PNG, JPG or WebP: choose the right image format

Match the format to the image

JPG uses lossy compression and is usually effective for photographs, gradients and other continuous-tone images. It does not preserve transparency. Repeatedly opening, editing and saving a JPG can discard more detail, so keep the best original and create distribution copies from it rather than converting the same compressed copy again and again.

PNG uses lossless compression and supports transparency. It is a strong choice for screenshots, diagrams, logos and text with sharp edges, but photographic PNG files can be much larger than equivalent JPG or WebP files. WebP supports lossy and lossless modes plus transparency, making it useful for modern websites when the receiving software supports it.

Convert and inspect the output

Choose one source image and decide where the result will be used. Select JPG for a broadly compatible photograph, PNG for exact pixels or transparency, and WebP when smaller web delivery matters. For JPG or WebP, begin around high quality, download the result and inspect faces, lettering, thin lines and smooth colour transitions at normal size and while zoomed.

Converting to a newer extension does not add missing detail. A blurred or heavily compressed source remains limited, and converting a JPG to PNG only stores the already-compressed pixels losslessly. Compare file size as well as appearance. If the output is larger without looking better or adding transparency, the conversion may not help the intended workflow.

Current format support and web practice

Current browser guidance treats JPEG and PNG as long-established fallbacks and WebP as broadly supported by modern browsers. Newer formats such as AVIF and JPEG XL continue to develop, but compatibility with editing tools, messaging apps and older devices still varies. A website can use the HTML picture element to offer a modern source with a compatible fallback.

SableApps currently focuses on PNG, JPG and WebP because they cover common daily tasks and can be encoded directly by mainstream browser canvas implementations. The converter handles a single still image. Animation, HDR metadata, colour-profile fidelity and complete EXIF preservation are outside its scope, so specialist imaging software remains appropriate for archival or professional colour work.

Protect image quality and private metadata

Browser re-encoding normally creates a new pixel file and may omit camera metadata such as location, capture time or lens details. That can improve privacy, but do not assume every workflow removes every metadata field. Check sensitive outputs with a metadata viewer when location or identity matters, and avoid sharing the source file unnecessarily.

Keep an untouched original until the recipient confirms the converted image works. Test a web image on the actual page and connection, and test a document image after insertion into the final PDF or slide. File size, dimensions and format all affect delivery; the smallest file is not automatically the clearest or most accessible choice.

Worked example: a product photo and instruction screenshot

Suppose a shop has a 4 MB phone photograph and a screenshot containing setup instructions. Convert the photograph to high-quality WebP, compare it with JPG at normal display size and choose the smaller acceptable result. Convert the screenshot to PNG so letters and interface lines remain sharp. Do not force both assets into one format merely for consistency.

Before publishing, check dimensions as well as bytes. A 5,000-pixel image may still be unnecessarily large even after efficient compression, while a tiny image cannot become detailed through conversion. This tool preserves the source dimensions, so resize separately when the destination specifies pixel limits. Finally, load the real page, inspect on a phone and confirm a compatible fallback where the audience includes older software.

Quick checklist

• Use JPG for photographs that do not need transparency.
• Use PNG for screenshots, diagrams and transparent pixels.
• Try WebP for modern web delivery.
• Inspect text, faces and gradients after conversion.
• Keep the original image and verify metadata needs.
• Test the result in the receiving application.

Primary references

Standards and platform support change. Use these authoritative sources to check the current specification and migration guidance.

• MDN — Image file type and format guide
• W3C — Portable Network Graphics specification