Does this resize the actual image file?

No — it calculates the target pixel dimensions only. It is a planning tool for figuring out the right width and height before you export from an editor or CDN.

How does it keep the aspect ratio?

When you set a target width it computes height = width ÷ (original width ÷ original height), and the reverse when you set a target height, so the image never stretches.

Why are the results rounded?

Pixel dimensions must be whole numbers, so each computed width and height is rounded to the nearest integer. This can shift the final aspect ratio by a fraction of a pixel, which is invisible in practice.

Can I scale up as well as down?

Yes. A percentage above 100 (for example 200) doubles the dimensions, and a target larger than the original enlarges the image. Remember that enlarging beyond the source resolution will look soft when actually rendered.

What is the difference between scaling by width and by height?

Set a target width and the tool solves the height from the original ratio; set a target height and it solves the width. Both keep the image proportional — you just choose which side to fix.

Is anything uploaded?

No — it is pure arithmetic that runs entirely in your browser.

Image Dimension Scaler

Image dimension scaler

Plan a proportional resize without ever stretching an image. This is a planning tool for designers and developers who need the exact pixel width and height before exporting from an editor, building a responsive srcset, or configuring a CDN transform.

How it works

First it computes the original aspect ratio as ratio = width ÷ height. Then, depending on the mode you choose:

Percentage: both sides are multiplied by the factor, e.g. outW = round(width × percent/100) and the same for height.
Target width: you set the width; height is solved as round(width ÷ ratio).
Target height: you set the height; width is solved as round(height × ratio).

Each result is rounded to a whole pixel, so the ratio is preserved to within a sub-pixel.

Example

Starting from a 1920×1080 image (16:9 ratio):

Mode	Input	Result
Percentage	50%	960 × 540
Target width	1280	1280 × 720
Target height	360	640 × 360

Everything is calculated in your browser; no image is uploaded.