Ordering post caps that don't fit is the most common mistake people make when finishing a fence. The good news is that getting it right takes one tape measure and about a minute per post. This guide gives you the quick answer, a table of common Australian post sizes, and the few things that catch people out.
The short version: measure straight across one face of your post, then order the Ledro House post top that matches that measurement. We size every cap to the post, so a 100mm post takes a 100mm post top. If your post is an unusual size, we can make one to suit.
Step 1: Measure your post
- Measure straight across one face of the post, edge to edge. Not corner to corner.
- Measure the other face too. Many posts are square, but some are rectangular.
- Measure to the nearest millimetre, on bare timber or metal rather than over thick old paint where you can.
- If the two faces differ slightly on a square post, use the larger measurement.
Measure a few posts along the fence, not just one. Gate and corner posts are often larger than the line posts.
Step 2: Match it to the right size
Ledro House post tops are sized to match your post, so you order the size you measured. Here are the post sizes we see most often on Australian fences:
| Your post | Where you'll usually find it | Order this post top |
|---|---|---|
| 50mm or 65mm square | Steel posts on Colorbond and other steel fences | The matching size. If it isn't listed for your style, ask us |
| 75mm square | Smaller timber picket and garden fences | The matching size. If it isn't listed for your style, ask us |
| 90mm square | The most common timber fence post | 90mm |
| 100mm square | Timber fences, gate posts | 100mm |
| 115–150mm square | Gate posts, feature posts, verandah posts | The matching size |
| 160–200mm square | Large entrance and pier-style posts | The matching size |
| Rectangular, e.g. 75 x 150mm | Some gate and feature posts | A rectangular size such as the Paris 75 x 150mm, or ask us |
Each product page has a size table showing exactly which sizes that style comes in. If your measurement falls between two listed sizes, choose the next size up, or email us and we'll make it to your exact size.
Step 3: Check how the cap fits
There are two ways a Ledro House post top fits, and the Post fixing row on each product page tells you which:
- Fits over the post. The cap slides down over the top of the post. We make the internal opening 2mm larger than the listed size, so a 90mm cap has a 92mm opening and slides neatly over a 90mm post. Order the size of your post, not the opening.
- Sits on top of the post. The cap's outer size matches the listed size and sits on the flat top of the post, held by an included lag bolt fixed into the post.
What catches people out
- Nominal sizes. Timber is sold by a nominal size, and the real post can be a few millimetres different. A "90mm" post might measure 88mm or 92mm. Always order from your measurement, not the label.
- Measuring corner to corner. The diagonal of a square post is much larger than its face. Measure across a flat face.
- Thick paint. Several coats of old paint add up. Measure bare timber where you can.
- Mixed sizes on one fence. Gate and corner posts are often bigger than line posts. Measure each type.
Quick answers
What size post cap do I need for a 100mm post?
A 100mm Ledro House post top. We size every cap to match the post.
What if my post is an odd size?
Every Ledro House post top is made to order and made to suit any post size. Email us your measurement and we'll make it to fit.
Do the caps suit steel posts?
Yes. Caps that fit over the post suit square steel posts as well as timber.
Should I paint them before fitting?
Yes. Paint them with a good quality exterior paint such as Dulux Weathershield before you install them. No sanding or primer needed. See our painting and installation guide.
Find your post top
With one of Australia's widest ranges of sizes, and made-to-order sizing for anything in between, there's a Ledro House post top for almost any post. Every one is made in Australia and designed to be painted to match your fence.
Browse our traditional post tops and contemporary post tops, or email [email protected] with your post size and we'll confirm the right fit.