Resize images to exact pixels, percentages or file sizes
Every platform wants a different image size. Instagram portrait posts are 1080 × 1350, YouTube thumbnails should be 1280 × 720, job and exam portals ask for photos “under 50 KB”, and a 4,000-pixel phone photo is far too heavy for an email or a web page. The Image Resizer changes the width and height of JPG, PNG, WebP, GIF and BMP images in one step, and can also squeeze the result under a target file size in KB.
Choose how you want to resize — exact pixels with the aspect ratio locked, a percentage, or a ready-made preset for social media, screens and passport photos — then download each picture or all of them as a ZIP. Resizing happens on your own device with the browser’s canvas engine, so private photos, ID scans and client work are never uploaded.
How to use the Image Resizer
- Drop one or more images on the upload area, click it to choose files, or paste a screenshot with Ctrl+V.
- Choose By pixels, By percentage or Preset size. With “Lock aspect ratio” ticked, type only the width or the height and the other side is filled in for you.
- For presets, or when you set both sides yourself, pick what happens if the shape differs: crop to fill, fit inside on a background colour, or stretch.
- Optionally choose an output format and quality, and type a target file size such as 100 KB.
- Check the new dimensions and file size under the preview, then press “Download”. Several images are bundled into one ZIP file.
Image Resizer features
Three ways to resize
Exact pixel dimensions, a percentage scale, or one-tap presets for Instagram, Stories, YouTube, Facebook, X, Full HD, 4K and passport photos.
Aspect ratio lock
Type one side and the other follows, so faces and logos are never squashed. In a batch, each image keeps its own proportions.
Crop, fit or stretch
When a preset has a different shape from your photo, crop the centre to fill the frame or fit the whole picture on a coloured background.
Target size in KB
Enter a limit and the tool searches for the highest JPG or WebP quality that fits, reducing the dimensions only if quality alone is not enough.
Sharp downscaling
Large reductions are done in halving steps with high-quality smoothing, which keeps fine detail and small text crisper than a single resample.
Batch and private
Resize dozens of photos with the same settings and download them together. Nothing leaves your device.
Common image sizes for social media, screens and documents
Use these pixel sizes as a starting point. Platforms adjust their layouts from time to time — the social media image sizes guide keeps a longer list, and the aspect ratio calculator turns any width and height into a ratio such as 16:9.
| Use | Size (px) | Aspect ratio |
|---|---|---|
| Instagram square post | 1080 × 1080 | 1:1 |
| Instagram portrait post | 1080 × 1350 | 4:5 |
| Story, Reel, WhatsApp status | 1080 × 1920 | 9:16 |
| YouTube thumbnail | 1280 × 720 | 16:9 |
| Facebook page cover (desktop) | 820 × 312 | about 2.6:1 |
| X (Twitter) header | 1500 × 500 | 3:1 |
| Full HD wallpaper or slide | 1920 × 1080 | 16:9 |
| 4K UHD | 3840 × 2160 | 16:9 |
| Passport photo, 35 × 45 mm at 300 DPI | 413 × 531 | 7:9 |
Pixels, DPI and print size
An image file stores pixels. DPI (dots per inch) is only an instruction for printing: the same 1200 × 1800 px photo prints at 4 × 6 inches at 300 DPI, or at 8 × 12 inches at 150 DPI. Changing the DPI number alone adds no detail, which is why this tool works in pixels.
To find the pixels you need for print, multiply the size in inches by the DPI, or divide millimetres by 25.4 and then multiply by the DPI. A 35 × 45 mm passport photo at 300 DPI is 35 ÷ 25.4 × 300 ≈ 413 px wide and 45 ÷ 25.4 × 300 ≈ 531 px tall. For a cut-out with the face sized and centred to official rules, use the passport photo maker.
How to resize a photo to 20 KB, 50 KB or 100 KB
- Set the pixel size the form asks for first — smaller dimensions are the most effective way to cut file size, and many portals specify both pixels and KB.
- Choose JPG as the output format. It is accepted almost everywhere and compresses photos well.
- Type the limit in “Target file size”. The tool lowers quality step by step and shrinks the image further only if it still does not fit.
- If the result looks soft, raise the KB limit a little or trim empty background first with Crop Image.
- The tool counts 1 KB as 1,024 bytes, like most upload forms, so a “50 KB” result is at most 51,200 bytes.
Upscaling and quality tips
Making an image larger than its original size cannot invent detail: the browser interpolates between existing pixels, so a 600 px photo enlarged to 1920 px looks soft. Enlarge only when a platform demands a minimum size.
Every JPG save re-compresses the picture, so keep your original and resize from it each time. If you only need a lighter file rather than smaller dimensions, use the image compressor.
Image Resizer FAQ
How do I resize an image without losing quality?
Keep the aspect ratio locked, resize from the original file rather than an already-resized copy, and use 85–92% quality for JPG or WebP. Reducing dimensions always discards pixels, but at normal viewing sizes the result looks just as sharp. Choose PNG if you need lossless output.
How do I resize an image to 1080 × 1080 for Instagram?
Choose “Preset size”, select “Instagram post (square) · 1080 × 1080” and keep “Crop to fill” to trim the sides of a landscape photo. Choose “Fit inside” instead if you want the whole photo with white or coloured borders.
Can this image resizer hit a specific size in KB?
Yes. Type the limit in “Target file size”. The image resizer finds the highest JPG or WebP quality that fits and, if needed, reduces the dimensions slightly. PNG has no quality setting, so for PNG only the dimensions are reduced.
Are my photos uploaded anywhere?
No. All resizing runs in your browser using the canvas API. Your images stay on your device, and the downloaded copies do not carry the original EXIF data such as GPS location.
Does resizing change the DPI?
Resizing changes the pixel dimensions, which is what screens and upload limits care about. DPI is just a print hint in the file’s metadata and is not copied from the original. If a form asks for 300 DPI at 2 × 2 inches, resize to 600 × 600 px — that is the same amount of detail.
Can I resize many images at once?
Yes. Drop several files together; they all use the same settings while keeping their own proportions. Press “Download all” to get a single ZIP file.