What is Young’s modulus of wood?

Young’s modulus (E) quantifies stiffness. For wood, EL is measured along the grain and is much higher than across the grain (radial or tangential).

Why do values differ between “green” and 12% moisture content?

Moisture content strongly affects stiffness—higher moisture lowers E; drying to ~12% MC increases E.

How do I convert MPa to psi?

Multiply MPa by 145.038 to obtain psi; divide by 1,000,000 to express in 10^6 psi.

AMESWEB

YOUNG'S MODULUS (MODULUS OF ELASTICITY) OF WOOD

Average Young’s modulus values of wood along the longitudinal axis (E_L) from bending tests are listed below. Values are shown for green and 12% moisture content conditions, in MPa and in 10⁶ psi.

Young's Modulus of Wood (illustrative graphic)

Young’s Modulus of Wood (E) – 12% Moisture Content
Species	E (MPa)	E (10⁶ psi)
Hardwoods
Ash, white	12000	1.74
Beech, American	11900	1.72
Birch, yellow	13900	2.01
Hickory, shagbark	14900	2.16
Maple, sugar	12600	1.83
Oak, red (northern)	12500	1.82
Oak, white	12300	1.78
Walnut, black	11600	1.68
Softwoods
Douglas-fir, coast	13400	1.95
Douglas-fir, interior north	12300	1.79
Pine, eastern white	8500	1.24
Pine, red	11200	1.63
Pine, shortleaf	12100	1.75
Spruce, sitka	10800	1.57
Spruce, white	9600	1.43
Notes: • Values are typical averages determined from bending tests along the grain (longitudinal axis). • For design use, refer to applicable standards (ASTM/ASME). • Modulus of elasticity may vary with temperature, moisture, and direction.

Notes: Average coefficient of variation for E_L is about 22% based on bending tests of clear & green wood from ~50 species. Values adjusted to 12% moisture content are of comparable magnitude. Because these values are obtained from bending, shear deflection slightly influences the result; increasing E_L by ≈10% gives an approximate correction for shear.

Average values along the tangential (E_T) and radial (E_R) axes for selected species appear below as ratios to E_L.

Elastic Ratios of Wood (E_T/E_L and E_R/E_L) — 12% Moisture Content
Species	E_T/E_L	E_R/E_L
Hardwoods
Ash, white	0.080	0.125
Basswood, American	0.027	0.066
Birch, yellow	0.050	0.078
Cherry, black	0.086	0.197
Cottonwood, eastern	0.047	0.083
Maple, sugar	0.065	0.132
Oak, red	0.082	0.154
Oak, white	0.072	0.163
Sweetgum	0.050	0.115
Walnut, black	0.056	0.106
Softwoods
Baldcypress	0.039	0.084
Cedar, northern white	0.081	0.183
Cedar, western red	0.055	0.081
Douglas-fir	0.050	0.068
Hemlock, western	0.031	0.058
Larch, western	0.065	0.079
Pine, ponderosa	0.083	0.122
Pine, red	0.044	0.088
Pine, western white	0.038	0.078
Redwood	0.089	0.087
Spruce, sitka	0.043	0.078
Spruce, Engelmann	0.059	0.128
Notes: • Ratios show relative stiffness across the grain vs. along the grain. • E_T = tangential modulus, E_R = radial modulus, E_L = longitudinal modulus. • Typical variability ±20%. Values representative for clear wood at ~12% moisture.

Reference

Wood Handbook: Wood as an Engineering Material. USDA Forest Service, Forest Products Laboratory, 2010.
Baumeister, T. et al. Marks' Standard Handbook for Mechanical Engineers. McGraw-Hill, 2007.
Oberg, E., Jones, F.D., Horton, H.L., Ryffel, H.H. Machinery’s Handbook. 30th ed., Industrial Press, 2016.

Frequently Asked Questions

Young’s modulus (E) describes the stiffness of a material in tension or compression. For wood, E_L is measured along the grain (longitudinal) and is much larger than across the grain (radial or tangential).

Moisture strongly affects stiffness. As moisture increases toward fiber saturation, E decreases; drying to ~12% MC typically increases E.

Multiply MPa by 145.038 to get psi. To express in “10⁶ psi”, divide the result by 1,000,000.