Compress Image to 300kB

Yes, for almost everything except a downloadable print file. At 300 kB you can serve a 1,600 px wide header or a 2,000 px product photo at a quality the eye reads as original, so the size suits featured images, hero banners, product galleries and in-post photos alike. The reason to go lower is volume, not quality: a page with twenty 300 kB thumbnails is 6 MB of pictures before any script or font, and the median mobile home page already carries about 911 kB of images (HTTP Archive, July 2025). On dense pages keep 300 kB for the one big picture that forms the LCP element and take the small tiles down to 250 kB or less.

Around 1,200 × 800 px is the comfortable zone: a photo of any subject fits 300 kB at that size with quality to spare. Go to 1,600 × 1,067 px for full-width headers and 1,920 × 1,080 px for slides – most photos still land under the target at a good setting. Beyond that it depends on content. A sky, a studio portrait or a product on white has smooth areas that compress well and can run 2,000–2,400 px wide, while foliage, crowds, fabric patterns or a busy street cannot, and the tool will scale those down until the quality stays above roughly 45%. Set fit within to the width you actually display and let it sort out the rest.

WebP, when the image lives on a site you control. Google's measurements put lossy WebP 25–34% below a JPEG of matching visual quality, so the same 300 kB holds a larger or cleaner picture, and caniuse shows WebP working in about 97% of browsers in use (October 2026); add a JPG fallback with <picture> if you still support very old devices. Choose JPG when the file leaves the web: newsletters, slide decks, marketplace uploads and client hand-offs all take JPG without question, while some still reject WebP. The Auto setting in Mb2KbSizer follows the same logic – WebP in stays WebP, everything else becomes JPG – and you can override it under Format & dimensions.

Yes. A 5 MB phone photo is usually 12 to 24 megapixels, and nothing on a web page, in an email or on a slide displays anywhere near that many pixels. Mb2KbSizer first tries to reach 300 kB by lowering the JPEG quality alone; when that would mean a blocky result (below roughly 45%), it shrinks the dimensions in clean steps – usually to about 1,600–2,000 px on the long side – and searches again until it lands at or just under 300 kB. That is a saving of about 94%, and the before/after slider lets you confirm that the difference is invisible at normal viewing size.

No. Gmail, Outlook.com and Yahoo Mail accept 25 MB per message and iCloud Mail 20 MB, so even ten 300 kB images – 3 MB, or roughly 4 MB after the base64 encoding that email applies to inline pictures – sit far inside those limits. The constraint that matters is the reader: images that download slowly on mobile data get scrolled past, and Mailchimp's own recommendation is a maximum of 1 MB per image. Keeping each picture at 300 kB and 600–1,320 px wide means the newsletter opens fully before the reader loses interest.

No. We have no image storage of any kind, because the file never reaches us in the first place. It sits in your browser's memory while you work, and the compressed version exists only on your device once you download it. Close or refresh the tab and both are gone. We keep no history, no gallery and no cache on our side, and we cannot see what you compress. Our web host records ordinary server logs, such as the time of a page visit and the browser used, but those cannot contain your pictures. For the full detail, read our privacy policy.

Mb2KbSizer is a free image and PDF compressor that runs inside your web browser. You pick a file, type the size you need, such as 100 kB, and it shrinks the file to land at or just under that number. Most people use it for upload forms that reject big files: exam registrations, passport and visa applications, job portals, bank KYC and college admissions. It is just as handy for lightening photos before you email them or put them on a website. There is a [single-image tool](/), a bulk compressor for up to 200 photos at once, and a PDF compressor, all built on the same no-upload principle.

Yes. Every tool on this site is free, and we intend to keep it that way. There is no sign-up, no premium tier, no daily quota and no watermark on the output. Compress one photo or three hundred; nothing counts against a limit. A few ads on the page pay for hosting. Because the heavy lifting happens on your own device rather than on our servers, each extra user costs us almost nothing, so there is no reason to charge. We do not sell an app, a plan or an API either, so you will never be nudged towards a paid version.

No installation is needed. Mb2KbSizer is a web page, so it works the moment it loads in current Chrome, Edge, Firefox, Safari or Samsung Internet on a phone, tablet or computer. Nothing is downloaded to your device except the page itself, and it does not ask for storage or camera permissions. If you use the tool often, you can add it to your phone's home screen from the browser menu and it will open like an app. It still needs an internet connection to load, though, so treat this as a shortcut rather than an offline program. There is no Play Store or App Store version.

Three steps, usually under a minute.

1. Add your photo. Drag it onto the upload box, tap browse to pick it from your gallery, or paste it from the clipboard with Ctrl/Cmd + V.
2. Set the target. Type a number and choose kB or MB, or tap a quick chip from 20 to 350 kB. On a preset page the field is already filled in. If a form demands exact pixel dimensions, set them in the resize option.
3. Press Compress, then Download. You get a before/after slider, the output dimensions, the quality used and the exact byte count, so you know it will pass before you submit it.

You can upload JPG, PNG, WebP, GIF (the first frame is used), BMP and AVIF, provided your browser can decode the file. HEIC photos from an iPhone open in Safari and other browsers with HEIC support; elsewhere the tool explains how to set the camera to Most Compatible so new shots are saved as JPG. Files up to 60 MB are accepted. For output, Auto gives a JPG in most cases and keeps WebP as WebP; you can also force JPG, WebP or PNG. PNG is lossless, so a PNG target is reached only by reducing dimensions, which is why JPG is the better pick for a small photo.

Strictly speaking, you never upload anything. When you choose a file, the browser reads it from your device and does the resizing and re-encoding in a background worker on that same device. No copy travels to our server or to anyone else's; the only thing our server sends you is the page. A useful side effect is that the browser rebuilds the image from its pixels alone, so EXIF data such as the camera model, the date taken and the GPS location is dropped from the output. That makes the compressed photo safer to share than the original you started with.