How to Measure for a Garden Gate

How to measure for a garden gate: start with the finished opening

Decide where the gate will sit and which way it must open before taking measurements. Clear away plants, loose fittings and other obstructions so you can see both sides of the opening. Measure in millimetres with a rigid tape measure, and record each reading as you take it. A quick sketch showing the house side, garden side and intended swing will help keep the figures clear.

Identify whether you are measuring between existing posts, between a post and a wall, or across a gap that still needs posts. If new posts or cladding will reduce the opening, measure again after they are installed or obtain their finished positions from the installer. Do not treat the distance between the outer faces of posts as the gate opening. The useful width is the clear space between the surfaces that will face the gate.

• Record all dimensions in mm.
• Mark the intended hinge side and opening direction on your sketch.
• Photograph the opening with the tape visible for later reference.

Check the posts before trusting a single width

Measure between the finished inner faces near the top, around the middle and close to the bottom of the proposed gate. Write down all three readings, including the height at which each was taken. If the posts lean or the surfaces are uneven, the opening may be narrower in one place. Use the narrowest relevant reading when assessing whether a rectangular gate can fit.

Check each post with a spirit level and look for movement, rot, loose fixings or damaged masonry. A gate that fits a static measurement can still catch if its hinge post moves under load. If an existing post is unsuitable for the planned gate, arrange to repair or replace it before confirming an order size. Measure again after that work, because even a small change in post position alters the available width.

Measure height and the gate's swing

Choose the intended top line of the gate and mark it on the hinge side and latch side. Measure vertically from that line to the finished ground at both ends of the opening. Check the ground along the full path the gate will sweep, particularly where paving rises or the path slopes. The highest point beneath the swing usually sets the minimum ground clearance you need.

Think about what must pass under the gate during normal use, such as a threshold or uneven paving. Check that the chosen clearance also suits the particular gate, hinges and latch rather than relying on a universal gap. If the surface has not been laid, use its planned finished level and allow for uncertainty until it is complete. A gate measured against bare soil may sit too low once paving is added.

• Measure from the proposed top line to finished ground on both sides.
• Check the highest point across the full opening arc.
• Record any threshold, drain cover or paving edge in the swing path.

Confirm hinges, latch and fixing space

Choose the gate and hardware before converting opening width into a leaf width. Common UK garden gate fittings include tee hinges, hook-and-band hinges, ring latches and Suffolk latches, but their fitting requirements differ. Read the maker's instructions for the hinge-side and latch-side clearances required by your exact combination. Also confirm whether the product's advertised width describes the gate leaf or the opening it is designed to fill.

Check that the hinge post has enough sound material for the specified screws, bolts or other fixings. On a wall, confirm the intended fixing method is suitable for that wall before ordering hardware. Mark where the hinges, latch and any gate stop would sit, then check for clashes with post caps, brickwork or adjacent fencing. Allow room for the latch to engage when the gate is closed.

Calculate the gate leaf size

For a gate fitted between two fixed faces, start with the narrowest usable opening width. Subtract the hinge-side clearance and latch-side clearance specified for your chosen fittings. The remainder is the target leaf width, provided the maker confirms that this is how its gate should be sized. If the gate uses an overlapping frame or a different mounting arrangement, follow that product's dimension diagram instead.

For height, start with the distance from your chosen top line to the highest finished ground level in the swing. Subtract the ground clearance required for that installation to find the maximum leaf height at that top line. Check whether the gate has a frame, finials or other parts extending beyond its stated leaf dimensions. Record the opening, allowances and resulting order size separately so they cannot be confused.

• Leaf width = narrowest usable opening minus the specified side clearances.
• Maximum leaf height = top-line-to-highest-ground distance minus required ground clearance.
• Compare both results with the maker's dimension diagram and available sizes.

Resolve boundary and access questions before ordering

Check whether the gate will affect a shared boundary, a public-facing entrance or access used by someone else. GOV.UK explains that boundary records may not show the exact boundary line, so do not assume a gatepost position settles an ownership question. Discuss uncertain positions with the relevant neighbour or seek appropriate advice before moving posts. Keep the agreed position on your sketch and measure from that position.

Planning permission can depend on the location and circumstances of a gate or boundary change. GOV.UK advises checking whether permission is needed before carrying out work, and your local planning authority can advise on a particular site. This is especially worth doing if you are changing the height or position of an existing boundary feature. A correct gate measurement does not, by itself, confirm that a proposed installation is permitted.

Final verification checklist

Repeat the three width measurements with a second person holding the tape straight if the opening is awkward. Recheck the top line, the highest ground point and the complete swing with the proposed opening direction marked. Compare your written dimensions against the manufacturer's ordering instructions one last time. If posts or paving will change, wait for their finished positions before treating the figures as final.

Put the opening widths, height checks, hardware model and allowance figures together on one dated record. Label each value as an opening dimension, a required clearance or a gate leaf dimension. Give the supplier the measurements and ask them to confirm which dimension their quoted size represents. Keep the sketch and photos with the order confirmation for fitting day.

• Top, middle and bottom opening widths rechecked.
• Posts, fixing surfaces and full swing path checked.
• Maker's clearances and stated product dimensions confirmed.
• Final figures labelled and dated before ordering.

Scope and limitations

This note helps householders organise measurements and understand the calculation. It does not replace an on-site decision by a designer, installer, contractor, or manufacturer. Fabrication, structure, electrical work, gas, waterproofing, and personal safety require suitably qualified verification.