How to use it
- 1.Choose Pixels to set an exact width or height, or Percentage to scale every image by the same amount.
- 2.For pixels, type the width you need and leave the height empty: with “Keep aspect ratio” on, the height follows. Fill in both to fit images inside a box.
- 3.Drop your images on the page, paste one from the clipboard, or click “Choose images”. They are resized as soon as they’re added, and again whenever you change a setting.
- 4.Download the images one by one, or all of them as a ZIP file.
Pixels, file size and what resizing changes
An image’s size in pixels (for example 4032 × 3024 from a phone camera) decides how much detail it holds and how large it can be shown sharply. File size in kilobytes is a separate thing: it depends on the pixels, the format and the compression.
Halving the width and height leaves a quarter of the pixels, so the file usually shrinks to roughly a quarter too. That makes resizing the most effective way to make photos smaller for email, chat or a website. To shrink a file without changing its dimensions, use the image compressor instead.
Keep the aspect ratio, fit or stretch
With “Keep aspect ratio” on, images are never distorted. Give one side and the other follows; give both and each image is scaled to fit inside that box, so a landscape and a portrait photo both stay within, for example, 1920 × 1920. To get an exact shape such as a square, crop the image first with the image cropper.
With the ratio unlocked, images are stretched to exactly the width and height you type. That is only right when the target has the same proportions as the original; otherwise faces and circles look squashed.
Common sizes and resize quality
Full HD screens show 1920 × 1080 pixels, so 1920 wide is plenty for a full-screen photo on most websites. Instagram uses 1080 × 1080 for square posts and 1080 × 1350 for portrait ones, and link previews on social networks (Open Graph images) are 1200 × 630. For email attachments, 1280 to 1600 pixels on the longer side keeps photos sharp and small.
Large reductions are done in halving steps with high-quality smoothing, which keeps fine patterns and text from turning jagged. Enlarging can’t add detail that isn’t in the original: an image scaled up looks softer, which is why “Don’t enlarge smaller images” is on by default.
Questions and answers
Are my images uploaded?
No. Images are decoded, resized and saved by your browser on your own device. Nothing is sent to nestoo or anyone else, and the tool keeps working offline once the page has loaded.
Can I resize many images at once?
Yes. Add as many as you like: each one is resized with the same settings, one after another, and “Download all as ZIP” saves them in a single file. With “Keep aspect ratio” on, photos of different shapes each keep their own proportions.
Does resizing reduce the file size?
Yes, when you make an image smaller in pixels. Cutting the width and height in half typically leaves about a quarter of the file size. Lowering the quality or choosing WebP shrinks it further.
How do I change the DPI of an image?
DPI (or PPI) is only a hint for printing: it says how many pixels should go into one inch of paper. Screens ignore it, so what matters online is the pixel size. For print, divide the pixels by the DPI you need: a photo 3000 pixels wide prints 10 inches (25 cm) wide at 300 DPI.
What is the largest size I can resize to?
Up to 16384 pixels per side. In practice browsers limit how many pixels they can handle at once (Safari on iPhone and iPad stops at about 16.7 megapixels), so a very large result may fail on a phone. If it does, choose a smaller size or use a desktop browser.