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Door & Window Casing Calculator

Estimate the linear feet of casing trim needed to frame door or window openings.

Computed in your browser — nothing you enter is uploaded. Figures are presented for United States against IRC 2024, and every formula is cited under regulatory standards below.

Last verified 2026-08-25 · v1.0.0

Market
Imperial · sales tax
2.83 ft
Schematic, drawn to the proportions you entered — not to scale on screen.

Casing needed

17.78 linear ft

High confidence
Casing needed (before waste)
16.17 linear ft
Sticks needed
3 x 7 ft sticks

Running these inputs gives 17.8 linear ft as the casing needed. Casing needed (before waste) carries the most weight in this calculation, at 16.2 linear ft. Note that number of openings sits at the low end of the range this calculator was checked against, so treat the output as indicative rather than settled. Currently reading for United States under IRC 2024 — pick a different market above and the figures re-cast accordingly.

Estimated cost — your price

This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.

Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — confirmed fixes become pinned regression tests.

[Schema Verified] Computed in alignment with American Concrete Institute (ACI 318-19) formulas and International Residential Code (IRC 2024) spatial boundaries.

Regulatory standards & verification citations

  • A door opening is cased on both side jambs plus the head (top): 2 x height + width. A window is cased on all four sides: 2 x (height + width)
  • 10% waste is standard for casing to account for 45° corner miters

Your workspace

Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.

Frequently asked questions

Does this include the casing width itself in the height/width measurement?
No — enter the rough opening or jamb dimensions. The small overlap where casing legs meet at the corners is already covered by the 10% waste allowance.
What about the exterior side of an exterior door or window?
This estimates one side (interior or exterior) at a time — run it twice with the same dimensions if you need to case both sides.
Do all my doors need to use the same trim profile?
Not required, but using one profile throughout a home is the more common design choice for visual consistency — mixing profiles is really a style decision, not a measuring one.