Two ways to resize
By percentage scales the whole image by the same factor, from 5% to 200% in steps of 5, starting at 50%. It's the quickest choice for 'make these photos smaller' and works on a whole batch of different-sized images at once.
By pixels lets you type a width, a height or both. With Keep aspect ratio on, the image is scaled to fit inside that box without distortion, and a field left empty doesn't constrain that side: type only a width of 1200 and every image becomes 1200 pixels wide, whatever its height. With Keep aspect ratio off, the image is stretched to exactly the width and height you enter.
What image size do I need?
Some targets that come up again and again:
- Website and blog images: 1200–1600 px wide covers most layouts, including high-resolution screens.
- Instagram: 1080 px wide (1080×1080 square, 1080×1350 portrait).
- Facebook and LinkedIn link and post images: about 1200×630.
- Email: 600–800 px wide displays well in most email clients.
- Passport, visa and exam forms: these often specify exact pixels (for example 600×600). Use By pixels, and turn Keep aspect ratio off only if the photo is already the right shape.
Why smaller images matter
A 12-megapixel phone photo is about 4000×3000 pixels, several times more than any screen shows at once. Resizing to the size you actually need cuts the file size roughly with the pixel count: halving width and height leaves a quarter of the pixels. Pages load faster, emails send faster, and upload limits stop being a problem.
Enlarging is possible up to 200%, but it can't invent detail. The image gets bigger and smoother, not sharper. Use it to meet a minimum-size requirement, not to rescue a small photo.
Format and quality
Resized JPEGs stay JPEG and WebP stays WebP, saved at 92% quality, high enough that the only visible change is the size. PNGs stay PNG, lossless, with transparency kept. Other formats, such as HEIC from an iPhone, are saved as PNG. Scaling uses the browser's high-quality smoothing, so downsized photos stay crisp rather than jagged.
Batches and privacy
Add several images and they're all resized with the same settings, ready to download one at a time or together as a ZIP. Resizing happens in your browser, so nothing is uploaded, and the output carries no EXIF metadata such as location. Phone photos are turned upright before resizing.
What's the difference between pixels and DPI for printing?
Printed size depends on pixels and print resolution together. Photo labs print at about 300 dots per inch, so a 4×6 inch print needs 1200×1800 pixels, an 8×10 needs 2400×3000, and a 2×2 inch passport photo needs 600×600. The 'DPI' or 'PPI' number stored inside an image file doesn't change its pixels or its quality. It's only a hint for printing, and many forms that ask for '300 DPI' really care about the pixel dimensions.
So when a print shop or form gives inches and DPI, multiply them to get pixels and use By pixels here.
Can I resize images with apps I already have?
Windows 11's Photos app can resize a single image (open it, choose the ••• menu, then Resize image), and on a Mac, Preview does it via Tools → Adjust Size. They're fine for one photo at a time. This tool resizes many images in one go with the same rule, such as every image 1200 pixels wide whatever its original size, which is what blogs, shops and photo uploads usually need.
Batch results and file names
Each resized image keeps its original name, with the extension changed only if the format changed (for example HEIC photos saved as PNG). When you download everything as a ZIP, files that would share a name get -2, -3 and so on added, so nothing is overwritten. The list shows each new size, so you can check at a glance that a batch of different photos all came out at the width you asked for. If one image needs different settings, such as a banner that should be wider than the rest, resize it on its own afterwards: changing a setting clears the previous results, so each batch always reflects the settings shown.