Skip to content
ENExplore Calculators

Gate Size Calculator

Work out gate size instantly with clear inputs, formula shown and shareable results.

About Gate Size Calculator

Leaf width is the opening less the clearances at each joint, divided by the number of leaves. A single leaf has two clearances, hinge and latch side; a double leaf has three because of the meeting stile. The diagonal brace length is the hypotenuse of the leaf, and it must run from the bottom hinge upward to work in compression.

Formulas

Leaf width

Leaf = (opening - clearance x (leaves + 1)) / leaves

Brace

Brace length = sqrt(leaf width² + height²)

Worked example

With the default values below, Gate Size Calculator returns Leaf width of 1,470. Change any input above and every figure here is recalculated in your browser.

Inputs used

Structural opening widthminimum 100 mm
3,000 mm
Number of leavesone of Single leaf, Double leaf
Double leaf
Gate heightminimum 100 mm
1,800 mm
Clearance per jointminimum 0 mm
20 mm

Results

Leaf width
1,470 mm
Diagonal brace length
2,324 mm
Total clearance allowed
60 mm
Area per leaf
2.646 m²

Step by step

  1. 1Values used
  2. 2Leaf width
  3. 3Brace
  4. 4Leaf width= 1,470 mm
  5. 5Diagonal brace length= 2,324 mm
  6. 6Total clearance allowed= 60 mm
  7. 7Area per leaf= 2.646 m²

Assumptions and limits

  • The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is the Gate Size figure worked out?

Leaf = (opening - clearance x (leaves + 1)) / leaves. Leaf width is the opening less the clearances at each joint, divided by the number of leaves.

Which way should the brace run?

From the bottom hinge corner up to the top latch corner, so it carries the sagging load in compression. Fitted the other way it works in tension and will stretch or pull its fixings.

What values do I need to enter?

This calculator takes 4 inputs: Structural opening width, Number of leaves, Gate height, Clearance per joint. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.

Related Calculators

Gate Size Calculator | Calcrivo