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How to reduce image size without losing quality

Updated

"Without losing quality" is not quite achievable in the literal sense — every lossy compression discards something. What is achievable, and what people actually mean, is losing nothing you can see at the size the image will be viewed.

The trick is the order of operations. Most people reach straight for a quality slider, which is the least effective lever and the most damaging. Cropping and resizing first removes far more bytes for zero visible cost, leaving compression with an easy job instead of an impossible one.

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Step by step

  1. Crop away anything you do not need

    This is free. Pixels you remove cost nothing and improve the composition. On a photographed document, cropping the surrounding desk can halve the file before anything else happens.

  2. Resize to the dimensions it will actually be displayed at

    This is the big one. An image shown 800px wide on a page gains nothing from being 4000px wide — but it costs 25 times the pixels. Halving both dimensions removes 75% of the data with no visible change at display size.

  3. Only then apply compression

    With sensible dimensions, quality 80–85 is visually identical to the original for photographs. It is only when dimensions are far too large that the encoder is forced into visible artefacts.

  4. Choose the right format

    WebP typically produces files 25–35% smaller than JPEG at matching quality, and supports transparency. Use JPEG for maximum compatibility, PNG only for screenshots and line art.

Things worth knowing

  • Enlarging cannot add detail. Upscaling a small image interpolates from neighbouring pixels and always looks softer than a photograph genuinely captured at that size.
  • Re-compressing an already-compressed JPEG stacks artefacts. Always work from the original.
  • Screenshots and diagrams belong in PNG or WebP. JPEG puts visible halos around sharp text edges.
  • Re-encoding strips EXIF, which removes GPS coordinates — useful before sharing photos publicly.

Frequently Asked Questions

What is the difference between resizing and compressing?

Resizing changes how many pixels the image has. Compressing changes how efficiently those pixels are stored. Resizing is the far bigger lever and, done to the display size, is effectively free in visual terms. Compression is what you apply afterwards to finish the job.

Is WebP safe to use now?

Yes. Every current browser supports it, and it gives meaningfully smaller files than JPEG at equal quality with transparency support as a bonus. The main caveat is older software and some upload portals that only accept JPEG or PNG.

What quality setting should I use?

80–85 for photographs is the standard sweet spot — visually indistinguishable from the original at normal viewing size. Below about 60, blocking artefacts appear around edges and in flat gradients like sky.