Sometimes you’ll take an exceptional landscape photograph only to discover later that the horizon isn’t level. It can often be a challenge leveling the horizon, but there is an easy way to do it using virtually any image editing program:

Simply make your best-guess adjustment with the “Rotate Image” tool, then click on the “Crop” tool and use one of the horizontal dotted or dashed edges of the crop box as a guide. This will let you know instantly if the horizon is now level or not. If not, click cancel and try another “Rotate” setting, then check the horizon again using the crop line. When the horizon and the horizontal crop line are more or less parallel, you’ll know you have a level horizon! (Note: Don’t forget to cancel the “Crop” function.)