How to Measure for a New Commercial Door

Getting numbers wrong wastes money. Accurate door measurement keeps your project on schedule and avoids rework. A well-documented industry study found that 48% of all rework in the United States construction industry was caused by poor data and miscommunication, proving that careful door measurement upfront matters.

Don't start without the basics:

• Tape measure

• Level

• Pen and paper (or your phone)

• Ladder or step stool

If you're replacing a frame, have a flashlight to inspect the edges and hardware. Many contractors also use manufacturer forms to stay organized. Door frames and frame packages that align with standard measurements require exact dimensions, which is why getting these measurements right from the start matters

If you're replacing a door in the current frame, use this sequence:

• Door width – Measure across the top, middle, and bottom. Write down the smallest.

• Door height – Measure both sides from the top edge to the floor. Record the smallest.

• Door thickness – Most commercial doors are 1-3/4 inches thick. Confirm before ordering.

• Hinge locations – Measure from the top of the frame to each hinge's top (the "top-to-top" method). Note hinge size.

• Strike location and backset – Measure from the top of the frame to the strike opening. Standard backset is 2-3/4 inches.

• Handing – Stand with your back to the hinges. If the door opens to your left, it's left-handed; if to the right, it's right-handed.

The Steel Door Institute's field measuring form provides the exact locations where measurements should be taken, eliminating the guesswork leading to costly ordering mistakes.

When starting with a framed opening, measure the rough opening carefully:

• Width – Stud to stud at the top, middle, and bottom.

• Height – Floor to header on both sides.

• Depth (throat or jamb depth) – This equals the wall thickness.

A rough opening is typically 2 inches wider and 2-1/2 inches taller than the door slab size. For example, a 36" x 84" door needs a 38" x 86-1/2" opening.

And don't forget code requirements. According to the ADA Standards, every commercial entry must provide at least 32 inches of clear width when the door is open to 90°.

If you're planning a steel package, commercial steel doors are manufactured to fit standard rough openings, but only when those openings are measured correctly.

Measurements aren't just about fit—they're about passing inspection. If you miss these numbers, you'll face delays or rework during approval.

ADA: 32-inch minimum clear width at 90°.

NFPA 80 (fire-rated doors): 1/8-inch clearance at jambs and head; 3/4-inch max undercut for non-combustible floors.

Measure twice, then once more before ordering. It's a small step that saves time, money, and frustration.

If you're handling interior upgrades, commercial wood doors are designed for offices, schools, and retail spaces where measurement precision directly affects the final installation quality.

Correct measurements give you peace of mind. You know the door will fit, meet code, and perform as expected.

Ready to move forward? Contact CDF Distributors today, and our door specialists will help you choose the right doors for your project and ensure your measurements translate into a perfect fit.