What frame section should I use for a steel gate?

For pedestrian gates (up to 1m wide), 40x40x3 RHS is adequate. For single vehicle gates (up to 3m), 50x50x3 or 60x40x3 RHS is standard. For double gates (3-6m total) or tall gates (over 2m), 80x40x3 or heavier sections are needed. The frame must resist self-weight deflection (sag) and wind loading without excessive flex.

How deep should gate posts be set in the ground?

Gate posts should be embedded at least 600mm into the ground for pedestrian gates, and 900-1200mm for vehicle gates. A general rule is one-third of the total post length below ground. The post should be set in a concrete foundation (C25 minimum) at least 300mm diameter for pedestrian and 450mm for vehicle gates.

How do I size hinges for a steel gate?

Hinges are sized by the gate weight and frequency of use. For gates under 50kg: 16mm pin, 150mm strap. For 50-100kg: 20mm pin, 200mm strap. For 100-200kg: 25mm pin with ball bearing, 250mm strap. Heavy gates (over 200kg) need 30mm pin ball-bearing hinges. Use 3 hinges for gates over 100kg or over 2m tall.

What do I need for an automated gate?

Automated gates require: (1) a gate motor matched to gate weight (ram actuator for swing, rack and pinion for sliding), (2) safety features per BS EN 13241 — photocells, safety edges, warning lights, (3) adequate power supply (230V or 24V with battery backup), (4) manual release mechanism for power failure. Installation must comply with the Machinery Directive.

What finish should I use for external steel gates?

For UK external use, hot-dip galvanising (to BS EN ISO 1461) is essential for long-term durability. This can be left as-is (grey) or overcoated with powder coating for a colour finish (duplex system — 25+ year life). Alternatively, galvanise and apply two-pack polyurethane paint. Never paint raw steel without galvanising for external gates.

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Steel Gate Calculator — Frame, Hinges & Post Sizing

Calculate steel gate requirements: frame section from gate weight and wind load, hinge sizing, post embedment depth, and foundation sizing. Covers swing and sliding gates.

Gate Width

Single gate leaf width

Gate Height

Height above ground level

Gate Type

Opening mechanism

Infill Type

Affects weight and wind loading

How We Calculate This

This calculator determines the structural requirements for a fabricated steel gate, including frame section, hinge sizing, post specification, and foundation dimensions.

Design considerations

Gate weight: Frame + infill + hardware, determines hinge and motor size
Wind load: Pressure × area × solidity factor
Post embedment: Minimum 600mm, deeper for heavy or automated gates
Foundation: Concrete base to resist overturning from wind and gate weight

Frequently Asked Questions

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Last updated: March 2026

All calculations are estimates. Verify with your supplier.