Interior trim planning · Updated November 3, 2026
Door casing measured-length estimator
Estimate door casing footage and a footage-only stock-length minimum from measured head and leg pieces and an allowance you choose.
Enter measured head and leg piece lengths, the stock length you plan to buy and an allowance you choose. Use actual lengths for your doorway layout; this estimator does not derive the cuts.
Enter values and calculate.
For each doorway, measure the head and legs for the trim layout you plan to install. The allowance is your assumption, not a recommendation. The stock count is a footage-only lower bound; it is not a cut list. Miter geometry, joints, stock availability, cuts and reusable offcuts affect the amount to buy.
Sources and method
- The Home Depot: How to Trim a Doorway (reviewed November 3, 2026): for its miter-casing example, it describes marking a reveal, measuring between the vertical reveal lines for the head, and measuring each side piece. This estimator uses lengths you measure for your own layout; it does not encode the guide's cut method.
Method: multiply each entered piece length by its quantity and sum the footage. Multiply by 1 + your allowance percentage ÷ 100, then divide by selected stock length and round up. This total-footage count does not allocate pieces to boards or account for cut sequence, joints or offcut reuse.
How it works
Enter each head or leg piece's measured length in feet, including a label and optional quantity, then enter the stock length you plan to buy and any allowance you choose. The tool totals the measured lengths, applies your allowance and rounds up the total footage to stock-length equivalents. It does not calculate cut lengths, miters or an optimized board layout.
Good to know
Quick answer: how much door casing should I buy?
Measure the head and each leg piece you intend to install, total those lengths, apply your own allowance and divide by the selected stock length, rounding up. That gives a footage-only minimum; cut layout, joints, actual stock and reusable offcuts can change the quantity. Reviewed November 3, 2026.
What should I measure?
The Home Depot doorway guide describes measuring the vertical pieces and the head piece from the reveal lines for its miter-casing example. This estimator expects the lengths you measured for your own layout and does not calculate reveal, miter or other cut allowances.
What allowance should I use?
Choose an allowance based on your material, measurements and project cutting plan. The calculator does not recommend a percentage or assume a product yield.
Does this produce a cut list or exact board count?
No. It divides total adjusted footage by selected stock length and rounds up, so its stock count is a footage-only lower bound. It does not assign individual pieces to boards, optimize cuts or model offcut reuse.
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