Keruing (Dipterocarpus spp.) 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 | Keruing |
|---|---|
| Janka side hardness, 12% moisture | 1,270 lbf (5,649 N) |
| Janka side hardness, green | 1,060 lbf |
| Hardness rank | harder than 109 of the 168 woods with a 12% hardness value in our database |
| Density at 12% moisture | 53.4 lb/ft³ (856 kg/m³)* |
| Weight per board foot (12%) | 4.45 lb* |
| Specific gravity (ovendry weight, green volume) | 0.69 |
| Specific gravity at 12% moisture | 0.76* |
| Bending strength (modulus of rupture), 12% | 19,900 psi |
| Stiffness (modulus of elasticity), 12% | 2.07 million psi |
| Crushing strength (compression parallel to grain), 12% | 10,500 psi |
| Shrinkage green to ovendry: radial / tangential / volumetric | 5.2% / 10.9% / 16.1% |
| Tangential / radial shrinkage ratio | 2.1 |
| Dimensional change per 1% moisture (radial / tangential) | not reported |
| Heartwood decay resistance | moderately resistant |
What it is
Keruing is the trade name for most of the more than 70 species of Dipterocarpus, which grow widely across the Indo-Malaysian region. Related species are marketed as apitong in the Philippines and yang in Thailand. The heartwood ranges from light to dark red-brown or brown, sometimes with a purple tint, and is usually well defined from the grey or buff sapwood.
The texture is moderately coarse and the grain straight or shallowly interlocked. On end grain you can see resin ducts, single or in short arcs, which are the key to how it behaves in the shop.
Working properties
Keruing is strong, hard and heavy. In our data its bending strength of 19,900 psi is higher than white oak’s, and its stiffness is 2.07 million psi. It saws and machines reasonably well, particularly when green, but its high silica content dulls saws and cutters quickly, and resin sticks to blades and machinery and can cause gluing and finishing problems.
Durability varies by species, and the Handbook classes keruing as moderately durable (moderately resistant in Table 14-1). Sapwood and heartwood are moderately resistant to preservatives, but it should be treated when used in contact with the ground. Shrinkage is high across the grain, about 10.9% tangentially.
Weight and density
At 12% moisture content keruing weighs about 53.4 lb per cubic foot (estimated from its specific gravity and shrinkage), so one board foot (144 cubic inches) weighs about 4.45 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 12.2 lb; an 8 ft piece 1-1/2 × 3-1/2 in. (a 2×4 size) weighs about 15.6 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 |
|---|---|---|---|---|---|---|
| Keruing | 1,270 | 53.4* | 19,900 | 2.07 | 10.9 | moderately resistant |
| Kempas | 1,710 | 55.0† | 17,700 | 2.69 | 7.4 | resistant |
| White oak | 1,360 | 47.5 | 15,200 | 1.78 | 10.5 | resistant |
| Courbaril (jatoba) | 2,350 | 53.8* | 19,400 | 2.16 | 8.5 | resistant |
| Light red meranti | 460 | 26.0* | 9,500 | 1.23 | 8.5 | slightly or nonresistant |
| Longleaf pine | 870 | 41.3 | 14,500 | 1.98 | 7.5 | moderately resistant (old growth only); otherwise slightly or nonresistant |
Uses
Keruing is used for general construction, framework for boats, flooring, pallets, chemical processing equipment, veneer and plywood, treated railroad crossties, truck floors and boardwalks. Apitong truck and trailer flooring is one of its best-known uses in North America.
Frequently asked questions
Is apitong the same as keruing?
They are species of the same genus, Dipterocarpus. The Handbook covers them together: keruing in Malaysia and Indonesia, apitong in the Philippines.
Why is keruing used for trailer floors?
It is strong, hard and heavy, with bending strength of 19,900 psi in the Handbook data, and it is heavy and hard enough to take forklift and cargo wear. Treated, it holds up in heavy-duty decks.
Is keruing hard to work?
It machines well, but silica dulls tools fast and its resin gums up blades and can interfere with glue and finishes.
Is keruing rot resistant?
Only moderately. Treat it with preservative for ground contact, as the Handbook advises.
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.