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How do I compress an image to under 150KB?
To compress an image to under 150KB, resize anything larger than about 1,250 pixels on the long side, then compress with a 150KB target so JPEG quality is lowered only until the file fits. A 1280 × 960 photo typically lands there at good quality, while a 12-megapixel original needs resizing first.
150KB at a glance
- Exact limit: 150KB is 153,600 bytes, since the compressor counts 1KB as 1,024 bytes.
- Strict limit of 150,000 bytes: set the target to 146 instead.
- Balanced-quality pixel budget (about 1 bit per pixel): 1.2 megapixels, roughly 1280 × 960.
- A typical 4:3 web photo (1280 × 960) gets 1.0 bits per pixel. It fits at balanced quality.
- A 12-megapixel phone photo at full size gets 0.10 bits per pixel. That is too tight for a clean result, so resize first.
Good jobs for a 150KB image
150KB is as much a size you choose for your own pages as a limit someone else sets. It suits in-article images on a blog, photos in a knowledge-base or help-centre page, and product or property pictures in a listing grid before anyone clicks through.
If a form does set 150KB for a document photo, such as a certificate, an ID card or a proof-of-address page shot on a phone, legibility matters more than colour, and that changes how to prepare the image.
How many pixels fit in 150KB?
At 150KB the balanced row reaches 1280 × 960, a common size for web images, and heavy compression stretches to roughly 1810 × 1350. Notice how slowly the side length grows: 150KB holds 1.5 times the pixels of 100KB, yet the photo is only about 22% wider.
| Compression level | Bits per pixel | Pixel budget | Square | 4:3 frame |
|---|---|---|---|---|
| Heavy compressionartifacts visible up close | ~0.5 | 2.5 MP | 1560 × 1560 | 1810 × 1350 |
| Balancedclean at normal viewing size | ~1 | 1.2 MP | 1100 × 1100 | 1280 × 960 |
| High qualityhard to tell from the original | ~2 | 0.61 MP | 780 × 780 | 900 × 670 |
Each row divides the 1,228,800 bits in 150KB 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.
Preparing images for a 150KB target
For a photo going on a web page, size it to the column it sits in. A 750-pixel content column needs an image about 1,500 pixels wide to look sharp on a typical high-density screen; at 150KB that is 0.73 bits per pixel for a 4:3 photo, right at the edge. If the page never shows it that large, 1,200 pixels wide leaves more room for quality.
For a document photo, crop to the paper edges, shoot square-on in even light, and keep the shadow of your hand or phone off the page. Dim or uneven lighting adds sensor noise to the white paper, which costs bytes and blurs small print once compressed.
PNG screenshots and scans come back as WebP, which generally holds text up better than JPG at the same size. If the destination wants JPG, convert first with PNG to JPG and compress the result.
150KB compared with nearby sizes
| Target | Pixels at ~1 bit per pixel | Approx. 4:3 size | Compared with 150KB |
|---|---|---|---|
| 100KB | 0.82 MP | 1040 × 780 | 0.67× the pixels, about 18% narrower and shorter |
| 150KB | 1.2 MP | 1280 × 960 | Current target |
| 200KB | 1.6 MP | 1470 × 1100 | 1.33× the pixels, about 15% wider and taller |
150KB sits halfway between 100KB and 200KB in file size, but not in picture size: at balanced quality the width climbs from about 1,040 to 1,280 to 1,470 pixels across the three. If you are choosing your own target, the jump from 100KB is worth it for full-width images; for thumbnails it is not.
Frequently asked questions
Around 1.2 megapixels is a good rule of thumb for balanced JPEG quality, and 1280 × 960 is a typical example. Simple images with plain areas can go larger; detailed outdoor scenes may need to be smaller to look clean.
Often, if the scan is sized sensibly. An A4 page at 150 dpi is about 1240 × 1754 pixels, and text on clean white paper compresses well, so such a page can often fit 150KB and stay legible. Cropping away margins and shadows helps more than lowering quality.
JPG uploads stay JPG, but PNG, WebP and GIF uploads are saved as WebP. PNG cannot be compressed by lowering a quality setting, so WebP is used to make the target reachable while keeping any transparency.
Enter 146. The compressor counts 150KB as 153,600 bytes, so a file just under its 150KB target can still be over a 150,000-byte limit, whereas 146KB is 149,504 bytes and clears both.
Other target sizes
Reviewed by Raja Jahangir · Last reviewed: October 7, 2026