Compress an image to 500 KB
500 KB is a publishing number rather than a form number. Almost nobody is asked for it by an application portal; people arrive at it because they are putting an image on a website and something — a page-speed report, a theme's recommendation, a colleague — told them their images were too heavy. Blog post headers, product pictures, portfolio pieces and CMS media libraries all live around this size.
It is a generous budget by web standards and a tight one by camera standards, which is a comfortable place to be. A full-width hero image can look excellent at 500 KB. The more interesting question at this size is not how to reach it but whether you should be aiming lower, because on a web page the file size is not an upload limit — it is time your visitor spends waiting.
500 KB is a ceiling, not a goal
For a page image, the number that matters is how long the largest visible element takes to appear — the metric Google calls Largest Contentful Paint, and one of the things it measures pages on. A 500 KB hero image on a mobile connection is a meaningful fraction of that budget all by itself, and it is usually the single largest thing on the page.
So treat 500 KB as the point beyond which an image is definitely too heavy, and then see how much lower you can go before it starts to show. Most pictures on most pages are fine at 150–250 KB. Run one at 500 KB, then run the same picture at 200 KB and look at them side by side at the size they will actually be displayed. The difference is frequently invisible and the saving is not.
Size the image to how it is displayed, too. A picture rendered 800 pixels wide in a blog layout does not need to be a 3000-pixel file, and downscaling it first will do more for the file size than any amount of quality tuning.
Use WebP if you are publishing
This is the one context where the format choice is straightforward. WebP is typically 25–35% smaller than a JPG that looks the same, it keeps transparency where JPG cannot, and every browser in current use displays it. On a web page there is no compatibility argument left.
Practically, that means a WebP at 350 KB looks like a JPG at 500 KB. Convert first, then set the target — you get the better image and the lighter page at once.
Keep the JPG or the original somewhere. WebP is the right delivery format and a poor archive format, and you will want the full-quality file the next time the design changes.
Screenshots, diagrams and logos are a different problem
A picture belongs in JPG or WebP. A screenshot, a chart, a diagram or a logo is flat colour with hard edges, and JPEG puts visible fuzz on exactly those edges — the text in a screenshot compressed as JPEG looks noticeably worse than the same screenshot as PNG, at a larger file size.
For those, keep PNG and optimise it losslessly, or use WebP, which handles both kinds of image well. Image KB Reducer compresses PNGs by optimising and quantising rather than by turning down a quality dial, because PNG has no quality dial to turn.
Questions about 500 KB
Is 500 KB good enough for a website image?
It is acceptable and rarely optimal. 500 KB is a fine upper bound for a large hero image; for anything smaller on the page, aim considerably lower. The honest test is to compress the same picture to 500 KB and to 200 KB and compare them at the size they will actually be displayed — most of the time you will not be able to tell.
Does compressing images improve my Core Web Vitals?
It directly affects Largest Contentful Paint, which is usually an image on a content page. Smaller image, earlier paint. It does not affect layout shift or interaction latency, which are separate problems with separate causes — set explicit width and height attributes for the first of those.
Should I convert to WebP before or after compressing?
Convert first, then set the byte target on the WebP. Compressing a JPG to 500 KB and then converting it to WebP means you paid JPEG's compression damage and WebP's, and got the worse image of the two paths.
Why is my PNG still large after compressing to 500 KB?
If it came out under 500 KB, it worked. If it did not, it is because PNG is lossless and there is no quality setting to lower — Image KB Reducer optimises and quantises, then reduces dimensions, and for a picture saved as PNG that is not always enough. Converting a picture from PNG to JPG or WebP will get you far below 500 KB with no visible loss.
Tools that help at this size
- Image to WebP
The right delivery format for anything going on a web page. Same look, roughly a third less weight.
- Image Resizer
Size the image to how it is actually displayed. Worth more than any quality setting.
- PNG to JPG
A picture saved as PNG is the usual reason a page image is enormous.
Other exact sizes
Each of these is a different page about a different size, because different things ask for them. If none of them is your number, set any target you like.