How to Reduce Image File Size Without Ruining Quality

Large images slow down websites, fill up inboxes and get rejected by upload forms. The good news: most photos can lose 50–90% of their size with no visible difference. Work through these steps in order — the first ones save the most.

1. Resize to the size you actually need

Pixel count drives file size more than anything else. A 12-megapixel phone photo is 4000 × 3000 pixels; a blog post rarely displays images wider than 1200 pixels. Halving both dimensions removes 75% of the pixels.

Rules of thumb:

• Websites: the largest width the image is displayed at, times two for high-density (retina) screens — often 1600–2400 pixels for full-width images, less for thumbnails.
• Email and messaging: 1600–2000 pixels on the long side is plenty.
• Printing: width in inches × 300.

Use Resize Image to scale by pixels or percentage; it downsamples in several steps to keep edges sharp.

2. Choose the right format

Content	Best choice
Photos for sharing	JPG
Photos on a website	AVIF or WebP
Logos, screenshots, UI	PNG (with colour reduction) or lossless WebP
Graphics that need transparency on a website	WebP
Simple animations	Animated WebP or video instead of GIF

A screenshot saved as JPEG gets blurry text; a photo saved as PNG can be ten times bigger than necessary. Converting to the right format is often the single biggest win — try PNG to JPG for photos or JPG to WebP for the web.

3. Lower the quality setting — a little

Lossy formats have a quality dial. The relationship between quality and size is not linear: going from 100 to 90 often halves the file, while going from 85 to 80 saves much less. For JPEG, 75–85 is the sweet spot for most photos. For WebP, 75–85. For AVIF, 50–70.

The Image Optimizer automates this: give it a target such as 200 KB and it finds the highest quality that fits.

4. Use a better encoder

Not all encoders are equal. MozJPEG produces standard JPEG files that are typically 5–15% smaller than those from basic encoders at the same visual quality, and OxiPNG shrinks PNG files losslessly by trying many compression strategies. Compress Image uses both.

5. Reduce colours in graphics

Logos, icons and flat illustrations rarely need 16 million colours. Converting a PNG to an optimised palette of up to 256 colours — the technique behind tools like pngquant — often cuts the size by 60–80% while looking identical. Transparency survives. Use Compress PNG.

6. Remove metadata

Phone photos carry EXIF data: camera model, lens, exposure settings, GPS coordinates and sometimes a thumbnail. It is usually 10–60 KB — negligible for a 5 MB original but significant for a 100 KB web image. Removing it also protects your privacy. The metadata remover strips it losslessly from JPG, PNG and WebP.

7. Crop

Everything outside the subject is still pixels you pay for. Crop before you compress.

What not to do

• Don’t re-compress the same JPEG repeatedly. Each save loses a little detail. Keep an original and export once.
• Don’t judge quality at 400% zoom. Look at the image at the size people will see it.
• Don’t upscale. Enlarging a small image adds pixels without adding detail.

A realistic example

A 4032 × 3024 phone photo straight from the camera weighs about 3.5 MB as JPEG. Resized to 2000 pixels wide, re-encoded with MozJPEG at quality 80 and stripped of metadata, it typically lands around 300–450 KB. Converted to AVIF at similar visual quality, it can drop below 200 KB — a reduction of well over 90%.

All the tools linked above run in your browser, so you can experiment freely without uploading anything.