How to Measure for Storm Windows
Storm window measurements depend on how the unit will be installed. The two most common options for this quote tool are Blindstop and Overlap. Window track measuring can also apply in some cases, but submit photos if you are unsure.
1. Choose the installation method first.
Blindstop installation sets the storm window into the blind stop area of the existing window. Overlap installation mounts the storm window over the exterior casing/trim area. Both are valid options, but they are measured differently.
2. Measuring for Blindstop width.
For Blindstop, measure the opening width in three places: top, middle, and bottom. Record the smallest width. The Blindstop top-view sketch shows the width taken between the blind stop surfaces.
3. Measuring for Overlap width.
For Overlap, measure the opening width and add the required overlap allowance. A common estimating rule is to add 1 inch to the measured opening width, but final sizing should be reviewed before ordering. The Overlap top-view sketch shows the storm window extending over the trim/casing area.
4. Measure height based on sill condition.
Measure height on the left and right side. Drop sill and standard sill conditions can change where the height should be taken. Use the sill height sketch to compare drop sill, standard sill, and outside mount conditions.
5. For Hung storm windows, measure the meeting rail.
For Hung units, measure the storm window meeting rail location so it can align with the existing window meeting rail. Use the same installation reference you used for sizing. For Blindstop, measure from the top of the storm-window opening to the middle of where the existing window panels meet. For Overlap, measure from the intended top edge of the storm frame to the middle of where the existing window panels meet.
6. Take clear photos.
Include straight-on exterior photos and close-up photos of the trim, sill, blind stop, casing, and existing window frame. Photos help confirm whether Blindstop or Overlap is the better method.
7. Create a simple window schedule.
For each line, list window type, installation method, width, height, quantity, and meeting rail location for Hung units. Example: “Line 1 - Hung - Blindstop - 30 x 62 - Qty 8 - Meeting Rail 31 inches.” For Hinged units, include the hinged side as Long or Short.
8. Submit for formal review.
The online estimator is for budgeting only. A formal quote should confirm sizing method, configuration, color, glass, screens, freight, taxes, and any project-specific additions before ordering.
Only sketch references are linked above. Installation photos with hands are intentionally not included.