Gate Sizing Calculator

Standard pedestrian gates are 900mm to 1000mm wide. On accessible/adaptable (M4(2)) or wheelchair-user (M4(3)) dwellings, Approved Document M requires a minimum 850mm CLEAR opening width — measured between the leaf face and the opposite stop with the gate open — so the leaf itself needs to be a little wider (around 900mm+) once the hinge offset and clearances are accounted for. Side access gates are typically 900mm-1200mm wide, while single driveway gates are 2.4m-3.6m.

Hinge selection depends on gate weight: Tee hinges suit light gates up to 20kg; Hook & Band hinges handle 20-50kg; Heavy-duty cranked hinges suit 50-100kg; Ball bearing hinges are needed for gates over 100kg. Use 3 hinges instead of 2 for gates over 1.5m tall or over 30kg to prevent sagging.

A typical gate latch sits 900-1050mm from ground level. On Part M accessible (M4(2)) and wheelchair-user (M4(3)) dwellings, Approved Document M Volume 1 requires door entry controls to be mounted 900-1000mm above finished ground level and at least 300mm clear of any projecting corner, operable with one hand without tight grasping. A lever-action thumb latch or ring latch at around 1000mm suits this.

For accessible/adaptable (M4(2)) and wheelchair-user (M4(3)) dwellings, Approved Document M Volume 1 sets out: a minimum 850mm clear opening width to the gate; a minimum 300mm nib to the leading edge of the door/gate (so a wheelchair user can reach the handle), with that extra width maintained for at least 1200mm beyond; a maximum 200mm reveal depth on the leading side; door entry controls 900-1000mm above ground level; and an accessible threshold with any upstand no more than 15mm. Note there is no Part M self-closer/auto-closer requirement for dwelling gates — self-closers are a fire-door (Approved Document B) matter, not Part M. Standard M4(1) visitable dwellings only require a 775mm clear opening to the entrance door, not 850mm.

Allow 3-6mm clearance on the hinge side (depending on hinge type) and 2-3mm on the latch side. Leave at least 50mm ground clearance to allow for ground movement and prevent the gate dragging. For double gates, allow 6-10mm gap between the two leaves. These clearances accommodate swelling in timber gates.