Dimensions and file size are different
Width and height describe the pixel grid. File size describes how many bytes the encoded image uses. Reducing dimensions often reduces file size because fewer pixels remain, but the format and image content also matter. The resizer reports both the new dimensions and resulting bytes.
One dimension controls the other
Keep proportions is enabled by default. When you change the width, the tool calculates the matching height from the original aspect ratio and shows it as an automatic value. This prevents a portrait from becoming unnaturally wide or a circle from turning into an oval. Turn the option off only when you deliberately need independent dimensions.
Choose dimensions for the destination
A small profile image does not need the pixel dimensions of a full-screen photograph. Start with the largest size at which the image will actually appear, then account for high-density displays if needed. Avoid repeatedly resizing an already reduced copy because every new encoding can lose detail.
Upscaling cannot restore detail
The tool can create a larger pixel grid, but it cannot recover information that was absent from the source. Enlarged images may look soft. For a larger result, return to the highest-quality original rather than scaling up a thumbnail.
The resize happens in the browser
Canvas performs the resize locally and creates a new downloadable image. The selected file is not uploaded. Animated images are treated as a single rendered frame, so use a dedicated animation editor when motion must be preserved.
Check where the result will be used
A social profile, website hero and printed page place different demands on an image. Confirm the required pixel dimensions before resizing, and leave enough room for any crop the destination may apply. On the web, provide explicit width and height attributes so the page can reserve space before the file loads. A resized image can reduce transfer cost, but it still needs a descriptive filename, appropriate alternative text and a format the target browser supports. When several sizes are needed, create each one from the original rather than from the smallest generated copy.
What the simple resizer avoids
It does not offer sharpening, print units, DPI editing or a batch queue. Those controls are useful in an image editor but add decisions that most quick web resizing tasks do not need. The output follows the original proportions and pixel content. Use a dedicated editor when colour management, detailed resampling control or production printing requirements matter.