Four ways to say how big
- Pixels. Type a width, a height, or both, as whole numbers from 1 to 100000. A box with 0, a negative number or a fraction turns red, says why, and the big button waits until it is fixed. With one picture and the lock on, a number typed in one box fills in the other from the shape of the picture. With several pictures the lock stays out of the way and each box keeps what you typed: a width alone gives every picture that width and each keeps its own shape, and when you fill both boxes every picture is fitted to that box. Clear one box to set only a width or only a height.
- Percent. 50 percent halves both sides, which leaves a quarter of the pixels. Good for quick reductions where no exact size is needed.
- Side. Set the longest side (nothing longer than 1600 px) or the shortest side (nothing shorter than 1080 px). This is the most useful setting for a batch, because landscape, portrait and square pictures all end up sensible: a 4000 by 3000 photo becomes 1600 by 1200, a 3000 by 4000 one becomes 1200 by 1600.
- Presets. Web sizes (4K at 3840, 2560, Full HD at 1920, HD at 1280, 800 and 640), thumbnails (150, 300, 600), email (800) and square avatars (64, 128, 256, 512). Sizes for social networks are in the social image resizer, so they are not repeated here.
The line above the settings shows what will happen to the first picture, for example "4000 × 3000 px becomes 1600 × 1200 px, 1.9 MP", and every file in the list shows its own result before you press anything.
Fit, fill, stretch and pad
When you type both a width and a height, the picture and the box can have different shapes. You choose what happens, and for fill, stretch and pad the two numbers are used exactly as typed (the lock does not change them):
- Fit inside keeps the whole picture and its shape. The picture is as large as it can be without going over either number.
- Fill and crop fills the box exactly and cuts off what sticks out. You choose which part stays: the middle, the top, the bottom, the left or the right. Good for square thumbnails.
- Stretch to exact gives exactly the size you typed and changes the shape of the picture to get there.
- Pad to exact keeps the whole picture and fills the rest of the box with a colour, or leaves it transparent for PNG, WebP and AVIF.
Sizes are whole pixels, rounded to the nearest and never below 1. The side you set is exact and the other follows within half a pixel, so a 4001 by 2999 photo set to 1600 wide becomes 1600 by 1199. A percentage works through the longer side, so a very thin picture keeps its shape.
Sharp results, and no enlarging by accident
Shrinking uses Lanczos resampling, the method good image editors use for reductions. It averages the colour values as they are stored in the file, so a white background stays pure white and thin dark lines, such as small text in a screenshot, keep their weight. We checked it against the Lanczos filter of Pillow, the Python imaging library. On black text shrunk to a third of its size, the darkest tenth of the pixels averaged 114.2 out of 255 here and 114.5 in Pillow, and on photos, a scan and text the two results differed by under half a level on average. Transparency is handled separately, so a cut-out does not get a dark rim.
Sharpen slightly after shrinking is off by default. It adds a light sharpening that never goes past the brightest or darkest neighbouring pixel, so it creates no halos, and it is used only on pictures that were made smaller. How much it changes depends on the picture. On a 3072 by 2048 photo shrunk to 1000 pixels wide it changed about 6 in 10 pixels, by 3 levels out of 255 on average among those, and by at most 40 at the sharpest edges. On black text shrunk to a third of its size it changed about 2 in 10 pixels, by 12 levels on average, and by at most 52.
Making a picture bigger cannot add detail that is not there, so Allow enlarging is off by default. A picture that is already smaller than your target keeps its size, and the list and the result say so. With stretch, each side is held at the original size. With fill, the box is made smaller in the same shape, as large as the picture allows. With pad, the picture sits in the middle of the box at its own size. SVG files are the exception: they are vector pictures, so they are drawn at the size you ask for instead of being enlarged afterwards.
Formats, metadata and limits
- Save as. The default keeps each file in its own format: JPG, PNG, WebP and AVIF stay as they are. TIFF and HEIC photos are saved as JPG, because a PNG of a photo is many times bigger, and GIF, BMP, SVG and ICO files are saved as PNG. Or choose one format for everything.
- Quality. JPG starts at 90, WebP at 85 and AVIF at 65 (the smallest files, but slow). PNG is lossless: the pixels are saved exactly, and a lossless optimiser shrinks the file, except above 16 megapixels where it is skipped to keep things moving.
- Metadata. Removed by default: the new files carry no camera details, date, GPS location or colour profile, and colours are converted to sRGB. Choose Keep to copy the EXIF block from JPG, PNG and WebP originals into JPG, PNG and WebP results, with the rotation reset and the picture size updated. The result reports what was really kept.
- Sideways photos. Phones often store a photo sideways with a note that says how to turn it. The note is applied, so results come out the right way up. An animated GIF or WebP is resized from its first frame only, and the list tells you.
- SVG and TIFF. An SVG is drawn at the size you ask for, also when it embeds HTML with foreignObject, and nothing it points to on the internet is loaded while it is drawn. A TIFF with several pages is opened at its largest page, and the list shows the size of that page. A TIFF that stores red, green and blue in separate planes is read correctly.
- Pictures that need no change. A picture that already has the size you asked for, in its own format, is handed back as it is, not saved again, so it cannot lose quality or grow. Camera details, date and location are taken out without touching the picture when Metadata is on Remove, and the colour profile and the rotation note stay. Choose Keep and the file comes back unchanged. The list marks these files "left as it is".
Pictures up to 100 megapixels are accepted, for example 10000 by 10000 pixels. Phones and older laptops may run out of memory sooner, and that is reported in plain words. Large pictures in a batch are resized one at a time while small ones run side by side, and you can cancel at any time: finished files keep their results.