Jarrah wood movement, board-foot & weight calculator
- Janka
- 1,910lbf
- Density
- 46.8lb/ft³
- T/R ratio
- 1.4
- Spec. gravity
- 0.67
Jarrah (Eucalyptus marginata) is an imported species. It has a Janka side hardness of 1,910 lbf, a specific gravity of 0.67, and an air-dry density near 47 lb/ft³ (750 kg/m³) (mechanical values at 12% moisture content). It shrinks 11% tangentially and 7.7% radially from green to oven-dry (T/R ratio 1.4), so a 12-inch flatsawn board moves about 0.26 in (≈ 1/4 in) across a 6-point moisture swing (about 6%→12% MC).
Compute Jarrah: movement, weight & board footage
Every number below is worked from Jarrah'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″ | 0.044″ (≈ 1/32 in) | 0.031″ (≈ 1/32 in) |
| 3″ | 0.066″ (≈ 1/16 in) | 0.046″ (≈ 1/32 in) |
| 4″ | 0.088″ (≈ 3/32 in) | 0.062″ (≈ 1/16 in) |
| 6″ | 0.132″ (≈ 1/8 in) | 0.092″ (≈ 3/32 in) |
| 8″ | 0.176″ (≈ 3/16 in) | 0.123″ (≈ 1/8 in) |
| 10″ | 0.22″ (≈ 7/32 in) | 0.154″ (≈ 5/32 in) |
| 12″ | 0.264″ (≈ 1/4 in) | 0.185″ (≈ 3/16 in) |
| 16″ | 0.352″ (≈ 11/32 in) | 0.246″ (≈ 1/4 in) |
Need a different width or moisture swing? Run the movement calculator preloaded with Jarrah. At a T/R ratio of 1.43, Jarrah 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 | 10.4 lb |
| 1×6 × 8′ | 4 bd ft | 15.6 lb |
| 1×8 × 8′ | 5.33 bd ft | 20.8 lb |
| 1×10 × 8′ | 6.67 bd ft | 26 lb |
| 1×12 × 8′ | 8 bd ft | 31.2 lb |
| 2×4 × 8′ | 5.33 bd ft | 20.8 lb |
| 2×6 × 8′ | 8 bd ft | 31.2 lb |
| 2×8 × 8′ | 10.67 bd ft | 41.6 lb |
Different length or size? Run the board foot calculator or the weight calculator, both preloaded with Jarrah.
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 | 0.202″ (≈ 3/16 in) |
| Chicago, IL | May · 12.3% | Dec · 15.1% | 2.8 pts | 0.123″ (≈ 1/8 in) |
| Miami, FL | Apr · 12.2% | Sep · 14.4% | 2.2 pts | 0.097″ (≈ 3/32 in) |
| Boston, MA | Apr · 11.5% | Sep · 12.8% | 1.3 pts | 0.057″ (≈ 1/16 in) |
| Denver, CO | Jul · 8% | Dec · 10.5% | 2.5 pts | 0.11″ (≈ 1/8 in) |
| Seattle, WA | Jul · 12% | Dec · 16.9% | 4.9 pts | 0.216″ (≈ 7/32 in) |
Driven by Jarrah's tangential shrinkage of 11%. These are outdoor equilibrium-moisture figures, so they are an upper bound — a climate-controlled interior swings less. How this is calculated.
How Jarrah compares
Ranked against the 196 species in the Wood Handbook tables this site carries.
- Hardness: at 1,910 lbf, Jarrah is harder than 87% of the 157 species with a Janka figure — firmly in the hard quarter, which is what resists denting in flooring and worktops.
- Weight: at 46.8 lb/ft³ it is heavier than 79% of the 170 species measured — an 8-foot 1×6 board weighs about 15.6 lb.
- Stability: its T/R ratio of 1.43 is more even than 89% of the 196 species here — as humidity changes, 11% of them hold their shape more evenly.
See Jarrah 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 Jarrah is unavailable or priced out.
- Shagbark Hickory is a common substitute for Jarrah : nearly identical hardness, about the same weight, and similarly stable in service.
- Black Locust is a common substitute for Jarrah : 11% softer, about the same weight, and similarly stable in service.
- Honeylocust is a common substitute for Jarrah : 17% softer, 10% lighter, and similarly stable in service.
| Species | Janka | Density | T/R |
|---|---|---|---|
| Shagbark Hickory | 1,880 lbf | 50.3 | 1.5 |
| Black Locust | 1,700 lbf | 48.2 | 1.57 |
| Honeylocust | 1,580 lbf | 41.9 | 1.57 |
About Jarrah
Jarrah (Eucalyptus marginata) is native to the coastal belt of southwestern Australia and is one of the principal species for that country’s sawmill industry. The heartwood is a uniform pink to dark red, often turning to deep brownish red with age and exposure to air. The sapwood is pale and usually very narrow in old trees. The texture is even and moderately coarse, and the grain is frequently interlocked or wavy. The wood weighs about 865 kg m–3 (54 lb ft–3) at 12% moisture content. The common defects of jarrah include gum veins or pockets, which in extreme instances separate the log into concentric shells. Jarrah is a heavy, hard timber possessing correspondingly high strength properties. It is resistant to attack by termites and rated as very durable with respect to decay. The wood is difficult to work with hand and machine tools because of its high density and irregular grain. Jarrah is used for decking and underframing of piers, jetties, and bridges, as well as piles and fenders for docks and harbors. As flooring, jarrah has high resistance to wear, but it is inclined to splinter under heavy traffic. It is also used for railroad crossties and other heavy construction.
Durability & sustainability
Decay resistance: the Wood Handbook rates Jarrah heartwood very 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 | 0.67 |
|---|---|
| Janka hardness (side) | 1,910 lbf |
| Density (air-dry, 12% MC) | 46.8 lb/ft³ (750 kg/m³) ovendry-weight basis: 41.8 lb/ft³ |
| Weight per board foot (air-dry) | 3.9 lb |
| Radial shrinkage (green→oven-dry) | 7.7% |
| Tangential shrinkage (green→oven-dry) | 11% |
| Volumetric shrinkage (green→oven-dry) | 18.7% |
| 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.