Use Free Transform to resize an image with specific dimensions (Photoshop CS2/CS3/CS4/CS5)

You can resize your selections to an exact measurement using the Free Transform command. Just select the area you want resized. Then, press [command]T ([Ctrl]T in Windows) to access the Free Transform tool. Next, go to the tool Options bar and enter the appropriate measurements in the W (width) and H (height) text boxes, making sure to follow up the value with inches, pixels, etc. Then, press [enter] to apply your changes.