About the Image Resizer
This image resizer changes the pixel dimensions of a photo, either by a percentage of its original size or to an exact width and height, and re-encodes it as JPEG, PNG or WebP when you are done. It runs entirely on the Canvas API built into your browser, so the file you upload is never transmitted anywhere — the resizing, the preview and the download all happen on your own device.
How to use the Image Resizer
- 1
Click the upload area and choose an image file, or drag one in.
- 2
Pick 'Percentage' for a quick scale, or 'Exact dimensions' to hit a specific width and height.
- 3
Leave 'Keep original aspect ratio' on unless you deliberately want to stretch or squash the image.
- 4
Choose an output format and quality, then download the result once the preview looks right.
What people use it for
Meeting a website's upload limit
Many platforms cap image dimensions or file size. Scale a photo down to fit before uploading it to a form, a listing or a CMS.
Preparing a profile picture or thumbnail
Resize a photo to the exact square or rectangle a platform asks for, such as a 512×512 avatar or a 1200×630 social share image.
Reducing page weight
A photo shot on a modern phone camera is often 4000px wide. Resizing to the dimensions it will actually display at cuts load time noticeably.
Resizing versus resampling
Every resize is really a resampling operation: the browser has to decide a new colour for each pixel in the output based on the pixels around the corresponding position in the source. Scaling down averages several source pixels into one, which is why shrinking rarely looks bad. Scaling up has to invent detail that was never captured, spreading existing pixels across more space, which is why enlarging a small image always looks softer than the original however good the algorithm is. The browser's built-in image smoothing handles this automatically; there is no setting to change it here because the default quality is already high for both directions.
Percentage versus exact dimensions
Percentage scaling is the safer default because it always preserves the aspect ratio, so a landscape photo stays landscape and nothing looks stretched. Exact dimensions matter when a form or platform demands a specific width and height in pixels — a passport photo size, a banner slot, a print size. With 'keep aspect ratio' on, the tool honours your width and derives the closest matching height, so if the two numbers you enter do not correspond to the same ratio as the source image, the height you typed is treated as a secondary target rather than an exact guarantee.
Tips
- For photos destined for the web, 1600-2000px on the longest side is usually more than enough resolution.
- Resize before you compress, not after — a smaller image compresses more efficiently at the same visual quality.
- If the output looks blurry, check you resized down rather than up; enlarging a small source image cannot add real detail.