Measure the largest window first to determine whether the square footage is over or under 12.5. If it is under, you don’t have to measure the rest 🙂
What you need to know before you start:
What is the square foot of each window? Measure the length and width of each window. Then multiply these two numbers to get the square footage.
Do the windows tilt in or turn for cleaning? Newer windows have latches that, when released, enable tilting or turning, so both sides can be cleaned from the inside.
Do they have grilles or divided lites? Divided lites are multiple panes of glass separated by wood or metal. Grilles are mounted over the surface of the glass.