How do I shrink an image by 50 percent, and how much smaller will the file get?
The tool works in pixels, so type half of the current width with the ratio lock on and the height follows. Halving both sides leaves only a quarter of the pixels, so the file usually gets much lighter, but the exact saving depends on the picture, the format and the quality. That is why the tool shows the measured size before you download.
Half, in pixels
There is no percentage field in the resizer, and that is deliberate: platforms and forms ask for a pixel number in the end. When you choose the image, its original width and height appear in the two fields, so you divide the width by two, type it, and the ratio lock does the rest.
A phone photo of 4032 × 3024 px, about 12.19 megapixels.
Type a width of 2016 and the height becomes 1512 on its own.
The result is 2016 × 1512, about 3.05 megapixels: exactly a quarter of the pixels.
If the width is an odd number, do not worry: the tool rounds the height to the nearest whole pixel, a one pixel difference no eye can see.
Why a quarter and not a half
An image is an area, and area is width times height. Halve the width and halve the height, and the area becomes a quarter of what it was. This surprises many people: 'half size' really means the picture lost three quarters of its pixels. The reverse holds too: doubling both sides means four times the pixels.
And the file size?
File size does not follow the pixel count precisely. A picture full of detail, like patterned fabric, behaves differently from a product on a white backdrop. Format and quality matter as well: saving a photograph as PNG can give a heavy file even after shrinking, and the resizer's default quality is 90.
So do not rely on an estimate. Once you type the new width, the results table shows the original and new file sizes side by side, and that is the real figure. If it is not enough, lower the quality to 80, say, and watch the number change, or use the Image compressor for a set of photos.
The steps
- Open the Image resizer, choose the image and note the number in the width field.
- Make sure the ratio lock is on and type half that width.
- Choose JPEG or WebP for photographs, and keep quality at 90 or lower it a little.
- Compare the two sizes in the table, then download.
Common questions
Can I shrink to a quarter or a third the same way?
Yes. Divide the width by the factor you want and type the result; the height follows. The pixel count becomes the square of the factor: a third leaves one ninth of the pixels.
Does halving make the picture less sharp?
It stays sharp at its new size, but the fine detail that was removed does not come back if you enlarge it later, so keep the original.