🖼️ Image Resizer
Resize images online in your browser — change width, height, or scale with the Canvas API. Free, private, no upload.
Need to shrink a photo for a website, resize a product image for a marketplace, or scale down a huge screenshot before sending it by email? Our Image Resizer resizes images directly in your browser using the Canvas API — you pick the new width and height (or a percentage), and the tool produces a properly scaled JPG, PNG, or WebP file you can download instantly.
The conversion happens entirely on your device. You select a file, the image is decoded, redrawn at the new dimensions, and encoded to your chosen format — nothing is uploaded to any server. That makes it safe for private photos, documents, and anything else you don’t want leaving your machine.
Real-world uses: resizing a product photo to the exact pixel size a shop requires, compressing a phone screenshot for a forum or helpdesk ticket, creating a consistent set of thumbnails for a gallery, or scaling an image down so it loads faster on a web page. The tool preserves the aspect ratio by default (just type a width), but you can also enter both width and height explicitly or scale by a percentage.
One honest note: while this tool genuinely redraws the image (it doesn’t fake the resize), a quality lossless resize is only possible when you scale down or keep the same dimensions. Scaling a small image up creates new pixels and softens detail — no tool can invent detail that wasn’t in the original. For the best result, resize down from the largest original you have.
How the conversion works
Behind the scenes this tool uses the standard HTML5 Canvas API that ships with every modern browser. When you pick a file, the browser decodes your image into an in-memory bitmap, redraws it onto a fresh canvas at your chosen dimensions, and then encodes the result as a JPG, PNG, or WebP file you can download. Because the entire pipeline runs on your device, the only "server" involved is your own browser — nothing is ever uploaded.
To keep the scaled result from looking jagged, the redraw is done with image smoothing enabled at high quality, so neighboring pixels are blended as the image is scaled. You control the output in a few straightforward ways:
- Width only — type a width and the height is computed automatically to preserve the original proportions.
- Height only — the mirror case; the width is derived from the height to keep the aspect ratio.
- Both width and height — forces exact dimensions, which can stretch or squash the image if the numbers don't match the original ratio.
- Scale % — a quick multiplier that sizes the image up or down relative to the current dimensions.
The automatic calculation is simple: when you enter only a width on an image, the height becomes original height ÷ original width × new width. For example, typing a width of 800 on a photo that is 4000 × 3000 px produces a height of 3000 ÷ 4000 × 800 = 600 pixels.
Worked examples
Here are real, hand-calculated examples so you know exactly what to expect before you start:
- A 4000 × 3000 photo resized to a width of 800 px. Height = 3000 ÷ 4000 × 800 = 600 px. The result is 800 × 600 px, and the original 4:3 aspect ratio is preserved exactly.
- A 1200 × 800 image scaled to 50%. Both dimensions are halved: 1200 × 0.5 = 600 and 800 × 0.5 = 400. The result is 600 × 400 px.
- Entering one dimension keeps the pixel ratio. Because the missing side is always derived from the original proportions (height = original height ÷ original width × new width, or the reverse for height-only), the aspect ratio stays constant whenever you leave one field empty or use the Scale control.
So whether you shrink a wide landscape shot, a tall portrait, or a square avatar, the shape of the image remains true to the original as long as you let the tool calculate one of the dimensions for you.
Edge cases & limitations
- Upscaling softens the image. Enlarging creates brand-new pixels that weren't in the original, so the result looks softer or blurrier. No tool can invent detail that doesn't exist — for the sharpest output, resize down from your largest original.
- JPG drops transparency. The JPG format has no alpha channel, so transparent areas are flattened (usually to white or black). If you need to keep transparency, export as PNG, or WebP when the target platform supports it.
- File size depends on the format. JPG is usually the smallest for photographs; PNG is lossless but can be much larger on detailed photos; WebP often beats both while keeping good quality. The actual result depends on the image content.
- Extreme aspect ratios can distort when you force both dimensions. Entering a width and height that don't match the original ratio stretches the image. If that's not what you want, leave one field empty so the proportions are kept.
- Very large files use memory. The canvas lives in your browser's memory, so resizing an enormous image (for example, a 100+ megapixel panorama) on a low-spec device can be slow or, in the worst case, run out of memory.
Runs entirely in your browser — nothing is uploaded.
Frequently Asked Questions
Is this a real resize or just a preview?
It's a real resize. The tool decodes your image, redraws it at the new dimensions on an HTML5 canvas, and re-encodes it as a JPG, PNG, or WebP file. The Download button saves that actual resized file — the result you see is the file you get.
Can I keep the aspect ratio?
Yes. If you type only a width, the height is calculated automatically to match the original proportions, and vice versa. You can also type both width and height to force exact dimensions (which may stretch the image), or use the Scale field to resize by a percentage.
Which format should I choose?
Use JPG for photos and anything without transparency — it's the smallest file for photographs. Use PNG when you need transparency or a lossless result (for example, logos, screenshots, or diagrams). Use WebP when a platform supports it: it often beats both JPG and PNG on file size with similar quality.
Are my images uploaded anywhere?
No. Everything runs locally in your browser using the Canvas API — your image never leaves your device. This makes the tool safe for private photos, documents with sensitive content, or any file you don't want shared with a third-party service.
Does resizing reduce the image quality?
Only when you scale up. Shrinking an image keeps the detail that's already there and usually makes the file smaller, so there's effectively no quality loss. Enlarging an image creates new pixels that the browser has to guess at, which softens the result. If you're worried about sharpness, resize down from the largest original you have.
Which format is best for websites?
WebP is usually the best choice for modern sites: it compresses photos almost as well as JPG while also supporting transparency, and it generally produces a smaller file than both JPG and PNG at similar visual quality. The main catch is support — a very old browser or some photo-editing software may not open WebP, so JPG is the safer fallback for broad compatibility.
Does the tool preserve EXIF data and orientation?
No. Because the image is decoded and redrawn on a canvas, any EXIF metadata (camera settings, GPS location, capture date) is stripped from the output. Your browser does honor the embedded orientation tag when it renders the image, so the picture isn't turned sideways, but the metadata itself is not carried over to the downloaded file.
Can I crop the image instead of distorting it?
No — this tool only resizes, it doesn't crop. When you enter both a width and a height that don't match the original proportions, the image is stretched to fill them. If you want to remove parts of an image and keep the rest at its original shape, you'll need a separate crop step or tool first, then resize the cropped result here.