Custom Door Measurement Checklist

Three widths and three heights

Measure width at the top, center and bottom. Measure height at the left, center and right from the correct sill or threshold point. Write every reading down to the same precision and identify the smallest usable dimension rather than averaging the set.

Use a rigid tape and keep it level. For width, identify the actual frame or trim surfaces that will receive the new assembly; do not switch measurement points between the top and bottom. For height, use the sill or threshold reference required by the proposed door and state exactly where the tape ended. Record fractions consistently and never round up to a preferred retail size. Differences between readings are useful information because they reveal taper and help determine whether the opening needs correction or a sizing allowance.

Both diagonals

Measure corner to corner in both directions. A difference shows that the opening is out of square, but diagonals do not explain where the variation occurs. Pair them with the six width and height readings and straight-on photographs.

Diagonal readings are a quick square check, not a substitute for level and plumb. If one diagonal is longer, photograph the reveals and use a level to see whether the head, sill or side is moving. A parallelogram-shaped opening can have acceptable widths and heights while still causing uneven frame gaps. Do not assume the new door should be fabricated to follow every irregularity. The installer or supplier should explain what will be corrected in the field and what allowance is built into the ordered assembly.

Mounting surface and depth

Record the flat surface available on the head and both sides, jamb or trim depth, sill projection and any slope. Photograph brick, stone, siding, metal trim and repairs because the installer may need a subframe or different anchors.

Measure the flat face on the left, right and head where the outer frame or flange would sit. Note molding profiles, masonry joints, siding steps and old fastener holes. Measure depth to the primary door and the projection of its handle, because outer-door hardware occupies that same space. At the bottom, show sill angle, overhang, drain paths and transitions to porch or flooring. If wood is soft, trim is loose or masonry is cracked, resolve who repairs it before treating the measured opening as production-ready.

Swing and hardware

State hinge side from a defined viewpoint, desired swing direction, handle side and the positions of primary-door locks and handles. Measure their projection so two sets of hardware do not collide between the doors.

Always state the viewpoint when naming hinge side—this site uses viewed from outside. Photograph the primary door open and closed, then show its handle relative to the proposed outer handle. Trace the outer leaf’s swing across the landing and check rails, light fixtures, mailboxes, wall returns and wind exposure. For pairs, identify the active leaf used daily. For a gate, also record latch access and ground slope. A correct frame size cannot compensate for a leaf that collides with the building or blocks safe passage.

Obstructions and landing

Show steps, rails, lights, mailboxes, walls, planters, mats and furniture through the full swing arc. An opening can accept a frame and still be unusable because the door cannot open safely.

Measure beyond the opening itself. A step immediately outside can affect closing position and safe footing. A thick mat can interfere with the sweep. Sloped concrete may clear at the latch and rub at the hinge. Overhead trim can limit closer placement, and shallow eaves may leave the door exposed to wind. Note electrical switches, bells and lights near likely fastener locations. These conditions belong in the installation plan, even if they do not change the door’s nominal width and height.

Photo package

Send one straight-on photo from each side, the complete entry from several feet away, close-ups of all four edges and a tape visible across key dimensions. Keep original images large enough to zoom into trim and hardware details.

Take photographs in daylight without digital zoom. Include the complete doorway from far enough back to show the landing and wall, straight-on views from both sides, all four edges, hinge and latch close-ups, sill and drainage, and each unusual condition. Place the tape in the image for scale but also type the exact value; perspective makes photographs unreliable for precise measurement. Keep original-resolution files for follow-up. Label multiple openings by room or elevation so measurements and photos cannot be assigned to the wrong door.