Merbau wood movement calculator
- Janka
- —
- Density
- —
- T/R ratio
- 1.7
- Spec. gravity
- —
Merbau (Intsia bijuga and I. palembanica) is an imported species. The Wood Handbook strength tables list no matched specific gravity or hardness for it, so those fields are shown as “—”. It shrinks 4.6% tangentially and 2.7% radially from green to oven-dry (T/R ratio 1.7), so a 12-inch flatsawn board moves about 0.11 in (≈ 1/8 in) across a 6-point moisture swing (about 6%→12% MC).
Compute Merbau: movement, weight & board footage
Every number below is worked from Merbau'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) | 0.011″ (≈ 0 in) |
| 3″ | 0.028″ (≈ 1/32 in) | 0.016″ (≈ 1/32 in) |
| 4″ | 0.037″ (≈ 1/32 in) | 0.022″ (≈ 1/32 in) |
| 6″ | 0.055″ (≈ 1/16 in) | 0.032″ (≈ 1/32 in) |
| 8″ | 0.074″ (≈ 1/16 in) | 0.043″ (≈ 1/32 in) |
| 10″ | 0.092″ (≈ 3/32 in) | 0.054″ (≈ 1/16 in) |
| 12″ | 0.11″ (≈ 1/8 in) | 0.065″ (≈ 1/16 in) |
| 16″ | 0.147″ (≈ 5/32 in) | 0.086″ (≈ 3/32 in) |
Need a different width or moisture swing? Run the movement calculator preloaded with Merbau. At a T/R ratio of 1.7, Merbau 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 and weight aren't shown for Merbau — the Wood Handbook strength tables carry no matched density for it, so a weight figure here would be invented rather than computed. The board foot calculator still works without a species; board feet don't depend on density.
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 | 0.085″ (≈ 3/32 in) |
| Chicago, IL | May · 12.3% | Dec · 15.1% | 2.8 pts | 0.052″ (≈ 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 | 0.024″ (≈ 1/32 in) |
| Denver, CO | Jul · 8% | Dec · 10.5% | 2.5 pts | 0.046″ (≈ 1/32 in) |
| Seattle, WA | Jul · 12% | Dec · 16.9% | 4.9 pts | 0.09″ (≈ 3/32 in) |
Driven by Merbau's tangential shrinkage of 4.6%. These are outdoor equilibrium-moisture figures, so they are an upper bound — a climate-controlled interior swings less. How this is calculated.
How Merbau compares
Ranked against the 196 species in the Wood Handbook tables this site carries.
- Stability: its T/R ratio of 1.7 is more even than 61% of the 196 species here — as humidity changes, 39% of them hold their shape more evenly.
About Merbau
Merbau (Malaysia), ipil (Philippines), and kwila (New Guinea) are names applied to species of the genus Intsia, most commonly I. bijuga. Intsia is distributed throughout the Indo– Malaysian region, Indonesia, Philippines, and many western Pacific islands, as well as Australia. Freshly cut yellowish to orange–brown heartwood turns brown or dark red–brown on exposure to air. The texture is rather coarse, and the grain is straight to interlocked or wavy. The strength of air-dried merbau is comparable with that of hickory (Carya), but density is somewhat lower (800 kg m–3 (50 lb ft–3) at 12% moisture content). The wood dries well with little degrade but stains black in the presence of iron and moisture. Merbau is rather difficult to saw because it sticks to saw teeth and dulls cutting edges. However, the wood dresses smoothly in most operations and finishes well. Merbau has good durability and high resistance to termite attack. The heartwood resists treatment, but the sapwood can be treated with preservatives. Merbau is used in furniture, fine joinery, turnery, cabinets, flooring, musical instruments, and specialty items.
Properties
| Specific gravity | — |
|---|---|
| Janka hardness (side) | — |
| Density (air-dry, 12% MC) | — |
| Weight per board foot (air-dry) | — |
| Radial shrinkage (green→oven-dry) | 2.7% |
| Tangential shrinkage (green→oven-dry) | 4.6% |
| Volumetric shrinkage (green→oven-dry) | 7.8% |
| T/R ratio (stability indicator) | 1.7 |
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. Values shown as “—” have no matched entry in the Wood Handbook strength tables (5-3b/5-5b).
Data: USDA Forest Products Laboratory, Wood Handbook FPL-GTR-282 (2021), public domain.