How to compress an image to 100KB (without it looking terrible)
100 KB is the most common upload limit on the web. Here is what actually gets you there, in what order, and where the quality really goes.
By Ranjith R, Creator & Developer of TryImagerPublished Last updated: 6 min read
A photo straight off a modern phone is somewhere between 2 and 6 MB. Getting it to 100 KB means removing over 95% of the file. That sounds brutal, and it would be if compression were the only lever — but most of that 95% is resolution you were never going to see on the screen the image ends up on.
Do it in this order
- Crop away anything that isn't the subject. Pixels you delete cost nothing to store.
- Resize to the dimensions the destination actually displays. Halving width and height removes about three quarters of the pixels.
- Choose the format: JPG for photographs, WEBP if the destination accepts it, PNG only if you need transparency.
- Only now lower the quality, and stop as soon as you are under the limit.
What dimensions get you to 100 KB
| Image width | Typical JPG size at quality 80 | Comfortably under 100 KB? |
|---|---|---|
| 3000 px (unresized phone photo) | 700 KB – 1.5 MB | No |
| 1600 px | 200 – 400 KB | Only with lower quality |
| 1200 px | 100 – 220 KB | Usually, with a small quality drop |
| 800 px | 40 – 110 KB | Yes |
| 600 px | 20 – 60 KB | Comfortably |
These are ranges, not promises — a busy photo of foliage compresses far worse than a portrait against a plain wall, because compression exploits similarity between neighbouring pixels and leaves are relentlessly detailed.
Format changes the maths
PNG is lossless. It has no quality dial, so you cannot ask it to hit a target size; you can only give it fewer pixels. If a PNG has to reach 100 KB and it isn't a flat-colour graphic, converting it to JPG or WEBP is not optional, it's the whole solution. WebP often produces a smaller file than JPG at comparable visual quality (depending on image content), so if the destination accepts WebP you can often retain more detail inside the same 100 KB ceiling.
When 100 KB isn't achievable
Some images genuinely cannot hit the target while remaining useful: a detailed A3 scan, a screenshot of dense text, a panorama. In those cases the honest options are to reduce the dimensions further, split the image, or go back and ask whether the limit really applies. A tool that claims to hit any target on any image is simply not showing you what it destroyed.
Doing it on TryImager
Open the Image Compressor, switch to the Target size in KB mode, and enter 100 KB: the tool runs an automated binary search over encoder quality (and steps pixel dimensions down if quality alone cannot reach the ceiling) until the measured output is at or below 100 KB, displaying the exact byte count of the file you download. Everything runs in your browser tab, so personal ID photos and documents are never uploaded.
Why automated target-KB search beats manual slider guessing
Every photograph has a different entropy profile: a studio portrait against a white backdrop might drop under 100 KB at quality 86, whereas an outdoor group photo with trees and brick walls might need quality 68 or a dimension step down to 1000 px wide. Instead of exporting five test files by hand, Target size in KB mode measures the actual encoded Blob after each pass and converges on the highest quality setting that satisfies your ceiling.