How to measure for a new garage door

Use these measurements to prepare for a survey, not to place an order. Manufacturers distinguish the structural opening from the door, its frame, the ordering size and the clear passage. The installer must confirm which dimensions apply to the product and fitting method you choose.

1. Measure the opening

Measure clear width between the reveals near the top, middle and bottom. Measure height from the finished floor to the underside of the lintel on the left, centre and right. Record each reading and use the smallest as a conservative survey note. Check whether the floor is level; do not change the measurement to compensate for a slope.

2. Record headroom and side room

Headroom is the space above the opening to the ceiling or lowest obstruction. Measure on both sides and near the centre if beams or services vary. Side room is the clear space from each reveal to a wall or obstruction. Keep left and right values separate. Note brackets, pipes, storage, lights and anything fixed to the ceiling or walls.

3. Measure depth and outside clearance

Measure from the opening into the garage to the back wall or nearest obstruction. Note ceiling height, a car parked inside and how close it sits to the opening. Outside, check whether a door panel or swing would meet a vehicle, wall, path or public route. Different mechanisms move through different spaces.

4. Make a record for the survey

Write dimensions in millimetres, label each point, and take clear photos with obstructions visible. Note the door type you have now and whether you want automation. Garador’s sizing guidance illustrates why door and frame sizes are not interchangeable; its sectional specifications show that clearance also depends on track and operator configuration.

Use the garage door size checker as a first pass. Ask the installer to confirm the structural opening, order size, frame position, clear passage and required fitting clearance in writing. See garage door sizes and headroom and side room.