If the door is 7 tall frame the opening 7 1 5.
Frame out garage door.
They are also rot resistant which means it will take decades to breakdown.
Frame the rough opening to 3 inches wider than the garage door size you have selected.
Woodworkers prefer it because they are lightweight effortless to cut stain and hit a nail into.
Pine is an excellent choice for a garage door frame.
The pale yellowish look of pine also gives it an extra edge and something to consider.
If you are installing a 9 wide door the opening will be 9 3 wide.