How to Measure for Andersen Full-Frame Replacement Windows

Drill a 1/4-inch "access hole" in the top left and top right sides of the window frame at the top of the window. If the window is an old-style "pocket window" with weights and pulleys, cut the rope that runs through the pulleys and use the pulley opening instead.

Insert a stiff wire into the hole at the left of the window frame until the wire comes in contact with the side of the window opening in the wall. Slide your fingers along the wire remaining outside the frame until they come in contact with the window frame.

Remove the wire without moving your fingers: The wire serves as a "depth gauge" and your fingers mark the depth to which the wire went into the hole. Use a measuring tape to measure the distance from the end of the wire to your fingers and record this measurement. Repeat this process on the right side of the window.

Measure the width of the window at the top of the window frame, inside the jambs. Add this measurement to the measurements taken with the wire depth gauge.

Drill a 1/4-inch hole in the bottom center of the window jamb at the window sill, opening the widow sashes as needed. Insert the wire depth gauge into the hole until it makes contact with the bottom of the window opening. Slide your fingers down the wire to the sill and keep them in place on the wire. Remove the wire from the hole and measure the distance from the end of the wire to your fingers. Record this distance. Repeat this process at the top center of the window jamb.

Measure the height of the window frame from top to bottom, inside the jambs. Add this measurement to the measurements taken with the wire depth gauge at the top and bottom of the window frame and record the result.

Provide the total height and width measurement to the Andersen Windows dealer.