African Mahogany wood movement, board-foot & weight calculator
- Janka
- 830lbf
- Density
- 29.4lb/ft³
- T/R ratio
- 1.8
- Spec. gravity
- 0.42
African Mahogany (Khaya spp.) is an imported species. It has a Janka side hardness of 830 lbf, a specific gravity of 0.42, and an air-dry density near 29 lb/ft³ (471 kg/m³) (mechanical values at 12% moisture content). It shrinks 4.5% tangentially and 2.5% radially from green to oven-dry (T/R ratio 1.8), so a 12-inch flatsawn board moves about 0.11 in (≈ 3/32 in) across a 6-point moisture swing (about 6%→12% MC).
Compute African Mahogany: movement, weight & board footage
Every number below is worked from African Mahogany'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″ | 0.018″ (≈ 1/32 in) | 0.01″ (≈ 0 in) |
| 3″ | 0.027″ (≈ 1/32 in) | 0.015″ (≈ 0 in) |
| 4″ | 0.036″ (≈ 1/32 in) | 0.02″ (≈ 1/32 in) |
| 6″ | 0.054″ (≈ 1/16 in) | 0.03″ (≈ 1/32 in) |
| 8″ | 0.072″ (≈ 1/16 in) | 0.04″ (≈ 1/32 in) |
| 10″ | 0.09″ (≈ 3/32 in) | 0.05″ (≈ 1/16 in) |
| 12″ | 0.108″ (≈ 3/32 in) | 0.06″ (≈ 1/16 in) |
| 16″ | 0.144″ (≈ 5/32 in) | 0.08″ (≈ 3/32 in) |
Need a different width or moisture swing? Run the movement calculator preloaded with African Mahogany. At a T/R ratio of 1.8, African Mahogany is stable — it moves moderately more across the face than through the thickness — normal behaviour for a furniture hardwood, and predictable if boards are acclimatised before milling.
Board footage & weight, standard sizes
| Nominal size × length | Board feet | Weight |
|---|---|---|
| 1×4 × 8′ | 2.67 bd ft | 6.5 lb |
| 1×6 × 8′ | 4 bd ft | 9.8 lb |
| 1×8 × 8′ | 5.33 bd ft | 13.1 lb |
| 1×10 × 8′ | 6.67 bd ft | 16.3 lb |
| 1×12 × 8′ | 8 bd ft | 19.6 lb |
| 2×4 × 8′ | 5.33 bd ft | 13.1 lb |
| 2×6 × 8′ | 8 bd ft | 19.6 lb |
| 2×8 × 8′ | 10.67 bd ft | 26.1 lb |
Different length or size? Run the board foot calculator or the weight calculator, both preloaded with African Mahogany.
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 | 0.083″ (≈ 3/32 in) |
| Chicago, IL | May · 12.3% | Dec · 15.1% | 2.8 pts | 0.05″ (≈ 1/16 in) |
| Miami, FL | Apr · 12.2% | Sep · 14.4% | 2.2 pts | 0.04″ (≈ 1/32 in) |
| Boston, MA | Apr · 11.5% | Sep · 12.8% | 1.3 pts | 0.023″ (≈ 1/32 in) |
| Denver, CO | Jul · 8% | Dec · 10.5% | 2.5 pts | 0.045″ (≈ 1/32 in) |
| Seattle, WA | Jul · 12% | Dec · 16.9% | 4.9 pts | 0.088″ (≈ 3/32 in) |
Driven by African Mahogany's tangential shrinkage of 4.5%. These are outdoor equilibrium-moisture figures, so they are an upper bound — a climate-controlled interior swings less. How this is calculated.
How African Mahogany compares
Ranked against the 196 species in the Wood Handbook tables this site carries.
- Hardness: at 830 lbf, African Mahogany is harder than 42% of the 157 species with a Janka figure.
- Weight: at 29.4 lb/ft³ it is heavier than 25% of the 170 species measured — an 8-foot 1×6 board weighs about 9.8 lb.
- Stability: its T/R ratio of 1.8 is more even than 54% of the 196 species here — as humidity changes, 46% of them hold their shape more evenly.
See African Mahogany 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 African Mahogany is unavailable or priced out.
- Yellow-poplar is a common substitute for African Mahogany : 35% softer, about the same weight, and similarly stable in service.
- Sitka Spruce is a common substitute for African Mahogany : 39% softer, about the same weight, and similarly stable in service.
- Red Alder is a common substitute for African Mahogany : 29% softer, about the same weight, and similarly stable in service.
- Red Pine is a common substitute for African Mahogany : 33% softer, 9% heavier, and similarly stable in service.
| Species | Janka | Density | T/R |
|---|---|---|---|
| Yellow-poplar | 540 lbf | 29.4 | 1.78 |
| Sitka Spruce | 510 lbf | 28 | 1.74 |
| Red Alder | 590 lbf | 28.7 | 1.66 |
| Red Pine | 560 lbf | 32.1 | 1.89 |
About African Mahogany
The bulk of “African mahogany” shipped from west-central Africa is Khaya ivorensis, the most widely distributed and plentiful species of the genus found in the coastal belt of the so-called high forest. The closely allied species K. anthotheca has a more restricted range and is found farther inland in regions of lower rainfall but well within the area now being used for the export trade. The heartwood varies from pale pink to dark reddish brown. The grain is frequently interlocked, and the texture is medium to coarse, comparable with that of American mahogany (Swietenia macrophylla). The wood is easy to dry, but machining properties are rather variable. Nailing and gluing properties are good, and an excellent finish is readily obtained. The wood is easy to slice and peel. In decay resistance, African mahogany is generally rated as moderately durable, which is below the durability rating for American mahogany. Principal uses for African mahogany include furniture and cabinetwork, interior woodwork, boat construction, and veneer.
Durability & sustainability
Decay resistance: the Wood Handbook rates African Mahogany heartwood moderately resistant 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 | 0.42 |
|---|---|
| Janka hardness (side) | 830 lbf |
| Density (air-dry, 12% MC) | 29.4 lb/ft³ (471 kg/m³) ovendry-weight basis: 26.2 lb/ft³ |
| Weight per board foot (air-dry) | 2.45 lb |
| Radial shrinkage (green→oven-dry) | 2.5% |
| Tangential shrinkage (green→oven-dry) | 4.5% |
| Volumetric shrinkage (green→oven-dry) | 8.8% |
| T/R ratio (stability indicator) | 1.8 |
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.