Image Resizer
Resize images to any dimension
100% free. Runs entirely in your browser - your files and data never leave your device and nothing is uploaded to any server.
Thumbnail selected — upload an image to apply it.
Drag & drop files here
or browse to upload
Supports PNG, JPG, WebP up to 20MB
Processed in your browser - your file never leaves this device.
About this tool
A 300 by 300 thumbnail is the workhorse of web galleries, product grids, CMS listings and email newsletters - small enough that dozens load quickly, big enough to recognise the subject. Resizing thumbnails properly instead of letting the browser shrink full-size photos is one of the easiest page-speed wins. This page crops to that small square, light enough that a page full of them still loads quickly.
How to use this tool
- Add the imageDrop in a product photo, portfolio piece or article image.
- Crop to the subjectZoom in so the product or face fills most of the small square.
- Export light filesSave as WebP or JPG for the smallest file and upload it to your grid or newsletter.
Why real thumbnails beat scaled-down photos
A 4000-pixel photo shown at 300 pixels still downloads in full, wasting bandwidth and slowing the page. A real thumbnail can be a tiny fraction of the size. For sharp results on high-density screens, some sites serve a 600 x 600 version to Retina devices while keeping 300 x 300 as the base.
Thumbnails and page speed
Letting the browser shrink full-size photos into small thumbnails means every visitor downloads megabytes they never see. Resizing them to 300 x 300 first can cut the weight of a product grid or gallery page dramatically, which speeds up loading and helps Core Web Vitals.
Export thumbnails as WebP or compressed JPG, and use consistent crops - centred products or faces - so a grid of thumbnails looks tidy.
Key features
- Real thumbnails instead of full-size photos shrunk by the browser.
- Faster product grids, galleries and email newsletters.
Common uses
- Product grids.
- Blog and portfolio listings.
- Email newsletter images.
Tips for better results
- Crop to the subject before resizing.
- Compress after resizing.
- Consider a 2x version for Retina.
Mistakes to avoid
- Using full-size photos as thumbnails.
- Inconsistent crops across a grid.
Frequently asked questions
300 x 300 pixels is common; use 600 x 600 for high-density screens.
Yes - they avoid downloading full-size images for small previews.
WebP is usually smaller; JPG is universally supported.
Small enough that a page full of them still loads quickly, which is the only real constraint on a thumbnail.
Drop it onto this page. The Thumbnail preset is already selected, so it resizes straight to 300 x 300 pixels and shows the crop before you download.