A post cap fits the actual outside width and depth of your post. The size on a lumber label or sleeve package is not enough to choose the right cap. Use this guide to compare nominal 4×4 and 6×6 posts with the five actual sizes offered by Newman Outdoor Works.
Measure before choosing a cap
- Measure the outside width and depth at the top of the post. Record both measurements in inches.
- If the post has a sleeve, measure the outside of the sleeve. The cap sits over that surface, not the wood inside it.
- Match the measurements to the product's stated fit. Compare the post size, not the cap's decorative roof width.
- Check each post if sizes vary. If your measurements fall between sizes, contact us with the width and depth before ordering.
4×4 and 6×6 post-cap size chart
| Your measured post | How this size is often described | Matching caps |
|---|---|---|
| 3.5″ × 3.5″ | Nominal 4×4 wood post | Caps for 3.5-inch posts |
| 4″ × 4″ | Actual 4-inch post or sleeve | Caps for 4-inch posts |
| 4.5″ × 4.5″ | Actual 4.5-inch post or sleeve | Caps for 4.5-inch posts |
| 5.5″ × 5.5″ | Nominal 6×6 wood post | Caps for 5.5-inch posts |
| 6″ × 6″ | Actual 6-inch post or sleeve | Caps for 6-inch posts |
Wood and sleeve dimensions can vary. Your own measurements take priority over the nominal size.
Choose plain, decorative, solar, or planter styles
Plain and decorative non-solar caps: Choose a direct-fit size from the chart. Plain, low-roof brick-base, and high-roof brick-base designs are available in black, white, marble, natural green, and olive brown. Shop all fence and deck post caps.
Solar post caps and lanterns: Read the individual listing for the post size and any included adapter. Adapter information applies to the specified solar model; it does not change the direct-fit sizing of non-solar caps. Shop solar post cap lights or solar post lanterns.
Post cap planters: Our planter sizes fit actual 4″, 4.5″, 5.5″, or 6″ square posts. The 4-inch planter does not fit a 3.5″ × 3.5″ wood post directly. Each planter has a rear drainage hole for flowers planted in soil. Plants, soil, and posts are not included. Shop post cap planters.
Check the fit before installation
Compare the delivered cap with your measurements and check its fit before fastening it. Do not force a cap onto a post that is too large. Use the mounting guidance supplied for your particular product; contact us if you need help with a sleeve or an unusual measurement.
Why we use ASA outdoors
We manufacture our caps and planter bodies in Ohio from UV-resistant ASA, an engineering plastic chosen for sunlight, moisture, and changing weather. Learn more about our material and Ohio workshop.