How many board feet are in a 4×4×8?
A 4×4×8 is 10.67 board feet on nominal size (4 × 4 × 8 ÷ 12). The actual 3½ × 3½ in post holds about 8.17 board feet.
How to work it out
- 4 in × 4 in × 8 ft ÷ 12 = 10.67 bd ft per board
- 10.67 × 1 board = 10.67 board feet
Fence and deck posts are almost always sold by the piece, but the board-foot figure is handy for comparing a pressure-treated post with a cedar one priced per board foot, or for pricing a bundle of posts from a yard that quotes per MBF.
Adjust for your project
More options: Waste allowance · The yard quotes a price… · Price (optional) …
- Board feet per board
- 10.67 board feet
- Volume (at the size entered)
- 0.889 cu ft (0.025 m³)
- Total length of boards (before waste)
- 8 ft
- Softwood construction lumber is tallied on nominal size (2×4 = 2 × 4 in), even though it measures 1½ × 3½ in. Hardwood is tallied on rough thickness (4/4 = 1 in) even after surfacing.
Board feet in an 8 ft post by width
| Nominal size | Board feet per board | Volume (at the size entered) |
|---|---|---|
| 4×4 | 10.67 board feet | 0.889 cu ft |
| 4×6 | 16 board feet | 1.333 cu ft |
| 4×8 | 21.33 board feet | 1.778 cu ft |
What to know about a 4×4×8
- Wet posts measure fat. Pressure-treated 4×4s often leave the yard still wet from treatment and can measure a little over 3½ in until they dry — the billed 10.67 board feet does not change either way. What is the actual size of a 4x4 covers the dry and green sizes.
- Eight feet is a fence-post length. Set a couple of feet in the ground and an 8 ft post leaves roughly 6 ft above grade for a standard privacy fence — the post is the same 10.67 board feet however deep you bury it.
- Stepping up to 4×6 or 6×6. A 4×6×8 is 16 board feet and a 6×6×8 is 24, so moving from a 4×4 to a 6×6 more than doubles the wood you pay for.
If you price posts per board foot, the table below shows how fast wider posts add up at the same 8 ft length. For boards rather than posts, start with how many board feet in a 2x4x8.
Different size? Use the full Board Foot Calculator.
What you’ll need
- Post hole diggerMid-range price
The clamshell digger digs and cleans out post holes with straight sides. For many holes, rent a power auger and use this to finish.
See options on Amazon (opens in a new tab) - Speed square (7 in)Budget price
Marks square and angled crosscuts and doubles as a saw guide for a circular saw. The degree scale is handy for rafters and stair angles.
See options on Amazon (opens in a new tab) - 25 ft tape measureBudget price
A 25 ft tape with a stiff blade and a readable 1/16 in scale covers everything from cut lists to deck layout.
See options on Amazon (opens in a new tab)
As an Amazon Associate we earn from qualifying purchases. Links to products are affiliate links — they cost you nothing extra and help keep these calculators free.
Frequently asked questions
How many board feet are in a 4×4×10 post?
A 4×4×10 is 13.33 board feet (4 × 4 × 10 ÷ 12).
How many board feet are in a 4×4×12 post?
A 4×4×12 is 16 board feet — one and a third board feet per foot.
How many board feet are in a 6×6×8 post?
A 6×6×8 is 24 board feet on nominal size, well over twice a 4×4×8.
Other common sizes
- How many board feet in a 2x4x8 — 5.33 board feet
- How many board feet in a 2x6x8 — 8 board feet
- Board feet in a 4/4 hardwood board, 8 in × 8 ft — 5.33 bd ft (yard tally: 5)
- Board feet in an 8/4 slab, 24 in × 8 ft — 32 board feet
Sources
- NIST, Voluntary Product Standard PS 20-20, American Softwood Lumber Standard (Rev. 1, 2021) (opens in a new tab) — Nominal and dressed sizes of softwood lumber; board measure on nominal size.
- American Hardwood Export Council, The Illustrated Guide to American Hardwood Lumber Grades (opens in a new tab) — Board foot, surface measure and quarter (4/4, 8/4) thicknesses under the NHLA rules.
- National Hardwood Lumber Association, Rules for the Measurement & Inspection of Hardwood & Cypress (2019) (opens in a new tab) — Paragraphs 16 and 18: board feet = surface measure × standard thickness, with standard thicknesses under 1 in measured as 1 in.