How to reduce image size without losing quality

A photo from a modern phone can be 3 to 8 MB. That is far more than a web page, an email or an online form needs. The good news is that most pictures can shrink by 70 to 95 percent while looking almost the same on a screen. This guide explains what makes a file big and how to cut it down in four steps.

What makes an image file big?

Two things decide the size of an image file: how many pixels it has, and how hard those pixels are compressed. A 12 megapixel photo (4000 by 3000 pixels) holds twelve million colored dots. Even with good compression that is a lot of data.

Pixels grow with the square of the width. If you halve both the width and the height, the picture has only a quarter of the pixels, so the file can be roughly four times smaller. That is why resizing is the most powerful step, and why you should always do it first.

Step 1: Resize to the size you really need

Screens are smaller than most people think. A full-screen picture on a laptop needs about 1920 pixels across, a picture in the middle of a web page often needs 800 to 1200, and a thumbnail needs 150 to 300. Sending a 4000 pixel photo to be shown at 800 pixels wastes most of the file.

Websites and blogs: 1200 to 2000 pixels wide.
Email and chat: 1024 to 1600 pixels on the long side.
Instagram and Facebook posts: 1080 pixels wide.
Online forms and ID uploads: whatever the form states, often 200 to 600 pixels.

Step 2: Choose the right format

Photos belong in JPG or WebP. Logos, screenshots and drawings with sharp edges belong in PNG, or WebP when the site supports it. Saving a photo as PNG can make it five to ten times larger than the same photo as JPG, with no visible benefit. Our guide on JPG, PNG and WebP explains the differences in detail.

Step 3: Lower the quality a little

JPG and WebP let you trade quality for size. The relationship is not a straight line: going from 100 to 85 usually removes more than half of the file size and is almost impossible to see, while going from 85 to 40 saves less and starts to show blocky edges and smudged detail.

A quality between 70 and 85 is a good starting point for photos. If you need a file under a fixed size, such as 100 KB, use the file size limit: the tool tries different quality levels and keeps the highest one that fits.

Step 4: Remove hidden data

Photos from phones and cameras carry hidden information called metadata: the camera model, the date, sometimes the exact GPS location. It adds a little to the file size and, more importantly, can reveal where a photo was taken. Saving the picture again with a tool that does not copy metadata removes it. The files made by this site do not contain it.

Mistakes that make pictures worse

Enlarging a small picture. A bigger canvas cannot add detail that was never captured; the result is soft and the file grows.
Saving a JPG again and again. Every save loses a little quality. Keep your original and make a fresh copy each time.
Taking a screenshot of a photo instead of saving it. Screenshots are often larger and less sharp.
Using PNG for photographs. It is lossless, so the file stays large.

A quick recipe

For most photos: resize to the width you need, save as JPG or WebP at a quality of about 80, and check the result at 100 percent zoom. If it still looks good, you are done. If it looks soft, raise the quality a little or make the picture slightly larger.

Frequently asked questions

Does making an image smaller reduce its quality?

Reducing the number of pixels keeps a picture sharp when it is done with a good resizing method, because the detail is simply shown at a smaller size. Lowering the compression quality loses detail, but a small drop is hard to see.

How small can I make a photo?

It depends on the content. A portrait against a plain background can look fine at 30 to 50 KB when it is small. A busy landscape needs far more. Try the file size limit and look at the result.

Is it safe to shrink private photos online?

Here the picture is processed inside your own browser and never uploaded, so it does not leave your device. With other websites, check whether they upload your files.