How to Measure for a Metal Gate: A Practical Guide for Perfect Gate Installation
You are planning a bespoke garden gate or a pair of double metal driveway gates, but don’t know where to start? Keep in mind that accurate measurements are the foundation of a good fit. At our workshop we design every gate to suit its setting. That starts with understanding the clear opening measurement.
Continue reading if you want to know how to measure for a metal gate, what to consider, and why a little breathing room matters for a smooth gate installation.
How to Measure for a Metal Gate and Determine Dimensions
To accurately measure a metal gate, you'll need:
a tape measure;
a level;
and ideally, a helping hand.
The most important thing is to measure the clear opening, not the gate itself (if you already have one). You need to measure the distance between two fixed points (posts or a wall) where the gate will be installed.
For single gates: Measure the width between the two walls, posts, or piers where the gate will hang.
For double gates: Measure the full span between the two sides. This is your total driveway gate size. Divide by two to determine each leaf’s width, allowing for gaps, you will read more on that below.
Measure at three heights: Top, middle, and bottom. Use the smallest size to prevent the gate from getting stuck on uneven surfaces.
Check the height: Measure from the ground up to your desired gate height, factoring in any slope or step.
If you're replacing an old gate, don’t assume the existing one was sized correctly. You always have to measure the opening itself to determine the correct garden gate dimensions.
How to Measure the Opening for a Gate
The “opening” refers to the gap between the two fixed structures, for example, brick piers, timber posts, or steel uprights. This is the dimension we use to size your gate.
Measure from face to face of the posts or walls, not from the centres or edges.
If you plan to install new posts, measure the gap where they will be installed, not the overall width of the opening.
For sloped ground, note the gradient. We may recommend a raked bottom edge or stepped design.
Tip: Take a photo of the opening and note any obstructions, like pipes, hinges, uneven ground. This helps us design a bespoke metal gate that will fit beautifully and function smoothly.
How Much Smaller Should a Gate Be Than the Opening?
Remember that the gate width should always be slightly smaller than the opening width. This is necessary to ensure the gate moves freely and doesn't rub against the hinges and latches. The exact width of single metal gates depends on the type of gate and hardware, but here's a general guideline for answering the question: how much smaller should the gate width be than the opening width?
Single gates: subtract approximately 20-30 mm from the opening width.
Double gates: subtract 30-40 mm, dividing this between the center gap and the side gaps.
If you allow for these gaps, the gate will move freely and won't bind, even if the posts shift slightly over time.
What is the Size Gap for Metal Gate Hinges?
To correctly calculate side clearances, you need to take into account the gap between the hinges and thermal expansion. This will determine the required clearance size for metal gate hinges. Typical allowances are:
| Gate Type | Side Gap (Each Side) | Centre Gap (Double Gates) |
|---|---|---|
| Single Gate | 10–15mm | Cell |
| Double Gates | 10–15mm | 10–20mm |
Gaps can vary in size depending on the hinge type (such as butt hinges or adjustable hinges), latch style, and whether the gate is framed or frameless.
Final Thoughts
Measuring metal gate openings isn't difficult, but it does require careful attention. If you're unsure, we're happy to help. Oakhanger Metalworks offers on-site inspections in Hampshire, Surrey, and the surrounding areas. You'll be confident your finished gate will fit perfectly, down to the millimeter.
Need help planning your metal gate installation? Get in touch for a friendly chat or a no-obligation quote.