True Mahogany wood movement, board-foot & weight calculator
- Janka
- 800lbf
- Density
- 31.4lb/ft³
- T/R ratio
- 1.4
- Spec. gravity
- 0.45
True Mahogany (Swietenia macrophylla) is an imported species. It has a Janka side hardness of 800 lbf, a specific gravity of 0.45, and an air-dry density near 31 lb/ft³ (503 kg/m³) (mechanical values at 12% moisture content). It shrinks 4.1% tangentially and 3% radially from green to oven-dry (T/R ratio 1.4), so a 12-inch flatsawn board moves about 0.1 in (≈ 3/32 in) across a 6-point moisture swing (about 6%→12% MC).
Compute True Mahogany: movement, weight & board footage
Every number below is worked from True 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″ | 0.016″ (≈ 1/32 in) | 0.012″ (≈ 0 in) |
| 3″ | 0.025″ (≈ 1/32 in) | 0.018″ (≈ 1/32 in) |
| 4″ | 0.033″ (≈ 1/32 in) | 0.024″ (≈ 1/32 in) |
| 6″ | 0.049″ (≈ 1/16 in) | 0.036″ (≈ 1/32 in) |
| 8″ | 0.066″ (≈ 1/16 in) | 0.048″ (≈ 1/16 in) |
| 10″ | 0.082″ (≈ 3/32 in) | 0.06″ (≈ 1/16 in) |
| 12″ | 0.098″ (≈ 3/32 in) | 0.072″ (≈ 1/16 in) |
| 16″ | 0.131″ (≈ 1/8 in) | 0.096″ (≈ 3/32 in) |
Need a different width or moisture swing? Run the movement calculator preloaded with True Mahogany. At a T/R ratio of 1.37, True Mahogany 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 | 7 lb |
| 1×6 × 8′ | 4 bd ft | 10.5 lb |
| 1×8 × 8′ | 5.33 bd ft | 14 lb |
| 1×10 × 8′ | 6.67 bd ft | 17.4 lb |
| 1×12 × 8′ | 8 bd ft | 20.9 lb |
| 2×4 × 8′ | 5.33 bd ft | 14 lb |
| 2×6 × 8′ | 8 bd ft | 20.9 lb |
| 2×8 × 8′ | 10.67 bd ft | 27.9 lb |
Different length or size? Run the board foot calculator or the weight calculator, both preloaded with True 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 | 0.075″ (≈ 1/16 in) |
| Chicago, IL | May · 12.3% | Dec · 15.1% | 2.8 pts | 0.046″ (≈ 1/32 in) |
| Miami, FL | Apr · 12.2% | Sep · 14.4% | 2.2 pts | 0.036″ (≈ 1/32 in) |
| Boston, MA | Apr · 11.5% | Sep · 12.8% | 1.3 pts | 0.021″ (≈ 1/32 in) |
| Denver, CO | Jul · 8% | Dec · 10.5% | 2.5 pts | 0.041″ (≈ 1/32 in) |
| Seattle, WA | Jul · 12% | Dec · 16.9% | 4.9 pts | 0.08″ (≈ 3/32 in) |
Driven by True Mahogany's tangential shrinkage of 4.1%. These are outdoor equilibrium-moisture figures, so they are an upper bound — a climate-controlled interior swings less. How this is calculated.
How True Mahogany compares
Ranked against the 196 species in the Wood Handbook tables this site carries.
- Hardness: at 800 lbf, True Mahogany is harder than 41% of the 157 species with a Janka figure.
- Weight: at 31.4 lb/ft³ it is heavier than 30% of the 170 species measured — an 8-foot 1×6 board weighs about 10.5 lb.
- Stability: its T/R ratio of 1.37 is more even than 94% of the 196 species here — as humidity changes, 6% of them hold their shape more evenly.
See True 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 True Mahogany is unavailable or priced out.
- Eastern Redcedar is a common substitute for True Mahogany : 19% softer, about the same weight, and less stable in service.
- Spanish-cedar is a common substitute for True Mahogany : 25% softer, 9% lighter, and similarly stable in service.
- Black Ash is a common substitute for True Mahogany : nearly identical hardness, 9% heavier, and less stable in service.
- Coast Douglas-fir is a common substitute for True Mahogany : 11% softer, about the same weight, and less stable in service.
| Species | Janka | Density | T/R |
|---|---|---|---|
| Eastern Redcedar | 650 lbf | 32.8 | 1.52 |
| Spanish-cedar | 600 lbf | 28.7 | 1.5 |
| Black Ash | 850 lbf | 34.2 | 1.56 |
| Coast Douglas-fir | 710 lbf | 33.5 | 1.58 |
About True Mahogany
The name mahogany is presently applied to several distinct kinds of commercial wood. The original mahogany wood, produced by Swietenia mahagoni, came from the American West Indies. This was the premier wood for fine furniture cabinet work and shipbuilding in Europe as early as the 1600s. Because the good reputation associated with the name mahogany is based on this wood, American mahogany is sometimes referred to as true mahogany. A related African wood, of the genus Khaya, has long been marketed as “African mahogany” and is used for much the same purposes as American mahogany because of its similar properties and overall appearance. A third kind of wood called mahogany, and the one most commonly encountered in the market, is “Philippine mahogany.” This name is applied to a group of Asian woods belonging to the genus Shorea. In this chapter, information on the “Philippine mahoganies” is given under lauan and meranti groups.
Durability & sustainability
CITES status: True Mahogany is listed on CITES Appendix II, which restricts international trade. Big-leaf mahogany (Swietenia macrophylla) -- the species the Wood Handbook calls simply “mahogany” -- has been listed on CITES Appendix II since 2003.
Properties
| Specific gravity | 0.45 |
|---|---|
| Janka hardness (side) | 800 lbf |
| Density (air-dry, 12% MC) | 31.4 lb/ft³ (503 kg/m³) ovendry-weight basis: 28.1 lb/ft³ |
| Weight per board foot (air-dry) | 2.62 lb |
| Radial shrinkage (green→oven-dry) | 3% |
| Tangential shrinkage (green→oven-dry) | 4.1% |
| Volumetric shrinkage (green→oven-dry) | 7.8% |
| T/R ratio (stability indicator) | 1.4 |
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.