Okoume wood movement, board-foot & weight calculator
- Janka
- 380lbf
- Density
- 23.1lb/ft³
- T/R ratio
- 1.5
- Spec. gravity
- 0.33
Okoume (Aucoumea klaineana) is an imported species. It has a Janka side hardness of 380 lbf, a specific gravity of 0.33, and an air-dry density near 23 lb/ft³ (370 kg/m³) (mechanical values at 12% moisture content). It shrinks 6.1% tangentially and 4.1% radially from green to oven-dry (T/R ratio 1.5), so a 12-inch flatsawn board moves about 0.15 in (≈ 5/32 in) across a 6-point moisture swing (about 6%→12% MC).
Compute Okoume: movement, weight & board footage
Every number below is worked from Okoume's own shrinkage and density figures, not looked up from a table — change the width, moisture swing, or board size in the calculators linked alongside.
Cross-grain movement by board width
| Board width | Flatsawn (tangential) | Quartersawn (radial) |
|---|---|---|
| 2″ | 0.024″ (≈ 1/32 in) | 0.016″ (≈ 1/32 in) |
| 3″ | 0.037″ (≈ 1/32 in) | 0.025″ (≈ 1/32 in) |
| 4″ | 0.049″ (≈ 1/16 in) | 0.033″ (≈ 1/32 in) |
| 6″ | 0.073″ (≈ 1/16 in) | 0.049″ (≈ 1/16 in) |
| 8″ | 0.098″ (≈ 3/32 in) | 0.066″ (≈ 1/16 in) |
| 10″ | 0.122″ (≈ 1/8 in) | 0.082″ (≈ 3/32 in) |
| 12″ | 0.146″ (≈ 5/32 in) | 0.098″ (≈ 3/32 in) |
| 16″ | 0.195″ (≈ 3/16 in) | 0.131″ (≈ 1/8 in) |
Need a different width or moisture swing? Run the movement calculator preloaded with Okoume. At a T/R ratio of 1.49, Okoume is very stable — it moves almost as much radially as tangentially, so flatsawn boards have little reason to cup and wide panels stay flat with ordinary care.
Board footage & weight, standard sizes
| Nominal size × length | Board feet | Weight |
|---|---|---|
| 1×4 × 8′ | 2.67 bd ft | 5.1 lb |
| 1×6 × 8′ | 4 bd ft | 7.7 lb |
| 1×8 × 8′ | 5.33 bd ft | 10.3 lb |
| 1×10 × 8′ | 6.67 bd ft | 12.8 lb |
| 1×12 × 8′ | 8 bd ft | 15.4 lb |
| 2×4 × 8′ | 5.33 bd ft | 10.3 lb |
| 2×6 × 8′ | 8 bd ft | 15.4 lb |
| 2×8 × 8′ | 10.67 bd ft | 20.5 lb |
Different length or size? Run the board foot calculator or the weight calculator, both preloaded with Okoume.
Seasonal movement by city
| City | Driest month (EMC) | Most-humid month (EMC) | EMC swing | 12″ board movement |
|---|---|---|---|---|
| Phoenix, AZ | Jun · 4.4% | Dec · 9% | 4.6 pts | 0.112″ (≈ 1/8 in) |
| Chicago, IL | May · 12.3% | Dec · 15.1% | 2.8 pts | 0.068″ (≈ 1/16 in) |
| Miami, FL | Apr · 12.2% | Sep · 14.4% | 2.2 pts | 0.054″ (≈ 1/16 in) |
| Boston, MA | Apr · 11.5% | Sep · 12.8% | 1.3 pts | 0.032″ (≈ 1/32 in) |
| Denver, CO | Jul · 8% | Dec · 10.5% | 2.5 pts | 0.061″ (≈ 1/16 in) |
| Seattle, WA | Jul · 12% | Dec · 16.9% | 4.9 pts | 0.12″ (≈ 1/8 in) |
Driven by Okoume's tangential shrinkage of 6.1%. These are outdoor equilibrium-moisture figures, so they are an upper bound — a climate-controlled interior swings less. How this is calculated.
How Okoume compares
Ranked against the 196 species in the Wood Handbook tables this site carries.
- Hardness: at 380 lbf, Okoume is harder than 4% of the 157 species with a Janka figure — one of the softer woods here, easy to work and easy to dent.
- Weight: at 23.1 lb/ft³ it is heavier than 5% of the 170 species measured — an 8-foot 1×6 board weighs about 7.7 lb.
- Stability: its T/R ratio of 1.49 is more even than 86% of the 196 species here — as humidity changes, 14% of them hold their shape more evenly.
See Okoume plotted against every species we carry: the full Janka hardness chart and the full density chart .
Species with a similar working profile
Closest matches on hardness, weight and stability together — useful when Okoume is unavailable or priced out.
- Ponderosa Pine is a common substitute for Okoume : 21% harder, 21% heavier, and similarly stable in service.
- Spanish-cedar is a common substitute for Okoume : 58% harder, 24% heavier, and similarly stable in service.
- Old Growth Redwood is a common substitute for Okoume : 26% harder, 21% heavier, and less stable in service.
- Red Alder is a common substitute for Okoume : 55% harder, 24% heavier, and less stable in service.
| Species | Janka | Density | T/R |
|---|---|---|---|
| Ponderosa Pine | 460 lbf | 28 | 1.59 |
| Spanish-cedar | 600 lbf | 28.7 | 1.5 |
| Old Growth Redwood | 480 lbf | 28 | 1.69 |
| Red Alder | 590 lbf | 28.7 | 1.66 |
About Okoume
The natural distribution of okoume (Aucoumea klaineana) is rather restricted; the species is found only in west-central Africa and Guinea. However, okoume is extensively planted throughout its natural range. The heartwood is salmon-pink in color, and the narrow sapwood is whitish or pale gray. The wood has a high luster and uniform texture. The texture is slightly coarser than that of birch (Betula). The nondurable heartwood dries readily with little degrade. Sawn lumber is somewhat difficult to machine because of the silica content, but the wood glues, nails, and peels into veneer easily. Okoume offers unusual flexibility in finishing because the color, which is of medium intensity, permits toning to either lighter or darker shades. In the United States, okoume is generally used for decorative plywood paneling, general utility plywood, and doors. Other uses include furniture components, joinery, and light construction.
Durability & sustainability
Decay resistance: the Wood Handbook rates Okoume heartwood slightly or nonresistant to fungal decay . Ratings are for heartwood only and the table's own note cautions that resistance varies substantially within a species; treat this as a general indicator, not a guarantee, especially for ground contact. Wood Handbook, Chapter 14: Biodeterioration of Wood (Arango, Lebow, Glaeser), USDA Forest Products Laboratory, FPL-GTR-282 (2021), Table 14-1. Public domain.
Properties
| Specific gravity | 0.33 |
|---|---|
| Janka hardness (side) | 380 lbf |
| Density (air-dry, 12% MC) | 23.1 lb/ft³ (370 kg/m³) ovendry-weight basis: 20.6 lb/ft³ |
| Weight per board foot (air-dry) | 1.93 lb |
| Radial shrinkage (green→oven-dry) | 4.1% |
| Tangential shrinkage (green→oven-dry) | 6.1% |
| Volumetric shrinkage (green→oven-dry) | 11.3% |
| T/R ratio (stability indicator) | 1.5 |
Shrinkage is total green-to-oven-dry (Table 4-4); strength values are at 12% MC. Full bases and the derivation formulas are on the methodology page.
Data: USDA Forest Products Laboratory, Wood Handbook FPL-GTR-282 (2021), public domain.