Runs in your browser. Your files and text never leave your device - nothing is uploaded.
How do I compress an image to under 30KB?
To compress an image to under 30KB, resize it so the long side is about 550 pixels or less, then compress with a target size of 30KB so the quality is lowered only as far as needed. A passport-style portrait of around 400 × 530 pixels usually fits at good quality; a full-resolution photo will not.
30KB at a glance
- Exact limit: 30KB is 30,720 bytes, since the compressor counts 1KB as 1,024 bytes.
- Strict limit of 30,000 bytes: set the target to 29 instead.
- Balanced-quality pixel budget (about 1 bit per pixel): 0.25 megapixels, roughly 570 × 420.
- A 35 × 45 mm photo at 300 dpi (413 × 531) gets 1.1 bits per pixel. It fits at balanced quality.
- A 12-megapixel phone photo at full size gets 0.020 bits per pixel. That is too tight for a clean result, so resize first.
What a 30KB limit is usually for
30KB sits between the tight signature-sized slots and the roomier 50KB photo limits. It turns up on application forms that want a recent photograph at modest resolution, and it is a sensible budget for any photo that will only be shown small: staff directory headshots, membership cards, contact pictures and avatar uploads.
Forms that ask for a photo at this size often set a separate, lower limit for the signature, so read both before you start. The signature may need to go down to 20KB while the photo gets the extra 10KB.
How many pixels fit in 30KB?
With 30KB of room, a balanced-quality photo tops out at about 570 × 420. The 35 × 45 mm passport format at 300 dpi comes to 413 × 531, or about 219,000 pixels against a budget of about 246,000, so it can usually keep decent quality without any resizing.
| Compression level | Bits per pixel | Pixel budget | Square | 4:3 frame |
|---|---|---|---|---|
| Heavy compressionartifacts visible up close | ~0.5 | 0.49 MP | 700 × 700 | 800 × 600 |
| Balancedclean at normal viewing size | ~1 | 0.25 MP | 490 × 490 | 570 × 420 |
| High qualityhard to tell from the original | ~2 | 0.12 MP | 350 × 350 | 400 × 300 |
Each row divides the 245,760 bits in 30KB 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.
Fitting a portrait into 30KB
Start from the sharpest original you have rather than a screenshot or a photo of a printed photo, which carry extra texture and glare that cost bytes and look poor. Crop to the framing the form asks for, then resize to the requested pixel size, or to about 550 pixels on the long side if none is given.
With the target preset, press Compress Image and check the size printed on the result. The compressor tries quality levels between 5% and 100% over eight passes and keeps the best one that fits, so a file just under 30KB is the expected outcome, not a sign that too much was thrown away.
JPG is the safer output for forms. A JPG upload stays a JPG, but a PNG or WebP upload comes back as WebP, which many upload pages refuse. If yours does, convert to JPG first with PNG to JPG or the image format converter, then compress.
30KB compared with nearby sizes
| Target | Pixels at ~1 bit per pixel | Approx. 4:3 size | Compared with 30KB |
|---|---|---|---|
| 20KB | 0.16 MP | 460 × 340 | 0.67× the pixels, about 18% narrower and shorter |
| 30KB | 0.25 MP | 570 × 420 | Current target |
| 50KB | 0.41 MP | 730 × 540 | 1.67× the pixels, about 29% wider and taller |
30KB holds 1.5 times the pixels of 20KB, and 50KB holds two-thirds more again. For a 600 × 800 portrait that step matters: at 30KB it gets 0.51 bits per pixel, which means heavy compression, while at 50KB it would get 0.85, close to balanced quality.
Frequently asked questions
Usually, yes. A 35 × 45 mm photo at 300 dpi is 413 × 531 pixels, and at 30KB that works out to about 1.1 bits per pixel, enough for a clean JPG of a face on a plain background. Larger pixel dimensions will need heavier compression.
A small image can land well under 30KB even at the highest quality setting, and that is the file you get. If re-encoding would not make the file smaller than your original, the original is kept instead. Check the size shown: if it is under 30KB, upload it as it is; if not, resize first.
Use JPG unless the form lists WebP as accepted. WebP often looks better at the same size, but many upload forms take only JPG or JPEG. Compressing a JPG keeps it a JPG; PNG, WebP and GIF files are saved as WebP.
The compressor treats 30KB as 30,720 bytes. If a form counts 30KB as 30,000 bytes, a file of 30,500 bytes would pass here and fail there. Typing 29 keeps the result under both.
Other target sizes
Reviewed by Raja Jahangir · Last reviewed: October 7, 2026