Sitka Spruce wood movement, board-foot & weight calculator
- Janka
- 510lbf
- Density
- 28lb/ft³
- T/R ratio
- 1.7
- Spec. gravity
- 0.4
Sitka Spruce is a North American softwood. It has a Janka side hardness of 510 lbf, a specific gravity of 0.4, and an air-dry density near 28 lb/ft³ (449 kg/m³) (mechanical values at 12% moisture content). It shrinks 7.5% tangentially and 4.3% radially from green to oven-dry (T/R ratio 1.7), so a 12-inch flatsawn board moves about 0.18 in (≈ 3/16 in) across a 6-point moisture swing (about 6%→12% MC).
Compute Sitka Spruce: movement, weight & board footage
Every number below is worked from Sitka Spruce's own shrinkage and density figures, not looked up from a table — change the width, moisture swing, or board size in the calculators linked alongside.
Cross-grain movement by board width
| Board width | Flatsawn (tangential) | Quartersawn (radial) |
|---|---|---|
| 2″ | 0.03″ (≈ 1/32 in) | 0.017″ (≈ 1/32 in) |
| 3″ | 0.045″ (≈ 1/32 in) | 0.026″ (≈ 1/32 in) |
| 4″ | 0.06″ (≈ 1/16 in) | 0.034″ (≈ 1/32 in) |
| 6″ | 0.09″ (≈ 3/32 in) | 0.052″ (≈ 1/16 in) |
| 8″ | 0.12″ (≈ 1/8 in) | 0.069″ (≈ 1/16 in) |
| 10″ | 0.15″ (≈ 5/32 in) | 0.086″ (≈ 3/32 in) |
| 12″ | 0.18″ (≈ 3/16 in) | 0.103″ (≈ 3/32 in) |
| 16″ | 0.24″ (≈ 1/4 in) | 0.138″ (≈ 1/8 in) |
Need a different width or moisture swing? Run the movement calculator preloaded with Sitka Spruce. At a T/R ratio of 1.74, Sitka Spruce is stable — it moves moderately more across the face than through the thickness — normal behaviour for a furniture hardwood, and predictable if boards are acclimatised before milling.
Board footage & weight, standard sizes
| Nominal size × length | Board feet | Weight |
|---|---|---|
| 1×4 × 8′ | 2.67 bd ft | 6.2 lb |
| 1×6 × 8′ | 4 bd ft | 9.3 lb |
| 1×8 × 8′ | 5.33 bd ft | 12.4 lb |
| 1×10 × 8′ | 6.67 bd ft | 15.6 lb |
| 1×12 × 8′ | 8 bd ft | 18.7 lb |
| 2×4 × 8′ | 5.33 bd ft | 12.4 lb |
| 2×6 × 8′ | 8 bd ft | 18.7 lb |
| 2×8 × 8′ | 10.67 bd ft | 24.9 lb |
Different length or size? Run the board foot calculator or the weight calculator, both preloaded with Sitka Spruce.
Seasonal movement by city
| City | Driest month (EMC) | Most-humid month (EMC) | EMC swing | 12″ board movement |
|---|---|---|---|---|
| Phoenix, AZ | Jun · 4.4% | Dec · 9% | 4.6 pts | 0.138″ (≈ 1/8 in) |
| Chicago, IL | May · 12.3% | Dec · 15.1% | 2.8 pts | 0.084″ (≈ 3/32 in) |
| Miami, FL | Apr · 12.2% | Sep · 14.4% | 2.2 pts | 0.066″ (≈ 1/16 in) |
| Boston, MA | Apr · 11.5% | Sep · 12.8% | 1.3 pts | 0.039″ (≈ 1/32 in) |
| Denver, CO | Jul · 8% | Dec · 10.5% | 2.5 pts | 0.075″ (≈ 1/16 in) |
| Seattle, WA | Jul · 12% | Dec · 16.9% | 4.9 pts | 0.147″ (≈ 5/32 in) |
Driven by Sitka Spruce's tangential shrinkage of 7.5%. These are outdoor equilibrium-moisture figures, so they are an upper bound — a climate-controlled interior swings less. How this is calculated.
How Sitka Spruce compares
Ranked against the 196 species in the Wood Handbook tables this site carries.
- Hardness: at 510 lbf, Sitka Spruce is harder than 20% of the 157 species with a Janka figure — one of the softer woods here, easy to work and easy to dent.
- Weight: at 28 lb/ft³ it is heavier than 18% of the 170 species measured — an 8-foot 1×6 board weighs about 9.3 lb.
- Stability: its T/R ratio of 1.74 is more even than 58% of the 196 species here — as humidity changes, 42% of them hold their shape more evenly.
See Sitka Spruce plotted against every species we carry: the full Janka hardness chart and the full density chart .
Species with a similar working profile
Closest matches on hardness, weight and stability together — useful when Sitka Spruce is unavailable or priced out.
- Old Growth Redwood is a common substitute for Sitka Spruce : nearly identical hardness, about the same weight, and similarly stable in service.
- Yellow-poplar is a common substitute for Sitka Spruce : nearly identical hardness, about the same weight, and similarly stable in service.
- Red Alder is a common substitute for Sitka Spruce : 16% harder, about the same weight, and similarly stable in service.
- Butternut is a common substitute for Sitka Spruce : nearly identical hardness, about the same weight, and similarly stable in service.
| Species | Janka | Density | T/R |
|---|---|---|---|
| Old Growth Redwood | 480 lbf | 28 | 1.69 |
| Yellow-poplar | 540 lbf | 29.4 | 1.78 |
| Red Alder | 590 lbf | 28.7 | 1.66 |
| Butternut | 490 lbf | 26.6 | 1.88 |
About Sitka Spruce
Sitka spruce (Picea sitchensis) is a large tree that grows along the northwestern coast of North America from California to Alaska. It is also known as yellow, tideland, western, silver, and west coast spruce. Much Sitka spruce timber is grown in Alaska, but most logs are sawn into cants for export to Pacific Rim countries. Material for U.S. consumption is produced primarily in Washington and Oregon. The heartwood of Sitka spruce is a light pinkish brown. The sapwood is creamy white and shades gradually into the heartwood; the sapwood may be 7 to 15 cm (3 to 6 in.) wide or even wider in young trees. The wood has a comparatively fine, uniform texture, generally straight grain, and no distinct taste or odor. It is moderately lightweight, moderately low in bending and compressive strength, moderately stiff, moderately soft, and moderately low in resistance to shock. It has moderately low shrinkage. On the basis of weight, Sitka spruce rates high in strength properties and can be obtained in long, clear, straight- grained pieces. Sitka spruce is used principally for lumber, pulpwood, and cooperage. Boxes and crates account for a considerable amount of the remanufactured lumber. Other important uses are furniture, planing-mill products, sashes, doors, blinds, millwork, and boats. Sitka spruce has been by far the most important wood for aircraft construction. Other specialty uses are ladder rails and sounding boards for pianos.
Durability & sustainability
CITES status: not listed on any CITES Appendix — no international-trade restriction applies to Sitka Spruce.
Properties
| Specific gravity | 0.4 |
|---|---|
| Janka hardness (side) | 510 lbf |
| Density (air-dry, 12% MC) | 28 lb/ft³ (449 kg/m³) ovendry-weight basis: 25 lb/ft³ |
| Weight per board foot (air-dry) | 2.33 lb |
| Radial shrinkage (green→oven-dry) | 4.3% |
| Tangential shrinkage (green→oven-dry) | 7.5% |
| Volumetric shrinkage (green→oven-dry) | 11.5% |
| T/R ratio (stability indicator) | 1.7 |
Shrinkage is total green-to-oven-dry (Table 4-3); strength values are at 12% MC. Full bases and the derivation formulas are on the methodology page.
Data: USDA Forest Products Laboratory, Wood Handbook FPL-GTR-282 (2021), public domain.