Measure for a better fit.

A clear guide to interior and exterior storm windows. Explore the frame in 3D, then record your opening.

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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.

Horizontal slider window measuring guide

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.

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.

Arched and specialty-shaped storm windows

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 review

Plan the details before you order.

Mounting an exterior frame

Flanged exterior frames mount through the flange. Use fasteners suited to the mounting material: self-tapping screws for suitable metal, or a pilot hole and wood screw for wood. A separate drill for the bit and driver for the screw can make the work easier.

View installation guidance

A screen for a picture window

An external screen, including a solar screen, may be available for a fixed picture window. Perimeter hook-and-loop fastening or frame pins may be used depending on the frame and screen. Send the opening details so we can confirm the attachment and quote the screen separately.

Ask about a screen

Replacing a sash or panel

Send your window size and photos of the existing frame and sash. We can review the configuration and arrange a replacement sash quote. Confirm the required sash measurements with us before ordering a replacement.

Request a replacement sash

Not 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