Horizontal slider windows
Record three full-span widths and three heights at the exterior mounting opening. Keep every reading and mark the smallest pair as fit checks, then note the operating side, handle clearance, and track depth.
Measure
How to Measure Storm Windows
Choose your measuring guide
What type of window are you measuring?
Pick the closest match first. The instructions and required measurements will change for that window type.
These guides record exterior storm-window openings—not final frame sizes.
Keep every width and height reading. The smallest opening width and height are fit checks for an opening that may be out of square; exterior does not mean using the largest height. Recessed blind-stop and face-mounted overlap installations require different factory allowances, so do not add, subtract, or round a measurement unless the manufacturer confirms the finished size.
Vertical-window measuring wizard
Step 1 of 6: Checklist
- Checklist
- Widths
- Heights
- Meeting rail
- Details & photos
- Confirm
Start here
For a vertical window, you need exactly seven measurements.
These are exterior storm windows. Record every opening reading separately. The wizard identifies the smallest width and height as fit checks; it does not calculate a finished frame size or overlap allowance.
Do not order yet.
Continue until every measurement and order detail is shown on the final confirmation screen.
Your seven-measurement checklist
- Top width
- Middle width
- Bottom width
- Left height
- Center height
- Right height
- Meeting-rail height
Guides by window type
Measuring a different type of window?
Keep the same rule: measure the opening where the storm-window frame will sit. The extra checks depend on the window shape and how it operates.
Fixed picture windows
Record three widths and three heights, keep the smallest pair as opening fit checks, and confirm that all four exterior mounting surfaces are flat and free of handles, alarms, or uneven trim.
Arches · round tops · trapezoids · custom shapes
Specialty windows require a shape review.
- 1. Photograph the entire opening straight-on.
- 2. Record the maximum overall width and height.
- 3. Record every straight side, spring line, angled corner, and diagonal shown on the supplied shape diagram.
- 4. Include one close-up photo of the mounting surface and one photo with the tape visible.
Do not order an arch, round top, trapezoid, or irregular shape from width and height alone. Send the photos and measurements for review first.
Submit a specialty opening for reviewNot sure about the mounting surface?
Stop before ordering. Send us photos of the full opening and close-ups of the top, sides, and sill.
Get measuring help