What is Free Image Compressor?
Free Image Compressor is an online image compressor that makes JPG, PNG and WebP files smaller without making them look worse on screen. People use it most when a file is too big for where it has to go: a job or exam portal that rejects photos over 100 KB, 50 KB or 20 KB, an email attachment limit, or a website that loads slowly because of heavy images. You can pick a quality and see the estimated file size before you download, and set an exact width in pixels at the same time.
It runs in your browser, so the photo is never uploaded, and there's no signup or watermark. It's one of six free tools on Free Image Scaler, and below we show what it does to real photos, with the numbers we measured.
What this image compressor does, measured
This free image compressor makes photos smaller in two ways: by choosing a quality level and seeing the resulting file size before you download, or by typing the size you need in KB and letting the tool hit it. You can also set an exact width in pixels. Everything happens in your browser, so the photo is never uploaded, and there is no account, watermark or limit.
Here's a real example. We took an ordinary 8-megapixel phone photo of a cat: 3264 × 2448 pixels, 4.15 MB as a JPG. Set to 1080 pixels wide at 80 percent quality, it came out at 217 KB, a 95 percent reduction, and on a phone screen it is hard to tell from the original. Asked for "under 100 KB", the tool returned 99.2 KB at 869 × 652 pixels. Asked for "under 20 KB", it returned 19.8 KB at 365 × 274.
Those numbers already tell you the most useful thing on this page: small file sizes come mostly from fewer pixels, not from lower quality. Below we show exactly how quality, dimensions and format trade against each other, with the measurements, so you can pick settings with your eyes open instead of moving a slider until the number looks right.
How to compress an image
- Add your image. Drag a JPG, PNG or WebP onto the upload area or click to choose one. The original size and dimensions appear straight away.
- Choose a mode. "Quality %" gives you a slider and a live size estimate. "Target Size (KB)" takes a number and finds the best result under it. More on which to use below.
- Choose a format. JPG works everywhere; WebP is smaller at the same quality; PNG is lossless and only available in Target Size mode, where the tool can shrink it by reducing its dimensions.
- Optionally set a width. Type a width in pixels and the height follows to keep the shape; the label shows the resulting size, for example 1080 × 810 px. Leave it empty to keep the original dimensions. The tool never enlarges an image; for that, use the AI image upscaler.
- Compress. Press Compress Image. The result appears with its new size, the percentage saved and its dimensions.
- Download. The file is saved with "-compressed" added to its name. Your original is untouched, so you can try again with different settings.
In Quality % mode the estimate under the slider is not a guess: the tool actually encodes the image at that setting and reports the real size, so what you see is what you download.
What the quality slider really does
JPG and WebP are lossy formats. They throw away detail the eye is least likely to miss, mostly fine texture and subtle colour variation, and the quality setting decides how much. To see what that means in practice, we compressed the same 8 MP cat photo at every quality step and wrote down the size:
- 100%: 5.76 MB. Bigger than the 4.15 MB original.
- 90%: 2.02 MB
- 80%: 1.33 MB
- 70%: 1.05 MB
- 60%: 899 KB
- 50%: 784 KB
- 40%: 678 KB
- 30%: 569 KB
- 20%: 434 KB
- 10%: 264 KB
Three things stand out. First, the drop from 100 to 80 percent cuts the file by more than three quarters, while the steps below 60 percent save less and less. Second, 100 percent is a trap: it produced a file larger than the original, because the original was itself a compressed JPG, and saving it again at maximum quality spends bytes preserving the compression noise already in it. Third, even at 10 percent, which looks badly blocky, this photo was still 264 KB. If a form wants 100 KB, no quality setting will get a full-size phone photo there.
How much damage each step does
File size is only half the story, so we also measured how far each version strays from the original, using PSNR, a standard measure where higher means closer to the original (above about 40 dB differences are essentially invisible; around 30 dB they start to show on close inspection). On a 1024 × 1024 section of the photo:
- 95%: 42.2 dB
- 90%: 38.0 dB
- 80%: 34.5 dB
- 60%: 32.1 dB
- 40%: 30.8 dB
- 20%: 28.5 dB
- 10%: 25.8 dB
The curve is steep at the top and flat in the middle: going from 95 to 80 percent costs about 8 dB and halves the file, while going from 60 to 40 percent costs little visible quality but also saves little. In practice, 75 to 85 percent is the sweet spot for photos that people will look at closely, and 60 to 70 percent is fine for thumbnails, previews and email. Below 50 percent, smooth areas like skies, skin and walls start to show blocks and colour bands.
Why resolution matters more than quality
File size follows pixel count. Halve the width and height of a photo and you have a quarter of the pixels, and roughly a quarter of the file. We set the same cat photo to different widths, all at 80 percent quality:
- 3264 pixels wide (original): 1.33 MB
- 2048 wide: 620 KB
- 1920 wide: 554 KB
- 1280 wide: 280 KB
- 1080 wide: 217 KB
Compare that with the quality list: getting this photo to 217 KB by quality alone is impossible, but at 1080 pixels wide it happens at 80 percent quality, which looks clean. And 1080 pixels is not a compromise for most uses: it is the width Instagram displays, wider than most phone screens and wider than the text column of almost every website.
That's why Target Size mode works the way it does. It first tries to fit the limit by lowering quality, but never below 60 percent. If the image is still too large at 60 percent, it reduces the dimensions by exactly the amount the measured file size says is needed and tries again. The result is the largest, cleanest image that fits under your number, not a full-size image ruined by 10 percent quality.
Target Size mode: hitting 500, 100, 50 or 20 KB
Here is what the cat photo became at common limits, in JPG:
- Under 2000 KB: 1854 KB, still at full 3264 × 2448 size (only quality was lowered).
- Under 500 KB: 499.4 KB at 2231 × 1673.
- Under 200 KB: 197.3 KB at 1285 × 964.
- Under 100 KB: 99.2 KB at 869 × 652.
- Under 50 KB: 49.5 KB at 592 × 443.
- Under 20 KB: 19.8 KB at 365 × 274.
The tool lands just under the limit rather than far below it, so you get as much quality as the limit allows. In WebP the same targets gave slightly larger images (899 × 674 at 100 KB, 606 × 455 at 50 KB), because WebP stores the same detail in fewer bytes.
A tip for forms that dictate both a pixel size and a file size: set the width first, then the target. A photo set to 600 pixels wide with a 50 KB target came out at 600 × 450 and 49.1 KB; the tool only had to adjust quality. Our guides go deeper into specific limits: how to compress an image to 100 KB, to 50 KB and to 20 KB, each with what to expect at that size.
When a form also has a minimum size
Some upload forms reject files that are too small as well as too large. Indian government exam portals such as SSC, for example, have long asked for a JPEG photo between 20 and 50 KB and a signature between 10 and 20 KB. If your result comes out under the minimum (a small, plain image can compress very well), switch to Quality % mode and raise the quality, or set a larger width, until the estimate sits inside the range. Requirements change between exams and years, so always check the current notice for pixel sizes and other rules; some now capture the photo live during the application.
Four more images, four different results
One photo doesn't tell the whole story, so we ran four more very different images through the tool. Each one behaved differently, and each shows something worth knowing before you compress your own.
A portrait that was already compressed. A 3746 × 3746 pixel portrait downloaded from a photo site weighed only 419 KB, which for 14 megapixels means it had already been squeezed hard. At 80 percent quality it came out at 295 KB, so there was still something to gain. The real saving came from the width: at 1080 pixels wide and 80 percent it was 32 KB, a 92 percent reduction, and at that size it looked as good as the original on a phone. Large dimensions with a small file size are a sign that an image is ready to be resized rather than recompressed.
A small product photo. A 960 × 1280 photo of a mug, 117 KB, got slightly bigger at 80 percent quality: 119.8 KB. Its original was saved at a similar quality, so there was nothing to win by re-encoding it at the same size. Asked for 50 KB, the tool produced 49.9 KB at 687 × 916 pixels, still enough for a marketplace thumbnail. Small images don't have much fat to lose; to make one much lighter, you have to give up pixels.
A big camera photo. A 3765 × 2581 photo of a fishmonger, 6.51 MB, was 1.33 MB at 80 percent. Asked for 1000 KB, the tool kept the full 9.7-megapixel size and only lowered the quality, landing at 977 KB. Asked for 300 KB, it went to 2209 × 1515 pixels and 297.7 KB. Large, detailed photos give the tool the most room to work: you can often keep full resolution if your limit is around a megabyte.
A screenshot full of text. We made a 1080 × 1920 phone-style screenshot with 40 lines of text. Saved as PNG by the browser it weighed 820 KB. With a 100 KB target, the PNG version had to shrink to 182 × 324 pixels, where the text is unreadable. The JPG version stayed at 469 × 834 and the WebP version at 537 × 956, both still legible. For screenshots that have to meet a size limit, JPG or especially WebP keeps the text readable at a much larger size than PNG can. Without a limit, PNG remains the crispest choice.
JPG, WebP or PNG?
- JPG is the safe choice. Every website, form, email program and printer accepts it, and it handles photos well. Choose it whenever you are not sure what the destination supports. It has no transparency: if your image has see-through areas, they are filled with white.
- WebP gives more quality per byte. At almost the same size, our WebP version scored about 3 dB higher than JPG (220 KB at 36.4 dB against 206 KB at 33.1 dB), which is a visible difference in smooth areas. At 80 percent quality the full-size photo was 978 KB as WebP against 1.33 MB as JPG. Use it for websites and anywhere it's accepted; avoid it for government portals, older software and print shops unless they say they take it.
- PNG is lossless: it never loses detail, so it has no quality setting, and the only way to make a PNG smaller is to make it smaller in pixels. That's why it's only offered in Target Size mode. PNG is the right format for screenshots, logos, diagrams and anything with transparency, and the wrong format for photos. If you need a small file from a photo, convert it to JPG or WebP.
How image compression works, in plain words
You don't need to know this to use the tool, but it explains almost every result above, including the strange ones.
JPG splits the picture into a brightness channel and two colour channels. Our eyes are much more sensitive to brightness than to colour, so JPG usually stores the colour at half the resolution in each direction and nobody notices. Then it cuts the image into 8 × 8 pixel blocks and describes each block as a mix of simple patterns, from flat to finely striped. The quality setting decides how precisely those patterns are recorded. At high quality, fine stripes are kept; at low quality, they're rounded away, and each block drifts towards a flat colour. That's why heavily compressed JPGs look blocky, and why you see faint ripples around sharp edges like text: the fine patterns that would make the edge crisp were thrown out.
WebP (in its usual lossy mode) comes from video compression. Instead of describing every block from scratch, it predicts each block from the pixels around it and stores only the difference, which is often small. It also smooths the borders between blocks after decoding. As a result, a WebP at the same file size usually has fewer visible artifacts, and when it does fall apart it looks soft rather than blocky. That's the 3 dB advantage we measured.
PNG never throws anything away. It looks at each row of pixels, predicts it from the row above or the pixel to the left, and then zips the result, the same way a ZIP file shrinks a document. That works brilliantly when large areas are identical (a white background, a flat button, a line of text on a plain colour) and poorly on photos, where neighbouring pixels are almost never exactly equal. A photo saved as PNG can easily be five to ten times the size of a good JPG.
Two practical consequences follow. Photos belong in JPG or WebP, graphics with flat colour in PNG or WebP. And once detail has been thrown away by a lossy format, no setting brings it back: compressing again only removes more. If you need a bigger or sharper version later, go back to the original, or use the AI image upscaler, which rebuilds detail rather than recovering it.
Why some images barely compress, and some get bigger
A few situations surprise people, so here's what's going on in each.
The file got bigger. If the original was already a compressed JPG, re-saving it at high quality (90 percent and up) can produce a larger file, as our 100 percent test showed. Lower the quality to 80 percent or less, or set a smaller width.
A PNG screenshot won't shrink much. Screenshots and graphics are already efficient as PNG. Converting them to JPG often helps less than you'd think and makes text look smudged. Reducing the width helps more; so does WebP, which handles both photos and flat graphics well.
A photo of noise, grass or gravel stays large. Fine random detail is the hardest thing to compress. A photo of a lawn at the same pixel size can easily be twice the file of a photo of a clear sky. Resolution is your main lever for these.
A small image is already tiny. A 400 × 400 profile picture might be 40 KB to begin with. There is little left to save, and pushing it lower costs visible quality quickly.
Compressing several photos
The tool works on one image at a time. For a handful of photos that's quick: choose your settings once, add an image, compress, download, add the next. The mode, width and target size stay as you set them when you switch images, so you don't have to type them again. Only the format switches to match each new image's format, so give it a quick glance. For hundreds of photos at once, such as a whole album for a website, a program with batch processing is the better choice.
Don't compress the same file twice
Every lossy save throws away a little more. Compressing an already-compressed JPG, then compressing that result again, adds up: the blocks and bands get worse each time while the file barely shrinks. Always start from the best version you have, the original from your camera or phone, and compress once, to the size you actually need.
The same goes for the order of operations when you edit. Crop and fix the photo first, compress last. If you crop the image after compressing it, the cropper saves it again and the file can grow. If you are going to remove the background or upscale a small photo, do that before compressing too; both work better on clean, full-quality pixels.
What size should your image be?
The right size depends on where the image is going. Some useful reference points:
- Email. Gmail allows attachments up to 25 MB per message and Outlook up to 20 MB, but several full-size phone photos fill that quickly, and large attachments are slow on mobile data. For photos meant to be viewed on screen, 1600 to 2048 pixels wide at 80 percent quality (roughly 300 to 600 KB for a typical photo) looks sharp on any screen.
- Website content images. An image in the text column of a blog or shop is rarely displayed wider than about 800 to 1200 pixels. Serving 1200 to 1600 pixels covers sharp high-density screens; at 75 to 80 percent JPG, or WebP, most photos land between 100 and 300 KB.
- Full-width website banners. 1920 pixels wide is enough for most screens; aim for 200 to 400 KB. Large hero images are often the slowest thing on a page.
- Social media. Platforms recompress everything you upload, so there's no point sending them a tiny, heavily compressed file: you'd be compressing twice. Upload at the size they display (1080 pixels wide for Instagram) at high quality and let them do the rest. The Instagram image size guide lists the exact dimensions.
- Messaging apps. WhatsApp and similar apps already shrink photos when you send them normally, often a lot. Compressing first gains little and means the photo is compressed twice. To send a photo in better quality, use the app's HD option or send it as a document; then the file arrives unchanged, including its metadata.
- Online forms and portals. Follow the stated limits exactly, both pixel size and KB. Target Size mode with a width set is made for this.
- Marketplace listings. Many marketplaces need at least 1000 pixels on the longest side for zoom; around 1600 pixels at 80 percent keeps files manageable without losing that.
Images and website speed
On most websites, images are the largest part of what a visitor downloads, and an oversized photo is one of the most common reasons a page feels slow. Google measures how quickly the largest element on the screen appears (it calls this Largest Contentful Paint) as part of its Core Web Vitals, and on many pages that element is an image. A 4 MB photo straight from a phone, shown 800 pixels wide, makes every visitor download about twenty times more than they can see.
The fix is simple and makes a bigger difference than most technical tweaks: before you upload, set the width to roughly the largest size the image will appear, and compress to 75 to 85 percent. If your site supports WebP, use it. Our test photo went from 4.15 MB to 217 KB at 1080 pixels wide without visible loss, which on a slow mobile connection is the difference between a photo that appears at once and one that loads line by line.
Two habits help further. Keep the original files somewhere safe, because if you later need a larger version you want to start from the original rather than enlarge a compressed copy. And remove camera metadata from images you publish: it adds weight and can include the location where the photo was taken. Images saved by this compressor already have it removed, as we explain next.
Privacy: what happens to your photo
The compression runs on your device, in your browser. The image is never uploaded to a server, which matters for ID photos, documents and personal pictures that you wouldn't want stored somewhere else.
Compressed files also come out without the camera metadata of the original. We checked every file from our tests: none contained EXIF data or GPS coordinates, because the image is redrawn and saved as a new file. Phone photos that were stored sideways come out with the rotation applied to the pixels, so they still display upright everywhere. If you want to remove metadata without compressing at all, so with no change to the image, use the metadata remover, which strips it losslessly and shows you what was there. Our guide to what EXIF data is explains what those hidden fields contain.
Compressing images for forms, step by step
Forms are where most people meet a file size limit, usually with an error message and no explanation. A routine that works:
- Read the requirement carefully. Note the format (usually JPG), the file size range (for example 20 to 50 KB), and any pixel dimensions or physical size (for example 35 × 45 mm for a photo).
- If the photo has to be a specific shape, crop it to the right ratio first. Our passport photo size guide lists common ID photo dimensions.
- Open the cropped image here. If pixel dimensions are given, type the width.
- Switch to Target Size, choose JPG and type the upper limit, or a few KB below it to be safe.
- Check the result: is it inside the range, and does the face or text still look clear? If it's below a minimum, use Quality % mode and raise the quality.
- Download and upload. Keep the file in case the form asks again.
For signatures, scan or photograph them on plain white paper in good light, crop tightly around the signature, and then compress. A tight crop removes empty paper, which costs bytes without adding anything.
Troubleshooting
"Could not fully reach … KB"
The tool shrinks the image until it fits, but stops at 16 pixels on the shortest side. You'll only see this message with very small targets on very large or detailed images, or with PNG files, which can only shrink by losing pixels. Choose JPG or WebP, or accept a slightly larger target.
The image looks blocky or has colour bands
The quality is too low for this image. In Quality % mode, move the slider up to 70 or 80 percent; in Target Size mode, set a smaller width so the tool can keep the quality higher, or allow a larger file.
Transparent areas turned white
JPG can't store transparency, so see-through areas are filled with white. Choose PNG or WebP to keep them transparent.
The estimate shows "calculating…" for a while
The estimate is a real encode of the whole image, so on a very large photo or a slow phone it can take a second or two. Setting a width first makes it faster.
Target Size takes a few seconds
It tries several quality settings and sizes to find the best fit, encoding the image each time. Expect a few seconds for large photos; it's still faster than trial and error by hand.
My photo won't open
The tool accepts JPG, PNG and WebP. iPhone HEIC photos need converting to JPG first; on the iPhone, Settings, Camera, Formats, Most Compatible makes the camera save JPG from then on.
If your problem isn't covered here, the troubleshooting page has fixes for every tool on the site.
How it compares with other ways to compress
Server-based online compressors upload your image, compress it on their machines and send it back. Many do a good job, but your file leaves your device, free tiers often limit file size or count, and you can't see the quality-size trade-off before you commit.
Squoosh, Google's open-source web app, also compresses in the browser and offers a side-by-side comparison and advanced codec settings. It's excellent for one image when you want fine control; it doesn't take a target size in KB.
Photo editors like Photoshop, GIMP or Affinity Photo have export dialogs with quality and size settings. If the image is already open there, export from there.
Your phone's share options sometimes offer "small, medium, large" when emailing photos. That's quick, but you don't know the resulting size or quality.
This tool is built for the common case: you have a photo and a limit, or a photo and a page it needs to load quickly on. You see the real size before downloading, you can ask for an exact KB limit, you can set the width, and nothing is uploaded.
Related tools and guides
- In depth: how to reduce image file size without losing quality, with the numbers we measured.
- Limits by size: compress an image to 100 KB, to 50 KB and to 20 KB.
- Need a specific shape first? Use the image cropper, and check the passport photo size guide for ID photos.
- Image too small rather than too big? The AI image upscaler enlarges it, and the guide on how to increase image resolution explains what to expect.
- Selling online? Make the photo clean with the background remover, then compress for your shop.
- Sharing photos publicly? Remove hidden location data with the metadata remover.