Quick answer: Resize the image to the largest size it will be displayed at, then compress it to about 70–80% quality and use WebP where possible. This usually cuts file size by 50–80% with no visible loss in quality.
Large images are one of the most common reasons websites load slowly, emails bounce and uploads fail. The fix is simple: compress your images. Done right, you can cut file size by 50–80% without anyone noticing a difference.
Lossy vs lossless compression
Lossy compression (used by JPG and WebP) removes detail the human eye barely notices, giving big savings. Lossless compression (PNG) keeps every pixel but saves less space. For photos, lossy at 60–80% quality is usually the sweet spot.
How to compress an image in 3 steps
- Open the free Image Compressor.
- Drop in your JPG, PNG or WebP image.
- Move the quality slider until you are happy with the size, then click Download.
The tool shows the original size, new size and percentage saved, so you can find the right balance instantly. Everything happens in your browser — your photos are never uploaded.
Resize before you compress
A 4000-pixel-wide photo from your phone is far bigger than any screen needs. Use the Image Resizer to scale it down first. Good sizes to aim for:
- Blog images: 1200–1600 px wide
- Social sharing images: 1200 × 630 px
- Instagram posts: 1080 px wide
- Thumbnails: 300–600 px wide
Choose the right format
- JPG — best for photos.
- PNG — best for logos, screenshots and images that need transparency.
- WebP — modern format that is usually 25–35% smaller than JPG at the same quality, supported by all major browsers.
Switch formats in one click with the Image Converter. It can convert several images at once.
Why image size matters for SEO
Page speed is part of Google’s page experience signals, and images are often the heaviest part of a page. Smaller images mean faster loading, better Core Web Vitals and happier visitors. Combine image optimisation with good on-page SEO for the best results.
Quick checklist
- Resize to the largest size it will actually be displayed at.
- Compress to 60–80% quality.
- Use WebP where you can.
- Give files descriptive names like blue-running-shoes.webp.
- Always add alt text describing the image.
Need to send several photos as one document? Turn them into a single file with JPG to PDF. Explore all free image tools.
Example: getting a photo under 100 KB for a form
Many job, exam and visa forms ask for a photo or scan under a size such as 50 KB, 100 KB or 200 KB. With the Compress Image tool:
Need an exact limit such as 20 KB, 50 KB or 200 KB? Follow our step-by-step guide on how to reduce image size in KB.
- Choose your photo and switch to Target size.
- Enter the limit, for example 100 KB. The tool tries quality levels automatically and, if needed, shrinks the dimensions slightly until the file fits.
- If the form also asks for exact pixel sizes, use Resize Image first, then compress.
- Download and check the size shown before uploading.
Recommended settings by use
- Blog and website images: 1200–1600 px wide, JPG or WebP at quality 75–85.
- Screenshots and graphics with text: PNG or WebP; JPG can blur sharp edges.
- Logos and icons: SVG where possible, otherwise PNG.
- Social media: resize to the platform size first (for example 1080 × 1080 for an Instagram square post), then compress.
Most of the saving usually comes from reducing oversized dimensions. A photo straight from a phone is often 4000 px or more wide, far larger than any screen needs.
Lossy vs lossless compression
Lossy compression (JPG, lossy WebP, AVIF) removes detail the eye barely notices and gives the biggest savings. Lossless compression (PNG, lossless WebP) keeps every pixel exactly but saves less. Compressing a JPG again and again adds more loss each time, so always start from the original file.
Frequently asked questions
Does compressing an image reduce its resolution?
Not necessarily. Changing quality keeps the same pixel dimensions; only resizing changes the resolution. Our tool only reduces dimensions when you set a maximum width or when a target size cannot be reached otherwise.
Why is my PNG larger than the JPG?
PNG is lossless, so photos saved as PNG are usually much larger. Use JPG or WebP for photos and PNG for graphics with sharp edges or transparency.
Is WebP supported everywhere?
All current major browsers support WebP. Some older software and a few upload forms still accept only JPG or PNG, so check the form’s requirements.
Are my images uploaded to your server?
No. Compression happens in your browser, so your photos never leave your device.
Keep reading: related guides
This guide is part of our free image tools collection. Browse all free online tools or the full guide library.