A simple template can take the hassle out of measuring, marking and drilling holes to mount and hang curtains in your home. This way you measure and set up your template, and then move the template between windows -- measure once, then hang as many times as you need. Image from edenpictures.
A template makes sure your curtains and their curtain rod are at the same height and width for every similar window in your home. Measure where you want your curtain rod to be for one window, then cut out two pieces of cardboard that are the same distance away from the edge of the window frame as your measurements. Tap the two pieces together to form a 90 degree corner, which you can now use to mark where your curtain rod should go on every similar window around your house. Easy, quick and you don't have to re-measure for each window.
How to Hang Curtains: Do's and Don'ts [Apartment Therapy]