Jarrah (Eucalyptus marginata) in numbers: hardness, weight, strength, shrinkage, movement and decay resistance, taken from the tables of the USDA Forest Products Laboratory’s Wood Handbook, followed by what the wood is like to work and what it is used for. The values are averages from small, clear, straight-grained test specimens; real boards with knots, sloping grain or a different moisture content will differ.
| Property | Jarrah |
|---|---|
| Janka side hardness, 12% moisture | 1,910 lbf (8,496 N) |
| Janka side hardness, green | 1,290 lbf |
| Hardness rank | harder than 145 of the 168 woods with a 12% hardness value in our database |
| Density at 12% moisture | 54.0 lb/ft³ (865 kg/m³)† |
| Weight per board foot (12%) | 4.50 lb† |
| Specific gravity (ovendry weight, green volume) | 0.67 |
| Specific gravity at 12% moisture | 0.77† |
| Bending strength (modulus of rupture), 12% | 16,200 psi |
| Stiffness (modulus of elasticity), 12% | 1.88 million psi |
| Crushing strength (compression parallel to grain), 12% | 8,870 psi |
| Shrinkage green to ovendry: radial / tangential / volumetric | 7.7% / 11.0% / 18.7% |
| Tangential / radial shrinkage ratio | 1.43 |
| Dimensional change per 1% moisture (radial / tangential) | not reported |
| Heartwood decay resistance | very resistant |
What it is
Jarrah (Eucalyptus marginata) is native to the coastal belt of south-western Australia and is one of the main species of that country’s sawmill industry. The heartwood is a uniform pink to dark red that often turns a deep brownish red with age and exposure to air. In old trees the sapwood is pale and usually very narrow.
The texture is even and moderately coarse, and the grain is frequently interlocked or wavy. The Handbook names gum veins or gum pockets as its common defect; in extreme cases they split a log into concentric shells. Its close relative karri (E. diversicolor) looks similar but is usually paler and slightly heavier.
Working properties
Jarrah is a heavy, hard timber with correspondingly high strength. That density, together with the irregular grain, makes it difficult to work with hand and machine tools: use sharp carbide tooling, pre-drill for every screw and nail, and expect tear-out on interlocked boards.
It also moves a lot. Volumetric shrinkage from green to ovendry is about 18.7%, among the ten highest of the 179 woods with a shrinkage value in our database, so jarrah should be dried properly and acclimatised before installation, and decking needs generous gaps. The heartwood is resistant to termites and in the very resistant decay class of Table 14-1.
Weight and density
At 12% moisture content jarrah weighs about 54.0 lb per cubic foot (estimated from its specific gravity and shrinkage), so one board foot (144 cubic inches) weighs about 4.50 lb. An 8 ft board of actual size 3/4 × 5-1/2 in. (a 1×6) holds 0.229 cubic feet and weighs about 12.4 lb; an 8 ft piece 1-1/2 × 3-1/2 in. (a 2×4 size) weighs about 15.8 lb. Green wood is much heavier because of the water it holds.
Density here is ovendry weight plus 12% water, divided by volume at 12% moisture content (Wood Handbook Eq. 4-12: density = specific gravity at 12% × 62.43 lb/ft³ × 1.12).
How it compares
| Species | Janka (lbf) | Density (lb/ft³) | Bending (psi) | Stiffness (Mpsi) | Tangential shrink (%) | Decay resistance |
|---|---|---|---|---|---|---|
| Jarrah | 1,910 | 54.0† | 16,200 | 1.88 | 11.0 | very resistant |
| Karri | 2,040 | 65.2* | 20,160 | 2.6 | 12.4 | resistant |
| Ipe | 3,680 | 64.0† | 25,400 | 3.14 | 8.0 | very resistant |
| Courbaril (jatoba) | 2,350 | 53.8* | 19,400 | 2.16 | 8.5 | resistant |
| White oak | 1,360 | 47.5 | 15,200 | 1.78 | 10.5 | resistant |
| Teak | 1,000 | 40.1* | 14,600 | 1.55 | 5.8 | very resistant (old growth); moderately resistant (young growth) |
Uses
The Handbook lists decking and underframing of piers, jetties and bridges, piles and fenders for docks and harbours, railroad crossties and other heavy construction. As flooring jarrah has high resistance to wear, but it tends to splinter under heavy traffic. In Australia it is also a classic furniture and decking timber, and recycled jarrah from old buildings is sold as reclaimed stock.
Frequently asked questions
How hard is jarrah?
Jarrah has a Janka side hardness of 1,910 lbf (8,496 N) at 12% moisture content in the Wood Handbook, about 1.4 times that of white oak.
Is jarrah good for decking?
Yes. Its heartwood is very resistant to decay and resistant to termites, and it is traditionally used for jetty and bridge decks. Allow for its high shrinkage with wider gaps, and pre-drill fixings.
How heavy is jarrah?
About 54.0 lb per cubic foot at 12% moisture content, or 4.50 lb per board foot.
What is the difference between jarrah and karri?
Both are south-west Australian eucalypts with similar structure. The Handbook describes karri as usually paler and, on average, slightly heavier than jarrah.
Sources
- USDA Forest Products Laboratory. Wood Handbook: Wood as an Engineering Material. General Technical Report FPL-GTR-190, 2010. Chapter 2 (species descriptions), Chapter 4 (Tables 4-3, 4-4 shrinkage; Eq. 4-7, 4-9, 4-12 density), Chapter 5 (Tables 5-3b, 5-5b strength and hardness), Chapter 13 (Table 13-5 dimensional change coefficients), Chapter 14 (Table 14-1 decay resistance)
- USDA Forest Products Laboratory. Wood Handbook, 2021 edition (FPL-GTR-282)
Last reviewed: 24 October 2026. Numbers are generated from our parsed copy of the Handbook tables, so every page uses the same data. Values marked * are estimates computed with the Handbook’s own equations. Spotted an error? Please let us know.