The Width and Height values are in pixels by default, but you can choose different units of measurement by clicking the “Dimensions” drop-down above near the top of the window.
If you want to specify both the height and the width without one changing the other, click the small link icon to the left of the Width and Height blanks to unlink the two measurements. [1] X Research source If you don’t want to specify the size in pixels, you can select Percent from the menus next to the Height and Width values. Then you can choose to grow or shrink the image size by a percentage of the original size. For example, if the width of the image is 2200 px wide, changing the Width value to 50% will decrease the width to 1400 px. Changing it to 200% would increase the size to 4400 px. If the image has layers with applied styles, click the gear icon at the top-right corner of the Image Size window and select Scale Styles to scale the effects in the resized image. [2] X Research source
To save the new image, click the File menu and select Save. The original size of the image is still saved to the image’s original location.
