes an optional alpha channel and lossless, well-compressed storage. Converting a transparent PNG to JPEG replaces the transparent area with a solid colour; ConvertMango's JPG output fills it with white.

Websites

For raster images on a page, MDN's advice is to prefer WebP or AVIF, which generally compress better than PNG, JPEG and GIF, and web.dev says they should be used where possible, with JPEG or PNG as fallbacks. Google's WebP documentation says lossy WebP typically achieves about 30% more compression than JPEG and that lossless WebP files are about 26% smaller than PNG; MDN gives similar ranges. Treat those as averages, since the image matters as much as the format.

Two cautions from MDN. AVIF does not support progressive rendering, so a large file must download fully before it can show. And support for WebP and AVIF is broad but not historic, so MDN recommends a fallback. The usual pattern is a picture element that lists WebP first and JPEG or PNG after it, so older software still gets something.

web.dev also makes a point that is easy to forget: removing an image altogether, or replacing it with CSS, is always the best optimisation, and text is better kept out of images. Smaller image files can reduce transfer time. Loading priority, caching, connection speed and decoding also affect when an image appears.

If a photo on your site is a PNG, PNG to WebP or PNG to JPG will often shrink it a lot; our photo sample dropped from 1.8 MB as PNG to roughly 0.3 MB as JPEG at Pillow quality 92 (a browser encoder will give different sizes). For existing JPEGs, JPG to WebP is the route. One warning on repeat conversion: JPEG is lossy, so converting a JPEG to another lossy format discards a second round of detail. Keep the original.

Email

We could not verify any official table of which image formats each email client renders, so we will not give you one. What is checkable: Gmail's help page says images in messages are shown automatically by default, but users can choose to be asked before external images display, and images in messages Gmail considers suspicious are not shown automatically. So an email should still make sense when pictures do not appear. Put real text in the message body rather than baking it into a banner, and give images alt text.

Beyond that, rely on the general principles above. JPEG is the usual lossy choice for photographs and PNG for graphics. Keep files small, since smaller files can reduce transfer time, including on a slow mobile connection. If a recipient cannot open a WebP image, WebP to JPG converts it in the browser.

Print

Print requirements vary by printer, and we could not source colour-mode or resolution rules from an official page, so we have left them out. What we can cite concerns storage. The Library of Congress describes TIFF as a tag-based format for storing and interchanging raster images, lists it as a preferred format for photographs and other digital graphic images, and notes that it is widely supported by desktop publishing and page layout applications. In its JPEG entry it states a general preference for uncompressed masters of still images, and describes JPEG as acceptable where images exist only in lossy form.

Practical consequence: if you will print an image, work from the largest, least-compressed version you have. Do not take a small JPEG that came from a social post and expect it to print like the camera original. ConvertMango does not make TIFF files, so print-ready work may need desktop software, and your printer's own file guidelines should have the final word.

Social media

Each platform sets its own accepted formats, size limits and recompression behaviour, and these change. We tried the official help pages of several large platforms and could not load their upload specifications, so we are not quoting any numbers or claiming what any specific platform accepts. Check the platform's current guidance before you upload.

One general point from the sources still applies: the quality of what you start with limits what you can end up with, because a lossy file cannot get its detail back. Start from the best version you have. For photographs, JPEG is the usual lossy choice; for graphics and text-heavy images, MDN's guidance favours lossless PNG. If a platform or device refuses a WebP file, WebP to JPG is a quick fix, and WebP to PNG stores the decoded still image without a further lossy encode; it cannot restore detail already lost from the source.

A short decision list

About the tools

ConvertMango's image tools run in your browser, and file contents are not uploaded to ConvertMango's conversion service. Each converts one image at a time, up to 50 MB and 40 megapixels. Where supported, JPEG and lossy WebP exports request browser quality 0.92. PNG export is lossless and does not use that lossy-quality setting. Browser encoders can produce different results. You get five free conversions a day without signing up, and the allowance resets at 00:00 UTC. A conversion only counts when it succeeds. AVIF and HEIC conversion are not offered. For the PNG-or-JPEG decision in more depth, read PNG vs JPG; for the newer format, WebP vs JPEG.

Convert it now

Use our PNG to JPG tool. It runs in your browser, so the contents of your file are not uploaded to our conversion service. You get five free conversions a day without signing up. The allowance resets at 00:00 UTC.

Frequently asked questions

What is the best image format for a website?

For photos, MDN and web.dev point to WebP or AVIF where possible, with JPEG as a fallback. For screenshots and logos, use a lossless format such as PNG or lossless WebP, or SVG for a vector logo.

Should I send photos in email as PNG or JPEG?

For photographs, JPEG is the usual lossy choice and gives much smaller files than PNG. Keep PNG for screenshots and graphics where sharp edges matter.

Is TIFF better than JPEG for print?

TIFF can hold image data without lossy compression, and the Library of Congress lists it as a preferred format for photographs and digital graphic images. Your printer's own file requirements come first, so ask them.

Can ConvertMango make AVIF or HEIC files?

Not yet. Those tools are planned. Today the image tools convert between JPG, PNG and WebP.

Related tools

JPG to WEBPPNG to WEBPWEBP to JPG

More guides

PNG vs JPG: which should you use?WebP vs JPEG: which should you choose?Image format file sizes compared (we measured)

Sources

Plain-text references. Facts that could not be checked against a primary source were left out.

  1. MDN Web Docs, 'Image file type and format guide', https://developer.mozilla.org/en-US/docs/Web/Media/Guides/Formats/Image_types
  2. web.dev, 'Choose the right image format', https://web.dev/articles/choose-the-right-image-format
  3. web.dev, 'Performance issues' (Learn Images), https://web.dev/learn/images/performance-issues
  4. Library of Congress, 'TIFF, Revision 6.0', https://www.loc.gov/preservation/digital/formats/fdd/fdd000022.shtml
  5. Library of Congress, 'JPEG File Interchange Format', https://www.loc.gov/preservation/digital/formats/fdd/fdd000017.shtml
  6. W3C, 'Portable Network Graphics (PNG) Specification (Third Edition)', https://www.w3.org/TR/png-3/
  7. Google, 'Gmail Help: Images in emails', https://support.google.com/mail/answer/145919
  8. Google Developers, 'WebP Frequently Asked Questions', https://developers.google.com/speed/webp/faq
  9. ConvertMango measurement, method in article, 2026-10-26 (see /guides/image-format-file-size-table/)