Reduce Image Size
In KB — Free
Compress any image to an exact KB target. Enter your desired file size, click reduce, and download — no quality guesswork needed.
Drop your image here
or click to browse — JPEG, PNG, WebP
How it works
Upload Your Image
Select or drag a JPEG, PNG, or WebP image to get started.
Set Target File Size
Type in the maximum file size you need in KB — e.g. 100 KB or 50 KB.
Smart Compression
The tool binary-searches the perfect quality level to hit your target size exactly.
Download
Download the compressed image — all processing happens locally in your browser.
How to Reduce Image Size in KB
- 1Upload Your Image
Begin by uploading the image you need to reduce in size. Drag and drop or click to browse — JPEG, PNG, and WebP are all supported.
- 2Enter Compression Size
Enter the desired KB size you want your image compressed to. The default is 100 KB — you can choose any value like 20KB, 50KB, 200KB, or 500KB.
- 3Click Reduce Size
Click the "Reduce Size" button and wait a few seconds for the compression process to complete. Our algorithm automatically adjusts quality to hit your target.
- 4Download and Use
Once the resizing process is complete, download your newly compressed image at the desired KB size — ready for forms, emails, uploads, or social media.
Key Features
Resize images to exactly 100KB (or any target) with preserved clarity, eliminating oversized files.
User-friendly interface — resize images to any KB with just a few clicks. No technical expertise required.
Speedy compression ensures your images are ready for submission without delay — typically under 3 seconds.
Reduce JPEG to 20KB, 50KB, 100KB, 500KB, or any size you need — fully customizable target.
All processing happens in your browser. Your images never leave your device — 100% private and secure.
Supports JPEG, PNG, and WebP input. Output is always JPEG for maximum compression efficiency.
About Our Image Size Reducer
Reducing image file size to a specific kilobyte target is one of the most common needs for anyone submitting documents online — government forms, job applications, college admissions, ID verification, and social media profiles all impose strict file size limits.
UseToolify's Image Size Reducer uses a smart binary-search algorithm on the Canvas API's JPEG quality parameter. Instead of you guessing whether "70% quality" meets your 100KB limit, our tool automatically adjusts quality up and down until the output is as close as possible to your target — without going over.
Everything runs directly in your browser using HTML5 Canvas. Your image is never sent to any server, meaning your private documents, ID photos, and personal images stay completely on your device. There's nothing to install, no account required, and no watermarks added.
For images that are already smaller than your target KB, the tool will return the original without any quality degradation. For images that are significantly larger, our algorithm finds the optimal compression point that delivers the best possible visual quality at your required file size.
Common use cases: compressing a profile photo to under 100KB for a job portal, reducing a scanned document to 50KB for a government form submission, shrinking product photos for email attachments, or meeting social media upload size requirements.
You may also find our Resize Image, Convert JPEG to JPG, and Images to PDF helpful.
Looking for a free TinyPNG alternative? See how UseToolify compares.
Frequently Asked Questions
Can I compress an image to exactly 100KB?
Yes. Our algorithm uses binary search to find the JPEG quality value that produces a file as close to your target KB as possible, typically within 1–2KB of the target.
Does this work for PNG images?
Yes. PNG images are internally converted to JPEG for compression, which allows precise KB targeting. The output will be in JPEG format.
What is the minimum image size I can compress to?
The practical minimum depends on image dimensions. Very small images (e.g. 100×100px) may not compress below a few KB. For highly compressed targets, consider also resizing the image dimensions.
Are my photos uploaded to your servers?
No. All processing is done entirely in your browser using the HTML5 Canvas API. Your images never leave your device.
Will the image quality be affected?
Some quality reduction is inevitable when reducing file size, but our algorithm maximizes quality at your target size. For most portrait and document photos, the result is visually indistinguishable from the original.
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Guide
How to reduce an image to a specific size in KB
Online forms love hard limits: a job portal that accepts a photo only up to 50 KB, a bank KYC page that rejects anything above 200 KB, an email system that bounces a bulky attachment. This tool starts from that number. You tell it the largest file size you can accept, and it looks for the highest JPEG quality that still produces a file at or under that figure.
It changes only the compression level. The pixel width and height of your picture stay exactly as they were, and the result is always saved as a JPEG, whether you started with a JPEG, a PNG or a WebP. That is simple and predictable, but it also defines what the tool can and cannot do, which the tips and mistakes below spell out.
Step by step
- Drop an image onto the upload area or click it to browse. JPEG, PNG and WebP are accepted; any other type shows an error asking for one of those three. A preview appears along with the original size in KB.
- Under 'Target File Size (KB)', tap one of the presets (20, 50, 100, 200 or 500 KB) or type your own number. The box accepts values from 1 to 50000 and starts at 100.
- Click 'Reduce Size'. The tool re-encodes your picture at different quality levels, up to twelve attempts, narrowing in on the best quality that does not go over your target. It stops early once it lands within about 1 KB of the target.
- Check the two boxes that appear: 'Original' and 'Compressed', both shown in KB.
- Click 'Download Image'. The file is named after your original with the target added, for example passport-100kb-toolify.jpg. 'Reduce Another' clears everything for the next picture.
When this is useful
- Uploading a photograph to a recruitment or admission portal that states a maximum size in KB.
- Shrinking a scanned certificate or marksheet so it fits a government form's attachment limit.
- Making a phone photo small enough to attach to an email or a WhatsApp Business catalogue without waiting for it to send.
- Preparing a product picture for a marketplace listing that caps image files.
- Trimming a profile picture for a website or app that rejects large avatars.
Worked example: A 1600 x 1200 scan that must be 100 KB
The image has 1600 x 1200 = 1,920,000 pixels and the target is 100 KB = 102,400 bytes. That works out to 102,400 x 8 / 1,920,000, about 0.43 bits per pixel, which is a normal budget for JPEG, so the search succeeds and the quality settles somewhere in the middle (the first attempt is at 0.48, the midpoint of the 0.01 to 0.95 range, and it moves up or down from there). Compare a 4000 x 3000 phone photo with a 50 KB limit: 12,000,000 pixels give only 0.034 bits per pixel, which JPEG cannot reach at acceptable quality. Resizing that photo to 1280 x 960 (1,228,800 pixels) first lifts the budget to about 0.33 bits per pixel, and the same 50 KB target becomes realistic.
Tips for better results
- If a portal says 50 KB, aim slightly lower, such as 45. Some systems count a kilobyte as 1000 bytes while this tool uses 1024, so a file that looks fine here can be a hair over elsewhere.
- Very large photos need an extra step. Resize the dimensions first (for example with the Resize Image tool) and then compress, because a small number of pixels can reach a small file without destroying quality.
- Start from the original camera or scan file, not a copy that has already been compressed several times. Each round of JPEG compression adds visible blockiness.
- Right-click the downloaded file and check its properties. That is the number the portal will see, so it is worth confirming before you upload.
Common mistakes
- Asking for an impossible size. A 12-megapixel photo squeezed to 20 KB cannot be done at full dimensions; the tool bottoms out at its lowest quality and the file can still be larger than you asked. Reduce the pixel dimensions first.
- Using a transparent PNG. JPEG has no transparency, so see-through areas can turn black. Place the logo on a white background before compressing.
- Expecting the same file type back. The result is always a .jpg, which matters if a form insists on PNG.
- Compressing a screenshot of small text to a very low size. JPEG smudges sharp edges, so letters can become fuzzy; use a higher target or keep the image larger.
Your files and privacy
The image is read and re-encoded on a hidden canvas inside your browser, so the picture itself is not uploaded anywhere. When the page opens, the site records an anonymous usage event (the tool name and a random session ID), which does not include your file.
Frequently asked questions
Why is my result a little smaller than the target instead of exactly equal?
JPEG file sizes do not change smoothly with the quality setting, so the search settles on the highest quality that stays at or below your number. Landing within a kilobyte or two under the target is normal and is deliberate, so you never go over.
Does the tool change the width and height of my picture?
No. Only the compression level changes. If you also need different dimensions, use a resize tool first, then bring the result here to hit a KB limit.
What happens if my image is already smaller than the target?
The tool re-encodes it as a JPEG at high quality (0.95). If that copy is within your limit, it is returned as is, so you get a JPEG that is not necessarily smaller than your original file.
Can I get a PNG or WebP back?
No, the download is always a JPEG. That format is what makes precise size targeting possible, because its quality setting directly controls the file size.
The result is still over my limit. What now?
This happens when even the lowest quality cannot reach the number at your current pixel dimensions. Make the picture smaller in pixels with a resize tool, or pick a slightly higher target if the form allows it.
Will the picture look noticeably worse?
Lower targets mean more visible compression, especially around text, hair and fine patterns. Faces and ordinary photographs usually survive moderate reduction well; always look at the compressed preview before submitting.
Guide reviewed 2026-10-11 by the useToolify team.
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