Balsa (Ochroma pyramidale) 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 | Balsa |
|---|---|
| Janka side hardness, 12% moisture | not reported |
| Janka side hardness, green | not reported |
| Density at 12% moisture | 12.0 lb/ft³ (192 kg/m³)* |
| Weight per board foot (12%) | 1.00 lb* |
| Specific gravity (ovendry weight, green volume) | 0.16 |
| Specific gravity at 12% moisture | 0.17* |
| Bending strength (modulus of rupture), 12% | 3,140 psi |
| Stiffness (modulus of elasticity), 12% | 0.49 million psi |
| Crushing strength (compression parallel to grain), 12% | 2,160 psi |
| Shrinkage green to ovendry: radial / tangential / volumetric | 3.0% / 7.6% / 10.8% |
| Tangential / radial shrinkage ratio | 2.53 |
| Dimensional change per 1% moisture (radial / tangential) | 0.00102 / 0.00267 |
| Heartwood decay resistance | slightly or nonresistant |
What it is
Balsa (Ochroma pyramidale) is widely distributed throughout tropical America from southern Mexico to southern Brazil and Bolivia, but Ecuador has been the principal source since the wood gained commercial importance. It usually grows at lower elevations, especially on bottom-land soils along streams and in clearings and cutover forests, and today it is often cultivated in plantations.
The Handbook calls balsa “the lightest and softest of all woods on the market”. It is easy to recognize by its light weight, its nearly white or oatmeal color, often with a yellowish or pinkish hue, and its unique velvety feel.
Working properties
The density of balsa in our table is estimated from its specific gravity and shrinkage. The Handbook’s description puts the balsa lumber selected for use in the United States a little lighter than that on average when dry, and says it is often much lighter still. The property tables give no hardness value for balsa. Its bending strength, stiffness and crushing strength are the lowest of any species in our database, and Table 14-1 puts its heartwood in the slightly or nonresistant decay class.
Weight and density
At 12% moisture content balsa weighs about 12.0 lb per cubic foot (estimated from its specific gravity and shrinkage), so one board foot (144 cubic inches) weighs about 1.00 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 2.8 lb; an 8 ft piece 1-1/2 × 3-1/2 in. (a 2×4 size) weighs about 3.5 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 balsa they are 0.00267 across a flatsawn face (tangential) and 0.00102 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 × 0.00267 × 6 = 0.116 in. (about 1/8 in.). The same board quartersawn moves 0.044 in. (about 1/32 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 |
|---|---|---|---|---|---|---|
| Balsa | — | 12.0* | 3,140 | 0.49 | 7.6 | slightly or nonresistant |
| Western redcedar | 350 | 22.4 | 7,500 | 1.11 | 5.0 | resistant |
| Eastern white pine | 380 | 24.5 | 8,600 | 1.24 | 6.1 | moderately resistant (old growth only); otherwise slightly or nonresistant |
| American basswood | 410 | 25.9 | 8,700 | 1.46 | 9.3 | slightly or nonresistant |
| Quaking aspen | 350 | 26.6 | 8,400 | 1.18 | 6.7 | slightly or nonresistant |
| Subalpine fir | 350 | 22.4 | 8,600 | 1.29 | 7.4 | slightly or nonresistant |
Uses
Its light weight and exceedingly porous composition make balsa highly efficient where buoyancy, insulation against heat or cold, or low transmission of sound and vibration are important. The principal uses are life-saving equipment, floats, rafts, corestock, insulation, cushioning, sound modifiers, models and novelties.
Frequently asked questions
How much does balsa wood weigh?
We estimate about 12.0 lb per cubic foot at 12% moisture content (1.00 lb per board foot), from its specific gravity. The Handbook says the balsa lumber selected for use in the United States averages a little less than that when dry, and is often much lighter.
Is balsa the lightest wood?
The Wood Handbook describes balsa as the lightest and softest of all woods on the market, and it is the lightest species in our database.
How hard is balsa?
The Handbook’s tables give no Janka hardness value for balsa, but its species description calls it the softest of all woods on the market.
Why is balsa used for floats and insulation?
Its light weight and exceedingly porous composition make it highly efficient where buoyancy, insulation against heat or cold, or low transmission of sound and vibration matter.
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.