Image Resizer
Resize JPG, PNG and WebP images to exact pixels, a percentage or a social media size, and shrink them to a target file size in KB.
Runs 100% in your browser
Drop an image here
or
JPG, PNG, WebP, GIF · processed on your device
Original:
Almost every website, form and social network has its own rules for images: a maximum width, an exact aspect ratio or a file size limit in kilobytes. This free Image Resizer changes the dimensions of your photos in pixels or by percentage, crops them to popular social media sizes and can squeeze them under a target file size, all inside your browser. Your pictures are never uploaded to a server.
How to resize an image
- Add your image. Drop a JPG, PNG, WebP or GIF onto the box or press Choose image. The original size appears straight away.
- Choose the new size. Type a width or height with Keep aspect ratio on, switch to Percentage, or pick a preset such as Instagram portrait or YouTube thumbnail.
- Pick a format and limit. Choose JPG, PNG or WebP. To meet an upload limit, enter a maximum size in KB and the tool finds the best quality that fits.
- Resize and download. Check the preview and the final size, then press Download.
Pixels, aspect ratio and cropping
A digital image is a grid of pixels. Its aspect ratio is width divided by height: most phone photos are 4:3 or 16:9, while Instagram portrait posts are 4:5. When Keep aspect ratio is on, you set one side and the tool calculates the other, so nothing is stretched. If you need an exact size with a different ratio, such as turning a landscape photo into a 1080 × 1080 square, turn the lock off and tick Crop to fill. The tool then scales the image until it covers the whole frame and trims the edges evenly from the centre, the same "cover" behaviour used by most websites. Without cropping, an unlocked resize stretches the picture.
Why downsizing quality matters
Shrinking a large photo in one jump can produce jagged edges and shimmering patterns, because each new pixel is averaged from too few original pixels. This resizer reduces the image in halving steps with high-quality smoothing before the final size, a technique that keeps fine detail like hair and text crisp. Enlarging is possible too, but no tool can invent detail that the camera did not capture, so upscaling more than about 150 percent will look soft.
Common image sizes
| Use | Size (px) | Ratio |
|---|---|---|
| Instagram square post | 1080 × 1080 | 1:1 |
| Instagram portrait post | 1080 × 1350 | 4:5 |
| Stories, Reels, Shorts, TikTok, status | 1080 × 1920 | 9:16 |
| YouTube thumbnail | 1280 × 720 | 16:9 |
| Link preview (Open Graph) | 1200 × 630 | 1.91:1 |
| X (Twitter) header | 1500 × 500 | 3:1 |
| LinkedIn personal banner | 1584 × 396 | 4:1 |
| Full HD screen | 1920 × 1080 | 16:9 |
Platforms update their recommendations from time to time, so check the help centre of the service if an upload looks cropped. YouTube, for example, recommends 1280 × 720 thumbnails under 2 MB, and the Open Graph size of 1200 × 630 is what most social networks and messaging apps use for link previews.
Resizing to a file size in KB
Many job portals, university applications and government forms around the world ask for a photo "under 100 KB" or "between 20 and 50 KB". File size depends on both the number of pixels and the compression. Enter a value in Max size KB and the tool repeatedly encodes your image as JPG or WebP, searching for the highest quality that stays under your limit. If even the lowest sensible quality is too large, reduce the width and height as well; halving both sides cuts the pixel count to a quarter. PNG is lossless, so it ignores the KB target; use JPG or WebP when size matters.
JPG, PNG or WebP?
- JPG is best for photos and is accepted everywhere. It does not support transparency, so transparent areas become white.
- PNG keeps every pixel exactly and supports transparency. It is ideal for logos, screenshots and graphics with text, but photos become large.
- WebP, developed by Google, usually gives smaller files than JPG at similar quality and supports transparency. All current major browsers support it, though some older software and upload forms do not.
Privacy
The resizer uses the HTML canvas built into your browser. Your image is read from your own device, processed in memory and saved back to your downloads folder; nothing is uploaded. Saving a resized copy also strips most metadata, such as camera details and GPS location, which is useful before sharing photos publicly.
Frequently asked questions
Will resizing reduce the quality of my photo?
Making an image smaller keeps it sharp with this tool. Enlarging it beyond its original size cannot add real detail, so it will look softer. Choosing a lower JPG quality or a tight KB limit adds compression artefacts.
How do I resize an image to 50 KB or 100 KB?
Choose JPG or WebP, type the limit in Max size KB and press Resize. If the result is still too big, lower the width and height and try again.
Are my images uploaded?
No. Everything happens in your browser on your own device. You can disconnect from the internet after the page loads and the tool still works.
Can I resize several images at once?
This version handles one image at a time to keep memory use low on phones. Repeat the steps for each image; your settings stay in place.
Why does my PNG keep a large file size?
PNG is lossless, so the KB target does not apply. Convert it to JPG or WebP to make the file smaller.
What is the largest image I can resize?
Up to 12,000 pixels per side. Very large images may be slow on older phones because the browser must hold them in memory.
Sources
- MDN: CanvasRenderingContext2D.imageSmoothingQuality
- MDN: HTMLCanvasElement.toBlob()
- YouTube Help: Add video thumbnails
- Google for Developers: WebP
- The Open Graph protocol
Related tools
By Abdullah Al-Janoubi · WorldScope Tools · Updated October 2026
Comments