Image Resizer
Resize photos by pixels or percentage and save as JPG, PNG or WebP
How to Use
- Drop a photo on the box or tap it to choose one (JPG, PNG, WebP or GIF). It opens on your device; nothing is uploaded.
- Choose Pixels and type a new width or height (with Keep aspect ratio on, the other side follows), or choose Percentage and pick a scale such as 50%.
- Pick the output format (JPG, PNG or WebP) and, for JPG or WebP, set the quality slider.
- Tap Resize image. The original and new dimensions and file sizes appear with a preview.
- Tap Download to save the resized image.
What does an image resizer do?
An image resizer changes the number of pixels in a picture: its width and height. A photo from a modern phone is often 4000 × 3000 pixels (12 megapixels) or larger, which is far more than you need for WhatsApp, an email, a website or most online forms. Making it smaller in pixels also makes the file much smaller, so it uploads faster and takes less space.
This tool works entirely in your browser using the <canvas> element. Your photo is never sent to a server, which matters for ID cards, certificates and personal pictures.
How the aspect ratio is kept
The aspect ratio is the shape of the picture: width divided by height. If you change only one side and leave the other, the picture gets squashed or stretched. With Keep aspect ratio on, the tool works out the other side for you:
New width = New height × (Original width ÷ Original height)
The result is rounded to the nearest whole pixel. In Percentage mode both sides are multiplied by the same factor, so the shape never changes.
Worked example
You have a 4000 × 3000 photo and want it 1600 pixels wide for a website.
The resized image is 1600 × 1200, which is 1.92 megapixels instead of 12: about one-sixth of the pixels. Saved as a JPG at 85% quality, a typical photo of that size is a few hundred KB instead of several MB, though the exact size depends on how much detail the picture has.
Percentage sizes for a 12 MP phone photo
| Scale | Size (from 4000 × 3000) | Megapixels |
|---|---|---|
| 100% | 4000 × 3000 | 12.0 |
| 75% | 3000 × 2250 | 6.75 |
| 50% | 2000 × 1500 | 3.0 |
| 25% | 1000 × 750 | 0.75 |
Notice that halving both sides leaves only a quarter of the pixels. That is why a 50% resize usually cuts the file size by much more than half.
Choosing JPG, PNG or WebP
| Format | Best for | Transparency | Quality slider |
|---|---|---|---|
| JPG | Photos; forms and portals that accept only JPG/JPEG | No (becomes white) | Yes |
| PNG | Screenshots, logos, text, images with transparency | Yes | No (lossless) |
| WebP | Websites and apps that support it; smallest files | Yes | Yes |
The quality slider controls JPG and WebP compression. Around 80–90% looks the same as the original to most people; lower values give smaller files with visible blur or blockiness, especially around text and sharp edges.
Sideways photos are fixed automatically
Phones often store a photo in one direction and add an EXIF "orientation" tag that says how to turn it. Some tools ignore the tag, so the resized picture comes out sideways. This resizer reads the orientation first (using createImageBitmap with imageOrientation: "from-image"), so the output looks the way it does in your gallery. Saving through the canvas also drops other EXIF data, including GPS location.
Tips
- Avoid enlarging. Making a small picture bigger cannot add detail; it only makes it softer.
- Resizing vs compressing: resizing reduces pixels; compressing lowers quality at the same pixel size. If you need a file under a fixed KB limit, use the Image Compressor's target-size mode.
- Exam and government forms usually need an exact pixel size and a KB range. Use the Exam Photo & Signature Resizer, which crops and compresses to both at once.
- Very large outputs may fail on phones: iPhone browsers cap a canvas at about 16.7 megapixels (for example 4096 × 4096).