Iroko (Chlorophora 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 | Iroko |
|---|---|
| Janka side hardness, 12% moisture | 1,260 lbf (5,605 N) |
| Janka side hardness, green | 1,080 lbf |
| Hardness rank | harder than 107 of the 168 woods with a 12% hardness value in our database |
| Density at 12% moisture | 39.9 lb/ft³ (638 kg/m³)* |
| Weight per board foot (12%) | 3.32 lb* |
| Specific gravity (ovendry weight, green volume) | 0.54 |
| Specific gravity at 12% moisture | 0.57* |
| Bending strength (modulus of rupture), 12% | 12,400 psi |
| Stiffness (modulus of elasticity), 12% | 1.46 million psi |
| Crushing strength (compression parallel to grain), 12% | 7,590 psi |
| Shrinkage green to ovendry: radial / tangential / volumetric | 2.8% / 3.8% / 8.8% |
| Tangential / radial shrinkage ratio | 1.36 |
| Dimensional change per 1% moisture (radial / tangential) | 0.00153 / 0.00205 |
| Heartwood decay resistance | resistant |
What it is
Iroko is the trade name for two African species, Milicia excelsa and M. regia (older books and our data table file them under Chlorophora). M. excelsa grows right across tropical Africa from the Ivory Coast south to Angola and east to East Africa; M. regia is limited to the far west, from Gambia to Ghana.
The heartwood ranges from pale yellowish brown to dark chocolate brown, with lighter markings that show most on flatsawn faces, and the sapwood is yellowish white. The texture is medium to coarse and the grain is typically interlocked. Because of its colour and durability, the Handbook notes that iroko has been suggested as a substitute for teak.
Working properties
Iroko works easily with hand or machine tools, but the interlocked grain tears in places, and occasional deposits of calcium carbonate (stone-like mineral inclusions) can badly damage cutting edges. Carbide tooling and a high cutting angle on the planer help. It dries rapidly with little or no degrade.
In strength the Handbook compares iroko to red maple. Its standout figure is stability: tangential shrinkage from green to ovendry is only 3.8%, the second lowest of the 179 woods with a shrinkage value in our database, which is a large part of why it suits joinery that sees changing humidity. The heartwood is in the resistant class of Table 14-1, and the species description calls it very resistant to decay fungi and resistant to termites and marine borers.
Weight and density
At 12% moisture content iroko weighs about 39.9 lb per cubic foot (estimated from its specific gravity and shrinkage), so one board foot (144 cubic inches) weighs about 3.32 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 9.1 lb; an 8 ft piece 1-1/2 × 3-1/2 in. (a 2×4 size) weighs about 11.6 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).
Wood movement
The Wood Handbook gives dimensional change coefficients for each species: the fraction of its width a board gains or loses for every 1% change in moisture content, between about 6% and 14%. For iroko they are 0.00205 across a flatsawn face (tangential) and 0.00153 across a quartersawn face (radial).
Worked example: a flatsawn board 7-1/4 in. wide (a nominal 1×8) that goes from 6% moisture content in a heated winter house to 12% in a humid summer changes width by 7.25 × 0.00205 × 6 = 0.089 in. (about 3/32 in.). The same board quartersawn moves 0.067 in. (about 1/16 in.). Allow for this in panels, tabletops and floors; the wood movement calculator works it out for any size and moisture range.
How it compares
| Species | Janka (lbf) | Density (lb/ft³) | Bending (psi) | Stiffness (Mpsi) | Tangential shrink (%) | Decay resistance |
|---|---|---|---|---|---|---|
| Iroko | 1,260 | 39.9* | 12,400 | 1.46 | 3.8 | resistant |
| Teak | 1,000 | 40.1* | 14,600 | 1.55 | 5.8 | very resistant (old growth); moderately resistant (young growth) |
| Genuine mahogany (Honduran / big-leaf) | 800 | 33.0* | 11,500 | 1.5 | 4.1 | resistant |
| Sapele | 1,510 | 42.0* | 15,300 | 1.82 | 7.4 | moderately resistant |
| White oak | 1,360 | 47.5 | 15,200 | 1.78 | 10.5 | resistant |
| Red maple | 950 | 37.8 | 13,400 | 1.64 | 8.2 | slightly or nonresistant |
Uses
Its durability makes iroko suitable for boat building, piles, other marine work and railroad crossties. It is also used for joinery, flooring, furniture, veneer and cabinetwork. In Britain and Europe it is a common choice for solid-wood kitchen worktops, window sills and outdoor benches, where it is usually oiled.
Frequently asked questions
Is iroko as good as teak?
For many outdoor and wet uses it is a reasonable substitute. In the Handbook data iroko is somewhat harder than teak (1,260 lbf against 1,000) and has similarly low shrinkage, and both have decay-resistant heartwood. Teak has a higher natural oil content and a finer, more even texture.
How hard is iroko?
The Wood Handbook gives iroko a Janka side hardness of 1,260 lbf (5,605 N) at 12% moisture content, about 0.9 times that of white oak.
Is iroko good for worktops?
Yes, it is widely used for them: it is stable, decay resistant and moderately hard. Seal the end grain around sinks and re-oil the surface regularly.
Why does iroko blunt tools?
Some logs contain calcium carbonate deposits in the wood. They are hard enough to chip or dull steel edges, so carbide blades and cutters are a better choice.
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.