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How do I compress an image to under 100KB?
To compress an image to under 100KB, resize it to about 1,000 pixels on the long side if it is larger, then compress with a 100KB target so JPEG quality is reduced only as far as necessary. A 1024 × 768 photo usually fits at good quality; a full-resolution phone photo needs resizing first.
100KB at a glance
- Exact limit: 100KB is 102,400 bytes, since the compressor counts 1KB as 1,024 bytes.
- Strict limit of 100,000 bytes: set the target to 97 instead.
- Balanced-quality pixel budget (about 1 bit per pixel): 0.82 megapixels, roughly 1040 × 780.
- A square social-media image (1080 × 1080) gets 0.70 bits per pixel. It fits, but with fairly strong compression that can soften fine detail.
- A 12-megapixel phone photo at full size gets 0.068 bits per pixel. That is too tight for a clean result, so resize first.
Why so many uploads stop at 100KB
100KB is a round number that comes up constantly as an upload cap: photo fields on job and admission applications, profile pictures on professional networks and portals, attachments on support and ticketing systems.
On your own pages, 100KB is a reasonable budget for an inline blog image or a product photo in a grid. In email, nobody is fitting photos into 100KB to meet a limit, since attachment caps are measured in megabytes, but keeping each picture this small means a message with several of them still opens quickly on a phone.
How many pixels fit in 100KB?
The balanced row is the useful one here: about 1040 × 780, close to 1,000 pixels across. A 12-megapixel phone original has roughly 15 times as many pixels, which is why it cannot reach 100KB on quality alone.
| Compression level | Bits per pixel | Pixel budget | Square | 4:3 frame |
|---|---|---|---|---|
| Heavy compressionartifacts visible up close | ~0.5 | 1.6 MP | 1280 × 1280 | 1470 × 1100 |
| Balancedclean at normal viewing size | ~1 | 0.82 MP | 900 × 900 | 1040 × 780 |
| High qualityhard to tell from the original | ~2 | 0.41 MP | 640 × 640 | 730 × 540 |
Each row divides the 819,200 bits in 100KB by the bits per pixel, then fits that many pixels into a square and a 4:3 frame, rounded down to the nearest 10 pixels. Turn the 4:3 figure on its side for a portrait photo.
These figures are rules of thumb for JPG photos, not guarantees. Smooth skin, sky and plain walls need far fewer bits than foliage, fabric, small text or low-light grain, so the same pixel count can land well under or over the target. WebP, which PNG, WebP and GIF uploads are saved as, usually needs fewer bits than JPG for a similar look.
Getting a photo to 100KB in one pass
Most failed attempts at 100KB come from skipping the resize. Set the width to about 1,000 pixels in the image resizer, with the aspect ratio kept, then come back and compress. On a typical photo that combination lands at a quality where compression is hard to spot at normal viewing size.
For a website, consider whether WebP would serve you better. PNG and WebP uploads are saved as WebP, which usually reaches 100KB at a higher visual quality than JPG, and a JPG photo can be switched first with JPG to WebP. For forms, stay with JPG unless WebP is explicitly allowed.
Screenshots are the exception to most of this. Text and interface edges show compression artifacts quickly, so for a screenshot under 100KB, crop away everything that is not needed before compressing. Fewer pixels does more for legibility than a higher quality setting.
100KB compared with nearby sizes
| Target | Pixels at ~1 bit per pixel | Approx. 4:3 size | Compared with 100KB |
|---|---|---|---|
| 50KB | 0.41 MP | 730 × 540 | 0.5× the pixels, about 29% narrower and shorter |
| 100KB | 0.82 MP | 1040 × 780 | Current target |
| 150KB | 1.2 MP | 1280 × 960 | 1.5× the pixels, about 22% wider and taller |
100KB doubles the pixel budget of 50KB, which works out to about 41% more width and height: the step from a sharp profile photo to a sharp full-column blog image. 150KB adds half as much again on top.
Frequently asked questions
As a rough guide, about 0.82 megapixels at balanced JPEG quality, near 1040 × 780, and up to about 1.6 megapixels with heavy compression. Photos with fine texture fit fewer; simple graphics and plain backgrounds fit more.
Blockiness means the quality had to go very low, which happens when the image has several megapixels. Resize it to around 1,000 pixels wide and compress again; the result will usually look markedly better at the same 100KB.
Comfortably. Email attachment limits are measured in megabytes, so 100KB images are not about fitting a cap but about keeping messages quick to send and open, especially when several photos go in one email.
Yes. The compressor redraws the image on a canvas and saves only the pixels, so EXIF metadata such as GPS coordinates and camera details is not carried into the 100KB file. The original on your device keeps its metadata.
Other target sizes
Reviewed by Raja Jahangir · Last reviewed: October 7, 2026