Hardwood vs softwood: what the numbers show
By Lucas Anderson · Published · Data: Wood Handbook 2010
On average, U.S. hardwoods are much harder than U.S. softwoods: the medians in the Wood Handbook data are 1,160 lbf and 500 lbf. For strength and stiffness the gap is far smaller, softwoods shrink less, and the ranges overlap: 33 of 37 U.S. softwoods are harder than the softest U.S. hardwoods.
What the labels mean
Hardwood and softwood are botanical groups. Hardwoods are broadleaved trees, softwoods are conifers. On average the label matches the hardness, but it is not a hardness grade. The handbook’s tables split the woods by origin as well: U.S. hardwoods (53 species here), U.S. softwoods (37) and imported woods (65). Most imports are hardwoods; three are softwoods (Caribbean pine, ocote pine and Parana-pine). This guide uses those three groups, the same ones as the hardwood, softwood and imported pages.
The medians side by side
| Median | U.S. hardwoods | U.S. softwoods | Imported |
|---|---|---|---|
| Janka hardness, lbf | 1,160 | 500 | 1,300 |
| Specific gravity | 0.52 | 0.38 | 0.61 |
| Bending strength, psi | 13,000 | 10,200 | 16,700 |
| Stiffness, M psi | 1.60 | 1.50 | 2.00 |
| Stiffness ÷ SG | 3.13 | 3.81 | 3.39 |
| Tangential shrinkage | 8.9% | 7.1% | 7.9% |
| Radial shrinkage | 4.8% | 3.8% | 4.5% |
| T/R ratio | 1.88 | 1.86 | 1.74 |
Hardness shows the widest gap. The median U.S. hardwood measures 1,160 lbf, 2.3 times the median U.S. softwood at 500 lbf. Density moves in the same direction, 0.52 against 0.38, which is expected given how closely density and hardness track each other (see density and hardness).
The other mechanical figures are much closer. Median bending strength is 13,000 psi for U.S. hardwoods and 10,200 psi for softwoods, a 27% difference. Stiffness differs by only 7%: 1.60 against 1.50 million psi. Divide stiffness by specific gravity and the order flips: softwoods have a median of 3.81 against 3.13 for hardwoods, so per unit of weight the typical conifer here is the stiffer material.
On movement, softwoods shrink less. Their median tangential shrinkage is 7.1% against 8.9% for U.S. hardwoods. The T/R ratio, which describes how evenly the wood moves, is nearly the same in both groups (1.86 and 1.88), so the gap is in the amount of shrinkage, not in its balance.
Where the groups overlap
U.S. hardwoods
53 species · median 1,160 lbf
U.S. softwoods
37 species · median 500 lbf
Imported woods
65 species · median 1,300 lbf
The strips show how much the ranges overlap. The softest U.S. hardwoods, black cottonwood and quaking aspen, measure 350 lbf. Of the 37 U.S. softwoods, 33 are harder than that. At the other end, five U.S. hardwoods fall below even the softwood median of 500 lbf: black cottonwood (350), quaking aspen (350), American basswood (410), eastern cottonwood (430) and butternut (490).
From the softwood side, longleaf pine at 870 lbf is harder than 17 of the 53 U.S. hardwoods, and Douglas-fir (Coast), at 710 lbf, beats 10 of them. The imported softwoods go further: Caribbean pine reaches 1,240 lbf, harder than any U.S. softwood and than 33 U.S. hardwoods.
Strength for the weight
Because softwoods are lighter, comparing them per unit of weight closes the gap. Bending strength divided by specific gravity has a median of 26,905 psi for U.S. softwoods and 25,625 psi for U.S. hardwoods. The highest strength-to-weight figure among U.S. woods belongs to Port-Orford-cedar (32,564 psi), a softwood. Every species page gives its own strength-to-weight and stiffness-to-weight figures with their ranks, and the rankings page lists the woods with the best stiffness for their weight.
The spread inside the big families is a reminder that the group label hides a lot. The 13 pines in the handbook run from 380 lbf to 1,240 lbf and the 15 oaks from 1,060 lbf to 2,500 lbf; the hardest pine is harder than the softest oak.
Why imports sit apart
The imported group has the highest medians for hardness (1,300 lbf), density (0.61), bending strength and stiffness. The group is a selection of woods imported into the United States, so its medians describe that selection, not tropical timber in general. The group also covers the full range, from ceiba at 240 lbf to ipe at 3,680 lbf. Its figures come from world literature rather than the Forest Products Laboratory’s own tests, according to the handbook, which is worth keeping in mind for small differences.
Reading a wood by its numbers
The label tells you which group a tree belongs to, and the group medians give a fair first guess. A single species can still land far from its group, so the numbers for that species are the better guide. Put a hardwood and a softwood side by side in the comparer, for example yellow-poplar and longleaf pine, and the “hardwood” turns out to be the softer of the two (540 lbf against 870 lbf). The finder can also be limited to one group at a time.
Sources and method
USDA Forest Service, Forest Products Laboratory. Wood Handbook: Wood as an Engineering Material (2010, FPL-GTR-190), Tables 4-3 and 4-4 (shrinkage) and 5-3b and 5-5b (strength and hardness). Public domain. Medians, counts, ranks, correlations and percentages are calculated by TimberLedger from those tables across the 155 woods on this site. Data as of: Wood Handbook 2010 edition (published test averages of small clear specimens). How we use the data.