How image resizing actually works
An image is a grid of pixels. Resizing means making that grid smaller (or larger) and deciding what each new pixel should be based on the ones around it. Browsers do this with a built-in algorithm that's usually bilinear or bicubic — good enough for almost every use, and fast enough to run on thousands of images without breaking a sweat.
This tool draws your image onto an HTML <canvas> at the target size, then reads the canvas back out as a
new file. That's it. Nothing exotic, nothing server-side. Your browser already knows how to do it well.
When to set only width
Most of the time, you want a specific maximum width — an Instagram post, a blog hero, a product thumbnail. Leave the height blank: the tool keeps each image's aspect ratio and just scales to the width you gave it.
When to set both
If you need a specific canvas size — a profile banner, an app icon, a printed proof — enter both width and height. With "Lock aspect" on, the tool fits the image inside those bounds. Turn it off to stretch the image exactly to those bounds (rarely what you want, but sometimes necessary).
Choosing an output format
- Keep original — safest; best for mixed batches of photos and screenshots.
- JPEG — smallest file for photos; no transparency.
- WebP — smaller than both JPEG and PNG for most content. Supported everywhere since ~2020.
- PNG — lossless; use for logos, screenshots, anything with transparency.
Frequently asked
Does the tool upload my images?
No. Every resize happens on a canvas inside your browser tab. Nothing is sent to a server. You can disable Wi-Fi after the page loads and it still works.
What's the maximum input size?
Practically, around 80 MB per file. The limit isn't this tool — it's how much memory your browser will hand out for decoding a single image. Large ones will just take a second or two longer.
Can I upscale images?
Yes, but the result will look softer than the original — upscaling invents pixels. For small bumps (1.2× or so) it's fine. For big enlargements, use a dedicated AI upscaler instead.
Why do my PNGs come out larger than the original?
PNG compression is data-dependent. If you resize a simple PNG up, the output has more pixels to encode, so the file grows. Convert to WebP or JPEG for a smaller result.
Does this preserve EXIF?
No. Canvas-based resizing strips EXIF metadata, which is usually what you want — it removes GPS coordinates, camera serial numbers, and timestamps before you share a photo publicly.