How to Resize an Image to Exact Pixel Dimensions

To resize an image, set a target width or height and let the other side scale to match, or set both to force an exact size. The Resize Image tool does this for free in your browser — set Width px and/or Height px, pick an output format, and download the result. Nothing is uploaded; the resizing happens entirely on your device.

This guide covers the two ways the tool resizes images, a worked example, and the details that trip people up — like aspect ratio and transparency.

What this tool actually does

Resize Image changes an image's pixel dimensions. It defaults to Width px (0 = auto) set to 1,200 and Height px (0 = auto) set to 0, which means: scale to 1,200 px wide and calculate the height automatically. You can also pick an output Format (Same as original, PNG, JPG or WebP) and a Quality slider (0.1–1, default 0.9) that controls JPG/WebP compression — it has no effect on PNG, which is always lossless.

Unlike a compressor, this tool isn't trying to shrink the file — it's for getting an image to a specific pixel size, whether that's bigger, smaller, or just a different shape.

How to resize an image with Toolbench

1. Open Resize Image.
2. Drop in an image, paste one from your clipboard, or click to choose a file.
3. Set Width px and/or Height px:
   • Fill in just one and leave the other at 0 to scale proportionally.
   • Fill in both to force an exact size (see the aspect-ratio note below).
   • Leave both at 0 to keep the original dimensions — useful if you only want to change the format.
4. Choose a Format, or leave it as "Same as original."
5. Adjust Quality if you chose JPG or WebP.
6. Check the result line for the new dimensions and file size, then download it — or sign in to save it to your Gallery.

Worked example

Start with a 3,000 × 2,000 px photo (a 3:2 ratio):

• Width = 1,200, Height = 0: the tool calculates the height to match — 2,000 × 1,200 ÷ 3,000 = 800. Result: 1,200 × 800, same ratio as the original.
• Height = 600, Width = 0: the tool calculates the width — 3,000 × 600 ÷ 2,000 = 900. Result: 900 × 600.
• Width = 1,200, Height = 1,200: both are set, so the tool resizes to exactly 1,200 × 1,200 — a square — which stretches the original 3:2 photo rather than cropping or padding it.

Aspect ratio: the one setting to watch

This is the detail that catches people out: the tool only preserves the original aspect ratio when you leave one of the two dimension fields at 0. If you type a value into both Width and Height, it resizes to exactly those pixels, even if that changes the picture's proportions. For a square crop that doesn't distort the image, use Crop Image instead — it trims to a ratio rather than stretching to one.

Format and quality notes

• "Same as original" keeps the input's format if it's PNG, JPG or WebP. For any other format your browser can decode, the output falls back to PNG.
• Quality only matters for JPG and WebP. PNG is lossless, so the slider doesn't change a PNG's size or look.
• Transparency and JPG don't mix. JPG has no alpha channel, so resizing a transparent PNG and saving it as JPG fills the transparent areas with white. Keep the format as PNG or WebP to preserve transparency.
• Dimensions are capped at 8,000 px on the longest side, in either direction.

Resize vs. compress vs. crop

Need	Use
A specific pixel width or height	Resize Image
A smaller file size for the web	Compress Image
A specific aspect ratio (1:1, 16:9, 4:5…) without stretching	Crop Image
Exact sizes for a specific platform (Instagram, X, Open Graph…)	Social Media Resizer
A different file format, same dimensions	Convert Image Format

Common mistakes

• Typing both Width and Height on a photo that isn't already that ratio — the image stretches. Leave one at 0 unless you specifically want an exact, possibly distorted, size.
• Expecting a smaller file just from resizing. Fewer pixels usually means a smaller file, but if you need the smallest possible file for the web, use Compress Image, which is tuned for that with a quality default of 70% and WebP output.
• Saving a transparent PNG as JPG and being surprised the background turned white.

Related tools

• Compress Image — shrink file size with format and quality presets tuned for the web.
• Crop Image — trim to a ratio instead of stretching to one.
• Convert Image Format — switch between PNG, JPG and WebP.
• Social Media Resizer — exact sizes for Open Graph, Instagram, X, LinkedIn and YouTube.

Frequently asked questions

Will resizing distort my image?

Only if you set both Width and Height to values that don't match the original's proportions. Leave one of the two fields at 0 and the tool calculates it from the original aspect ratio, so the picture doesn't stretch.

Does resizing an image make the file smaller?

Usually, since there are fewer pixels to store, but it isn't guaranteed and resizing alone isn't optimized for file size the way a dedicated compressor is. For the smallest file, use Compress Image.

What's the largest size I can resize to?

Each side is capped at 8,000 px.

Can I resize a transparent PNG and keep the transparency?

Yes, if you keep the output format as PNG or WebP. Saving as JPG fills transparent areas with white, since JPG doesn't support transparency.

Is my image uploaded anywhere when I resize it?

No. The resize happens in your browser on your own device. The only way a copy is stored elsewhere is if you sign in and choose to save the result to your Gallery.