How to measure for a magnetic screen door

Most magnetic screen returns start as a measuring mistake. The listing is not wrong so much as the tape measure was on the wrong part of the door. Spend five minutes on the opening and you can ignore half the size names in a search result.

What you need

• A steel tape. A cloth tape stretches.
• A pencil and the back of an envelope. Phone notes are fine if you label top, middle, and bottom.
• A step stool if the top stop is above eye level. Guessing the last inch is how screens drag.

Width

1. Find the surface the tape will stick to. That is usually the flat face of the side stop, just inside the casing.
2. Measure across the opening at the top, the middle, and about two inches above the floor.
3. Keep the smallest of the three. A belly in the middle is the number the magnets have to live with.

If one side is brick molding and the other is a flat board, measure to the place you can actually stick a strip, not to the outermost brick. Sliding doors are a special case: decide whether you are screening one panel or the whole clear opening when the panel is open. Those are different widths. See sliding doors.

Height

1. Hook the tape on the threshold, or on the finished floor if people walk through with no raised sill.
2. Measure to the underside of the top stop, not to the top of the decorative trim.
3. Repeat on the left and the right. Keep the shorter one.

A screen that is too long bunches on the threshold and the magnets walk away from each other. A screen that is short leaves a beetle highway. Listings that include a weighted hem, such as MAGZO 36 × 96 screen (Amazon, opens in a new tab), still need the hem to reach the sill. Weight does not add inches.

Match a fit line, not a vibe

Once you have a width and a height, open a listing and find the sentence that says "fits." For AUGO fiberglass screen (Amazon, opens in a new tab) that sentence is 36 × 82 in, while the mesh itself is 38 × 83 in. For AUGO polyester 38 × 81 screen (Amazon, opens in a new tab) it is 36 × 80 with a 38 × 81 mesh. For AUGO 34 × 81 screen (Amazon, opens in a new tab) it is 32 × 80 with a 34 × 81 mesh. If your opening is 36 wide and 80 tall, the 82-inch fiberglass door is the wrong height even though it is our overall pick.

When the listing argues with itself

AUGO 74 × 81 screen (Amazon, opens in a new tab) is titled 74 × 81 in and the material field says polyester. We did not get a separate "fits door size" sentence in the text we saved, so do not do the minus-two-inches math from the other AUGO pages unless the live bullets say to. IKSTAR polyester screen (Amazon, opens in a new tab) is the cautionary example: title 38 × 82, technical field "fit door size to 38 × 81." If those two numbers are both on the page when you look, believe your tape and the more conservative fit.

RV doors add a third number, the frame outside the opening. EJYTRVT RV screen (Amazon, opens in a new tab) says a 33 × 80 opening and frames up to 30 × 79 excluding the frame. Falafa RV screen (Amazon, opens in a new tab) says frames up to 30 × 73, and one specification line looked like the height and width were swapped. If you cannot reconcile the page with the tape, do not buy it to "make it work."

A worksheet you can copy

• Top width, middle width, bottom width. Circle the smallest.
• Left height, right height. Circle the shortest.
• Trim material: wood, painted wood, vinyl, aluminum, tile, brick.
• Will you use pins? Only wood gets a yes.
• One panel or the whole opening?
• Pets that claw, or only pets that push?

Take that note to the buying guide and then to the install page. The order matters. Hanging a screen you have not measured is how the tape ends up doing a job it cannot do.