Image Compressor - Compress Image Size to 20 KB, 50 KB, 100 KB or Any KB

By the team at VidHaul

This image compressor makes a photo smaller in KB until it fits the limit you need. “Photo under 50 KB”, “signature 10 to 20 KB”, “document up to 200 KB”: exam forms, job portals and visa sites all ask for this, while a phone photo is usually several MB. Here you compress image size to 20 KB, 50 KB, 100 KB, 200 KB, 500 KB or 1 MB with one tap, or type any number in KB or MB. It also works as a bulk image compressor for up to 30 files and as a simple way to reduce image file size for email or Discord. Every photo is processed in your browser on your own device, so nothing is uploaded. Below we explain exactly how the tool picks the quality and pixel size, show measured results for common targets, and tell you when it cannot reach a size.

How does the image compressor work?

For each image the tool follows the same steps, taken straight from its code:

1. Already small enough? If the file is already under your target and already in the output format (for example a JPG with JPG chosen), it is kept as it is, because re-saving would only lose quality. You see “already under the target, kept as it is”.
2. Quick estimate. For big photos it first saves a small preview (about 250,000 pixels) at 50% quality and works out how big the full photo would be. If even that is clearly too big, it starts at a smaller pixel size right away, which saves time on phones.
3. Try the best quality first. It saves the image at 92% quality. If that already fits, you get 92%.
4. Search for the best quality. Otherwise it checks 50%. If 50% fits, it does a binary search between 50% and 92% (7 steps, so the quality is found to within about half a percent) and keeps the highest quality that is still under your size.
5. Shrink only if needed. If even 50% is too big, it makes each side smaller by the square root of the overshoot (times 0.92 for safety) and tries again, up to 8 rounds. File size grows roughly with the number of pixels, which is why the square root is used.

The target is counted with 1 KB = 1,000 bytes, so 50 KB means at most 50,000 bytes. That is stricter than 1 KB = 1,024 bytes, so the file passes both kinds of form.

Worked example (measured). In our own Chrome test we compressed a 2000×3000 phone JPG of 672.9 KB to the 100 KB target. Even 50% quality at full size was too big, so the tool reduced the pixels to 896×1344 and then found 76% as the highest quality that fits. The result was 97.9 KB, 2.1% under the target.

Compress image to 20 KB, 50 KB, 100 KB or 200 KB

These are the sizes forms ask for most. Here is what the compressor did with the same 2000×3000 phone photo (672.9 KB) at each target. All results are measured, not estimated.

A useful rule from these numbers: 20 KB gives a photo about 300 to 400 pixels wide, 50 KB about 600, 100 KB about 900 and 200 KB about 1,300. A plain photo with a white background keeps more pixels than a busy one. If you prefer a page with the size already set, use compress image to 20 KB, 50 KB, 100 KB or 200 KB.

Image compressor to 500 KB or 1 MB

Big targets are for email, websites and chat apps rather than forms. A typical phone photo reaches 500 KB or 1 MB at 92% quality without losing any pixels, or with only a small reduction. If your photo is already under the target and in the same format, the tool simply keeps it. For example, a 107.8 KB 600×900 JPG at the 200 KB target was kept unchanged in our test. By the same rule, our 672.9 KB test JPG is kept unchanged at the 1 MB target, while at 500 KB it is re-saved to fit.

Why didn’t my image get smaller?

There are two honest reasons:

• It was already under the target. You see “already under the target, kept as it is”. Choose a smaller target if you really want a smaller file.
• The target is impossible. Some images cannot get that small even at a tiny pixel size, for example a 5 KB limit for a large, detailed photo. Then you see “couldn’t reach the target; this is the smallest we could make it” and the size is shown in red. Try a slightly larger target, or crop away empty space before compressing.

A PNG under the target is still re-saved, because the output is JPG or WebP, not PNG. That usually makes it much smaller.

How to reduce image file size without losing quality

JPG and WebP are “lossy” formats: making them smaller always removes some detail. The aim is a loss you cannot see:

• Use the biggest size the form allows. At 100 KB our test photo kept 76% quality; at 20 KB only 52%.
• Start from the original. A photo that already went through WhatsApp or a screenshot has lost detail you can’t get back.
• Prefer fewer pixels over very low quality. The tool already does this: it stops lowering quality at 50% and shrinks the picture instead, because a small clean photo looks better on a form than a big blotchy one.
• Try WebP for websites. See the comparison below.
• Check the quality in the result. Above about 70% looks clean for most photos on a normal screen.

JPG or WebP: which compresses better?

Open More options to switch the output between JPG and WebP. On our test photo at 50 KB, JPG came out at 633×950 pixels and 61% quality, while WebP came out at 718×1076 pixels and 78% quality (49.4 KB). That is about 28% more pixels and clearly higher quality for the same size. A 70.2 KB WebP image compressed to 50 KB as WebP gave 49.9 KB at 1090×727 and 81%.

So why is JPG the default? Because almost every form, portal and app accepts JPG, and many do not accept WebP yet. Use JPG for forms, WebP for your own website or blog. JPG has no transparency, so transparent parts of a PNG become white; WebP keeps them.

How to compress an image for an online form

1. Read the form’s instructions for both the file size (KB) and the pixel size or ratio, and which formats it accepts.
2. If it gives pixels, such as 200 × 230, set them first in the image resizer with Exact size and Fill and crop. The compressor keeps your pixels whenever it can, so it won’t change them to match a form.
3. Type the KB limit here, or a little under it if the form gives a range like 20 to 50 KB. Don’t go below the lower limit; some portals reject files that are too small.
4. Compress the photo and the signature separately, each to its own limit.

Portals for SSC, UPSC, IBPS, NEET, state recruitment boards, passport and visa applications all work this way, but each one sets its own numbers, so always follow the form.

Bulk image compressor: up to 30 photos at once

Add up to 30 images and they are all compressed to the same target, one after another. Change the target or format and the whole list is redone automatically; there is no Start button. Use Download all (ZIP) to save them in one go. Files are named like photo-50kb.jpg so you can tell them apart. “Copy summary” copies every result line (name, size before and after, pixels, quality) as text, and “Copy link with these settings” under More options gives you a link that opens the page with the same target and format.

How to reduce image size on iPhone, Android, Mac and Windows

iPhone and iPad

Open this page in Safari, tap the box, pick the photo from Photos or Files and tap a size. HEIC photos are read on the device and saved as JPG or WebP. The download goes to the Files app.

Android

Open the page in Chrome, choose the photo from your gallery or files and tap a size. Downloads go to the Downloads folder.

Mac and Windows

Drag photos onto the box in Chrome, Edge, Safari or Firefox. You don’t need Photoshop, Paint or any other program to reduce image size in KB.

Image compressor for Discord and email

Chat apps and email have size limits too. Pick 1 MB or type a size in MB for the limit you need. For videos, use compress video for Discord or the general video compressor; for animated GIFs, use the GIF compressor, because this tool keeps only the first frame of a GIF.

How accurate is the image compressor?

When a target can be reached, the result is always at or under it, because every attempt is measured in real bytes before it is accepted. In our tests the results landed between 0.1 KB and 2.1 KB under the target (19.8 of 20 KB, 49.8 of 50 KB, 97.9 of 100 KB, 199.9 of 200 KB). Some honest limits:

• Pixel size is chosen for you. If the form needs exact pixels, use the resizer first.
• Very small targets. Below about 10 KB, a photo becomes small and soft. The tool never goes below 50% quality, so it shrinks pixels instead.
• Different browsers, slightly different results. Chrome, Safari and Firefox use their own JPG and WebP encoders, so the same target can give a slightly different pixel size or quality.
• Metadata. A compressed photo is re-drawn, so EXIF data such as location is not carried over. A file “kept as it is” is your original file, with its metadata; clean it with remove EXIF data if needed.
• GIF animation is lost (first frame only).

Why this tool is different

Most online image compressors upload your photo, run it through a fixed setting on their server and send it back. This one works in your browser: the image is drawn on a canvas and saved by the browser’s own JPG or WebP encoder, on your device. Your face, signature and ID documents are never sent anywhere.

It also aims at a size, not a slider position. Many tools let you pick “70% quality” and hope the file fits. Here you type the size the form asks for, and the tool measures real attempts until it finds the highest quality that fits, shrinking the pixels only as a last step. It refuses to re-save a file that already fits, and it counts KB the strict way. All of this is visible in the result line, so you can check it yourself.

What we measure

For each image, the tool measures its pixel width and height and its file size. During compression it measures the exact byte size of every attempt (quality and scale) and compares it with your target. The result shows the final size, pixels and the quality that was used, and whether the target was reached.

What we do not measure: we don’t score visual quality (no SSIM or similar test), we don’t look at what is in the photo, and we don’t check whether a portal will accept the file. We don’t collect any data about your images; the page has no way to send them anywhere.

Next steps: put several compressed photos into one file with the JPG to PDF converter, or turn iPhone photos into JPG with HEIC to JPG.

Only compress images you own or have the right to use.

Sources

• MDN: HTMLCanvasElement.toBlob(), the browser function that saves the JPG or WebP with a quality value from 0 to 1.
• MDN: createImageBitmap(), how photos are opened and turned upright from their EXIF orientation.
• Google: WebP, Google’s page on the WebP format and how it compares with JPEG.
• JPEG committee: JPEG (ISO/IEC 10918), the standard behind JPG files.
• MDN: Image file type and format guide.