How to compress an image
Add your images by dragging them onto the box or clicking to browse. A whole folder at once is fine.
Choose the output format next. Auto keeps whatever the file already was. JPG is the safe universal choice. WebP is smaller than JPG at the same quality. PNG stays lossless, which you want for logos and screenshots.
Then set the quality slider and, if the photos are large, cap the width. Press compress and you will see the before and after size on each file.
Resize first, compress second
Most people reach straight for the quality slider. The bigger win is usually the width cap sitting right next to it, and the reason is arithmetic.
Pixel count scales with area, not with width. Halve the width of an image and you quarter its pixels. Take a 4000 pixel wide photo down to 800 pixels and you have cut it to one twenty-fifth of the original pixel count, because 4000 divided by 800 is 5, and 5 squared is 25.
Now think about where that photo is going. A full-width image on a phone screen is displayed at around 400 to 800 pixels wide. Uploading a 4000 pixel photo to sit in that slot means roughly 96% of the pixels you sent get thrown away by the browser before anyone sees anything.
So the order that works: cap the width to what the image will actually be displayed at, then compress. Quality-slider compression alone on an oversized image is squeezing a file that should not have been that big to begin with.
The exception is anything destined for print, or an image people are meant to zoom into. Keep those large.
Which format to pick
Google's own WebP compression study puts WebP files 25 to 34 percent smaller than JPEG at matched visual quality. AVIF goes further again, landing around half the size of JPEG and 20 to 30 percent under WebP.
To put real numbers on it, a product photo that runs 180 KB as a JPEG typically comes in near 110 KB as WebP and around 75 KB as AVIF, all looking the same to the eye.
| Format | Type | Best for |
|---|---|---|
| JPG | Lossy | Photos, maximum compatibility |
| WebP | Lossy or lossless | Photos on the web, smaller than JPG |
| PNG | Lossless | Logos, screenshots, transparency |
JPG remains the answer whenever a file has to open absolutely anywhere, including old software and printers. WebP is the better default for anything living on a website.
Stop saving photos as PNG
This is the single most common reason an image is enormous for no reason.
PNG is lossless. It stores every pixel exactly, which is exactly right for a logo with flat colour, a screenshot of text, or anything needing transparency. Feed it a photograph, with its millions of subtly different colours and its noise, and PNG has nothing repetitive to work with. It stores all of it faithfully and the file balloons.
A photo saved as PNG can easily run five to ten times the size of the same photo as a JPG that nobody could tell apart. If your screenshot contains a photograph rather than an interface, it belongs in JPG or WebP.
Screenshots of actual interfaces, with their flat panels and crisp text, are the opposite case. Those compress beautifully as PNG and look mushy as JPG.
What the quality slider is doing
Lossy compression throws away detail your eye is bad at noticing. Colour detail goes first. Brightness detail is protected longer, because human vision is far more sensitive to light than to hue.
The useful range is 75 to 85. Under 70, you start to see it. Smooth areas like skies and skin go blotchy first, then coloured fringing creeps in around hard edges and text. Over 90 and you are paying kilobytes for detail nobody can perceive.
Here is the part that bites. Every lossy save is permanent. Compress an already-compressed JPG, save it again, and the losses stack. Raising the quality slider later gets none of it back, because the detail is gone, not hidden. Always work from the best original you have.
Why smaller images matter
Images are the heaviest thing on most web pages, and they are usually the element that Google's Largest Contentful Paint measurement times. That metric wants your main content visible within 2.5 seconds.
There is a plainer reason too. Email attachments and upload forms cap out, often at 5 MB or 10 MB, and a handful of modern phone photos blows through that instantly. Compressing gets you under the line without cropping anything or dropping images from the set.
Frequently asked questions
What quality setting should I use?
Start at 80. Drop toward 75 if the file still needs to be smaller, and only go under 70 if size matters more than appearance. Push above 90 and you are paying in kilobytes for detail nobody perceives.
Will compressing the same image twice make it worse?
Yes, for JPG and WebP. Lossy compression is not reversible, so each round removes more detail permanently. Work from the original file every time.
Which format gives the smallest file?
AVIF, then WebP, then JPG. AVIF is roughly half the size of JPG at the same perceived quality, and WebP sits 25 to 34 percent under JPG.
Why is my PNG still huge after compressing?
PNG is lossless, so the quality slider has far less to work with. If the image is a photograph, convert it to JPG or WebP instead. Keep PNG for graphics and transparency.
Can I compress a batch at once?
Yes. Add as many as you like, set the options once, and download the results individually or as a single ZIP.
Does resizing hurt quality?
Making an image smaller does not, since you are discarding pixels that were never going to be displayed. Scaling one up does, because the missing detail has to be invented.
Related: resize before compressing · convert iPhone HEIC photos · change format · crop first.