Depending on the door, type of installation and your experience, it could take as little as 30 minutes or up to a few hours. First, remove the old screen door (if there is one) and take off the hinges. Measure the height and width of the door opening and cut the new storm door to size using a hacksaw or circular saw. If you're installing a new doorknob, drill holes for it now too. Next, attach the hinges to the storm door using screws. Open up the door and fit it into the opening in your house- make sure it's level. Screw in place from inside your house. Close and latch the door- if everything is installed properly, it should stay closed

It depends on the door, the installation, and your skill level. I would say a few hours. It's a fairly simple process. First, you need to measure the door opening to make sure you get a storm door that will fit. Next, you'll need to take off the old door if there is one and prep the surface for the new door. The most common way to attach a storm door is with screws or nails, so you'll need to drill holes and put in fasteners. Finally, you'll hang the storm door and test it for fit and function.