How to resize an image to exact dimensions — and why it matters
Every platform you upload to has a preferred image size. Instagram's square posts are 1080×1080 pixels. Twitter headers want 1500×500. Facebook covers are 820×312. Email signatures look cleanest at 600px wide. Upload the wrong size and you get stretched, cropped, or blurry images — the platform rescales them however it wants. Resizing before you upload means you stay in control.
This tool lets you set an exact width, exact height, or both. You can work in pixels or scale by percentage. The aspect ratio lock calculates the missing dimension automatically — enter 1080 for the width and the height fills in to match your original proportions. No distortion, no guessing.
What happens to file size when you resize an image?
Smaller dimensions almost always mean a smaller file. A 4000×3000px photo from a modern phone can easily sit at 6–10 MB. Resize it to 1200×900px and you'll typically land somewhere between 200–500 KB — a 90%+ reduction, just from changing the dimensions. That's before any compression is applied.
If you need to hit a specific file size target rather than a specific pixel count, compress the image after resizing. Compression adjusts quality to shrink the file further without touching the dimensions. The two tools work well together. If your target is something specific like 20 KB — common for government form uploads — use the dedicated resize to 20KB tool which handles the math automatically.
One thing to know: resizing up (making an image larger than its original dimensions) doesn't add real detail. Standard canvas scaling interpolates pixels, which softens the image. For a 1200×800 photo that needs to become 3000×2000, you'll notice blur. That's a physics problem, not a tool problem. For genuine upscaling, a dedicated AI upscaler does a better job by hallucinating plausible detail.
Aspect ratio lock — why you should almost always leave it on
The aspect ratio lock is the chain icon in the options bar. When it's active, changing the width recalculates the height proportionally (and vice versa). This keeps your image looking like your image. Turn it off only when you deliberately want to stretch or squish — fitting a square photo into a widescreen banner slot, for example.
If you're resizing for a specific platform preset that requires both dimensions, you'll need to disable the lock and set both values. Just be prepared for the image to look slightly different if the original ratio doesn't match the target ratio. Cropping to the correct ratio first — using the crop tool — then resizing is the cleaner workflow for platform-specific sizes.
Common image sizes for social media and web
Here are the dimensions people search for most often. Instagram feed posts: 1080×1080 (square) or 1080×1350 (portrait). Instagram stories and Reels: 1080×1920. Twitter/X profile header: 1500×500. Facebook cover photo: 820×312. LinkedIn cover: 1584×396. YouTube thumbnail: 1280×720. General blog images: 1200×630 is a safe default that also works as an Open Graph image for link previews.
For product photography on e-commerce sites, 1000×1000 is a common requirement — most platforms zoom-on-hover features need at least 1000px on the long edge to work well. For email signature images, keep width at or below 600px so they don't overflow on smaller screens. A logo at 200×60 pixels is typical; anything larger and it dominates the signature.
Batch resizing — resize multiple images to the same size
Drop multiple images at once and they all get resized to whatever dimensions you've set. Select 50 photos from a shoot, enter 1200×800, click Resize Images — all 50 come back at 1200×800. Download them as a single ZIP file. The original files aren't modified; everything runs in your browser and the originals stay exactly as they were.
Because the tool is 100% in-browser, there's no upload queue, no waiting for a server to process, and no privacy concern. The Canvas API handles the resizing locally — it's the same technology browsers use to draw graphics and games. Your images never touch a server.
Percentage scaling vs. pixel dimensions
Switch the mode to Percentage and you get a scale slider instead of pixel inputs. Set it to 50% and every image comes out at half its original dimensions. Set it to 200% and everything doubles (with the caveats about upscaling mentioned above). This mode is useful when you have a batch of differently-sized images and you want to reduce them all by the same factor rather than targeting a fixed pixel count. A folder of mixed-size product photos scaled to 40% will all be proportionally smaller, preserving their individual ratios.