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4x4 Wood Post Caps
4x4 wood post caps fit a post measuring 3 1/2 to 3 5/8 inches. Several caps also come in an oversized size for posts measuring about 3 3/4 inches, and the Pyramid Miterless Wood Post Cap™ comes in a FULL 4" size for rough-cut posts. Please measure before you order.
We have (13) 4x4 Wooden products available.
Select one below to choose the 4x4 size.
Why a 4x4 post needs a cap
The 4x4 is the post used most often on fences, decks and porch railings, and the upper end of every one of them is end grain: the cut ends of the wood fibers. End grain takes in water much faster than the sides of a post. Rain and snow that sit on a flat post end soak straight down into it, and that is where checking, splitting and rot usually start.
A wood post cap covers the end grain and sheds water off the post. It also gives every post a finished look, and because it is wood, it can be stained or painted to match the fence, the deck or white trim on the house.
How to measure a 4x4 post
"4x4" is the name of the post, not its measurement. A 4x4 sold at a lumberyard has been planed smooth on all four sides, and it measures about 3 1/2 inches across. Each standard 4x4 wood cap fits a post measuring 3 1/2 to 3 5/8 inches.
Some 4x4 posts measure a little more than that, and a rough-cut post that has not been planed measures a full 4 inches. Those posts need an oversized 4x4 cap or a FULL 4" cap. Ordering the wrong size is the most common reason post caps are returned, so measure every post before you order.
| Your 4x4 post measures | Size to choose | Available in |
|---|---|---|
| 3 1/2 to 3 5/8 in | Standard 4x4 | Every cap on this page |
| About 3 3/4 in | Oversized 4x4 | Six of the caps on this page. See the style table below. |
| Up to 4 1/8 in (rough-cut) | FULL 4" | Pyramid Miterless Wood Post Cap™ |
The ball and acorn finials screw onto the post instead of slipping over it. Each one fits a 4x4 post measuring 3 1/2 inches.
Where to measure
Measure across the flat face right at the upper end of the post, from one side to the other. Do not measure corner to corner, and do not measure partway down. Measure in both directions, because an older post is often no longer perfectly square, and use the larger figure.
Four things to check before you order
Pressure-treated lumber shrinks as it dries. A new post that is still wet can measure slightly larger than it will in a few months. If your measurement is near the high end of a range, measure again before ordering.
A wrapped post is larger than the post inside. If the post has trim boards or a sleeve around it, measure the outside of the wrap.
The post should be cut flat and square. A slip-over cap sits evenly on a level, square cut. If the post was cut at an angle, trim it square before the cap goes on.
A split or soft post end needs attention first. Cut back to sound wood before the cap goes on. A post cap protects a sound post. It will not repair one that has already started to rot.
Ordering for a whole project
Measure every post, not just one, whether the fence is new or old. Sizes on the same fence or deck can differ, especially where a post has been replaced over the years. Write down the size of each post and group them, so you order the right number of standard, oversized and FULL caps.
What Miterless means
One piece of mahogany, no corners to split
Most wood post caps are built from five pieces of wood, a top and four sides, stapled or glued together at the corners. The corners are where they fail. As the wood swells and shrinks with the weather, the joints open, and water runs into the post instead of off it.
Miterless Wood Post Caps™ are cut from a single piece of mahogany. The underside is routered out, so the cap slips over the post and covers the end and the upper part of each side, with no joints, staples or glue at the corners. Each cap is hand sanded, and the wood is kiln-dried for 30 days.
Because there are no joints, every Miterless cap is guaranteed for life never to split apart at the corners. If one does, we replace it with a product of equal value. Like all wood, a Miterless cap can still check and weather naturally over the years. The guarantee covers the corners.
Choosing a 4x4 wood post cap style
Every cap on this page fits a standard 4x4 post measuring 3 1/2 to 3 5/8 inches. The difference is the shape of the cap, how it mounts, and whether it is all wood or wood and metal. Choose Options on any product above to see its details, sizes and current price.
| 4x4 wood post cap | Shape | Mounting | Larger 4x4 sizes |
|---|---|---|---|
| Pyramid Miterless | Low, sloped wood | Construction adhesive | Oversized and FULL 4" |
| West Indies Miterless | Low, flat New England style | Construction adhesive | Standard only |
| 4x4 Traditional Pyramid Miterless | Tall, sloped wood on a stepped base | Construction adhesive | Oversized |
| 4x4 Original Miterless | Raised flat panel on a stepped base | Construction adhesive | Oversized |
| Wood ball | Round ball finial | One wood screw, included | Standard only |
| Wood Acorn | Acorn finial | One wood screw, included | Standard only |
| West Indies with metal lid | Copper, hammered copper, stainless or black stainless | Construction adhesive | Standard only |
| 4x4 Traditional with metal lid | Copper, hammered copper or stainless | Construction adhesive | Oversized |
Every Miterless cap is one piece of 100% mahogany. The metal lids are 20-gauge and go on the wood base when the cap arrives.
Pyramid
A low, sloped shape that sheds water. It is the one cap here that also comes in a FULL 4" size for a rough-cut post.
Traditional Pyramid
A taller, steeper slope on a stepped base, for a more formal look on a deck or porch railing.
Original
A raised flat panel on the same stepped base, for a white picket fence or a modern deck.
Ball top and acorn
A round ball or an acorn, made from one piece of mahogany, that screws onto the post. Often used to mark a gate or the end of a run.
Wood caps with a metal top
Seven of the caps on this page pair a one-piece mahogany base with a separate 20-gauge metal pyramid: copper, hammered copper, stainless steel or black stainless steel. The wood base can be stained or painted to match the fence, and the metal adds a finished accent to each post.
The base and the lid come as separate pieces and go together when they arrive. On the 4x4 Traditional caps, the metal lid fastens to the base with screws that are included. The finished cap then glues onto the post like any other Miterless cap.
Copper weathers from new, bright copper to bronze and then dark brown over the years. A clear protective spray made for copper, sold separately, keeps the original sheen. Stainless steel keeps its sheen without it.
Staining or painting wood post caps
Miterless caps can be stained, painted or finished with a clear wood gloss, so they can match a stained fence, a white porch railing or white trim on the house.
Stained
Caps stained with the posts on a wire-panel fence.
Painted
Caps painted white to match a white railing.
Finish new caps before they go on the posts, so you can reach every face, including the routered underside that sits against the post. Use a stain, paint or clear finish made for outdoor wood, and follow the directions on the can. If the posts and caps should match, finish them with the same product at the same time.
How 4x4 wood post caps install
The caps on this page install two different ways, depending on their shape.
Slip-over caps: construction adhesive
The Miterless caps slip over the post and glue on with construction adhesive such as Liquid Nails, which is sold separately.
1Make sure the post top is flat and dry. Adhesive does not bond well to wet wood.
2If the cap has a metal lid, put the lid and the base together first.
3Apply construction adhesive to the end of the post, following the directions on the tube.
4Set the cap on the post and check that it sits evenly on all four sides.
5Wipe away any adhesive that squeezes out before it sets.
Ball and acorn finials: one screw, included
The ball and acorn finials screw onto the post. Each one comes with a self-threading wood screw that holds it in place. Center the finial on the post before you fasten it, so it sits square to the rail.
Like the Miterless caps, both finials are made from one piece of mahogany.
Where 4x4 wood post caps are used
The 4x4 is the standard post on most residential fences and railings, so 4x4 caps cover a wide range of projects.
Fences. Line posts, gate posts and corner posts on stained or white picket fences, privacy fences and wire-panel fences.
Deck and porch railings. The posts along a stained deck rail or a white porch rail, including the posts at each end of a stair.
Garden borders. Low garden fences and the posts around planting beds and walkways.
Mailbox posts. A 4x4 mailbox post takes the same cap as a fence post.
4x4 post caps in other materials
Wood is one of four materials we make 4x4 post caps in. Each one fits the same post and gives it a different look.
4x4 Wood Post Caps
This page. One-piece mahogany caps that can be stained or painted to match.
Shop 4x4 Copper Post Caps
All-copper caps stamped from one piece of 20-gauge copper and left to patina naturally.
Shop 4x4 Stainless Steel Post Caps
Stainless steel stays bright and does not develop a patina.
Shop 4x4 Black Post Caps
Black stainless steel tops, for black railing and dark-stained wood.
For round posts and pilings, see our round piling caps.
Questions about 4x4 wood post caps
My 4x4 post measures 3 1/2 inches. Which size do I need?
A standard 4x4 cap. A planed 4x4 post measures about 3 1/2 inches, and each standard 4x4 cap fits a post from 3 1/2 to 3 5/8 inches.
What is the difference between an oversized 4x4 cap and a FULL 4" cap?
An oversized 4x4 cap fits a post measuring about 3 3/4 inches. A FULL 4" cap fits a rough-cut post measuring up to 4 1/8 inches, and it is available in the Pyramid Miterless Wood Post Cap™.
Will a 4x4 cap fit a 4x6 post?
No. A 4x6 post measures about 3 1/2 by 5 1/2 inches and needs a 4x6 cap. See our 4x6 wood post caps.
Is adhesive included?
No. The slip-over Miterless caps mount with construction adhesive such as Liquid Nails, which is sold separately. The ball and acorn finials come with the screw they need.
What if I order the wrong size?
Call or email us for a return authorization before sending anything back. New, unopened items can be returned within 30 days of delivery. Returns carry a 20% restocking charge unless the product is defective. We do not refund the original shipping charge, and return shipping is at the buyer's expense unless the error was ours, so please measure first. Our Shipping & Returns page has the full details.
How many post caps do I need?
One per post. Count every gate, corner and stair post as well as each line post.
Not sure which cap is right?
Call us at 678-909-2720 with your post measurements and a description of your fence or deck.
Shop wood post caps in other sizes
4x6 Wood Post Caps · 5x5 Wood Post Caps · 6x6 Wood Post Caps · All Miterless Wood Post Caps™