The short answer: a post advertised as 6x6 measures about 5.5" across, so you want a post cap light with a base plate of roughly 5.5" square. Anything much larger will overhang the edges; anything much smaller will look lost on top of the post.
That difference between the name and the measurement is the single most common reason a post cap light arrives and doesn't look right. Here's how to get it correct the first time.
A "6x6" post isn't 6 inches wide
Dimensional lumber in the US is sold by its nominal size — the rough size before it's dried and planed smooth. The actual finished size is smaller. This catches almost everyone out:
| Post is sold as | It actually measures |
|---|---|
| 4x4 | 3.5" × 3.5" |
| 6x6 | 5.5" × 5.5" |
| 8x8 | 7.25" × 7.25" |
So a 6x6 gate post is half an inch narrower than its name suggests. A light with a 6" base would overhang it by a quarter inch on every side.
Measure your post before you buy
Take a tape measure across the flat top of the post, edge to edge. Measure both directions — older posts and masonry pillars are not always square. Write down the smaller of the two numbers, because that's the one that limits you.
If you're mounting on a metal or wooden pole rather than a flat post top, you need the pole's outside diameter instead: measure straight across the widest point of the pole.
Which AmberDusk light fits which post
Every one of our lights has a removable base plate, so each can either sit flat on a post (pier mount) or slide over a pole (pole mount).
| Light | Base plate | Pole fitter | Height | Best on |
|---|---|---|---|---|
| Craftsman | 5.5" square | 3" pole | 15" | A flush fit on 6x6 posts |
| Antique Gold | 5.7" square | 3.2" pole | 20.1" | 6x6 posts, flat caps 5.7" or wider |
| Victorian (set of 2) | 7.7" square | 3" pole | 20.1" | Brick columns and masonry pillars |
On a standard 6x6 post (5.5"): the Craftsman is an exact flush fit. The Antique Gold overhangs by about a tenth of an inch per side — not something you'd notice from the driveway. The Victorian is too wide for a 6x6 and belongs on something larger.
On a brick or masonry pillar: these are usually 8" or more across, so all three will sit comfortably. The Victorian is designed for exactly this, and its larger base looks properly proportioned on a wide column where a smaller light can look undersized.
If you have 4x4 posts
We'll be straight with you: a 4x4 post measures only 3.5" across, and every light we sell has a base wider than that. The light would overhang the post on all four sides.
That overhang is cosmetic rather than a mounting problem — the base still screws down into the post top — but it does look top-heavy, and we'd rather tell you now than have you send it back. If you're set on the look, a hardwood spacer block or a post cap adapter plate sized to your fixture will square things up. Otherwise, a light designed specifically for 4x4 posts is the better buy.
Pier mount or pole mount?
Pier mount means the base plate is fitted and the light sits flat on top of a post, fence cap, or pillar. This is how most gate posts and driveway columns are done.
Pole mount means you take the base plate off, and the fitter underneath slides down over the top of a pole. Check the pole's outside diameter against the fitter size in the table above — 3" for the Craftsman and Victorian, 3.2" for the Antique Gold.
Quick answers
Do I need two lights? Most driveways and gateways have a post on each side, so a matched pair is the usual purchase. The Victorian is sold as a set of two for that reason.
Does the light need wiring? No. All of our post lights are fully solar — they charge through the day and switch on at dusk. There's no cable to run and no electrician to book.
What if my post top isn't flat? A pier mount needs a flat surface to sit on. Angled or pyramid-shaped post caps will need to be replaced with a flat cap first.
Still not sure? Measure the top of your post and send us the number — we'll tell you honestly which of our lights suits it, or whether none of them do.