Black Oak wood movement, board-foot & weight calculator
- Janka
- 1,210lbf
- Density
- 42.6lb/ft³
- T/R ratio
- 2.5
- Spec. gravity
- 0.61
Black Oak is a North American hardwood. It has a Janka side hardness of 1,210 lbf, a specific gravity of 0.61, and an air-dry density near 43 lb/ft³ (682 kg/m³) (mechanical values at 12% moisture content). It shrinks 11.1% tangentially and 4.4% radially from green to oven-dry (T/R ratio 2.5), so a 12-inch flatsawn board moves about 0.27 in (≈ 9/32 in) across a 6-point moisture swing (about 6%→12% MC).
Compute Black Oak: movement, weight & board footage
Every number below is worked from Black Oak'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″ | 0.044″ (≈ 1/32 in) | 0.018″ (≈ 1/32 in) |
| 3″ | 0.067″ (≈ 1/16 in) | 0.026″ (≈ 1/32 in) |
| 4″ | 0.089″ (≈ 3/32 in) | 0.035″ (≈ 1/32 in) |
| 6″ | 0.133″ (≈ 1/8 in) | 0.053″ (≈ 1/16 in) |
| 8″ | 0.178″ (≈ 3/16 in) | 0.07″ (≈ 1/16 in) |
| 10″ | 0.222″ (≈ 7/32 in) | 0.088″ (≈ 3/32 in) |
| 12″ | 0.266″ (≈ 9/32 in) | 0.106″ (≈ 3/32 in) |
| 16″ | 0.355″ (≈ 11/32 in) | 0.141″ (≈ 5/32 in) |
Need a different width or moisture swing? Run the movement calculator preloaded with Black Oak. At a T/R ratio of 2.52, Black Oak is unstable — it moves far more tangentially than radially, the pattern behind cupped tabletops and opened joints — quartersawn stock and generous allowance for seasonal movement matter here.
Board footage & weight, standard sizes
| Nominal size × length | Board feet | Weight |
|---|---|---|
| 1×4 × 8′ | 2.67 bd ft | 9.5 lb |
| 1×6 × 8′ | 4 bd ft | 14.2 lb |
| 1×8 × 8′ | 5.33 bd ft | 18.9 lb |
| 1×10 × 8′ | 6.67 bd ft | 23.7 lb |
| 1×12 × 8′ | 8 bd ft | 28.4 lb |
| 2×4 × 8′ | 5.33 bd ft | 18.9 lb |
| 2×6 × 8′ | 8 bd ft | 28.4 lb |
| 2×8 × 8′ | 10.67 bd ft | 37.9 lb |
Different length or size? Run the board foot calculator or the weight calculator, both preloaded with Black Oak.
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 | 0.204″ (≈ 7/32 in) |
| Chicago, IL | May · 12.3% | Dec · 15.1% | 2.8 pts | 0.124″ (≈ 1/8 in) |
| Miami, FL | Apr · 12.2% | Sep · 14.4% | 2.2 pts | 0.098″ (≈ 3/32 in) |
| Boston, MA | Apr · 11.5% | Sep · 12.8% | 1.3 pts | 0.058″ (≈ 1/16 in) |
| Denver, CO | Jul · 8% | Dec · 10.5% | 2.5 pts | 0.111″ (≈ 1/8 in) |
| Seattle, WA | Jul · 12% | Dec · 16.9% | 4.9 pts | 0.218″ (≈ 7/32 in) |
Driven by Black Oak's tangential shrinkage of 11.1%. These are outdoor equilibrium-moisture figures, so they are an upper bound — a climate-controlled interior swings less. How this is calculated.
How Black Oak compares
Ranked against the 196 species in the Wood Handbook tables this site carries.
- Hardness: at 1,210 lbf, Black Oak is harder than 61% of the 157 species with a Janka figure.
- Weight: at 42.6 lb/ft³ it is heavier than 65% of the 170 species measured — an 8-foot 1×6 board weighs about 14.2 lb.
- Stability: its T/R ratio of 2.52 is more even than 3% of the 196 species here — as humidity changes, 97% of them hold their shape more evenly.
See Black Oak 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 Black Oak is unavailable or priced out.
- Teak is a common substitute for Black Oak : 17% softer, 10% lighter, and similarly stable in service.
- American Beech is a common substitute for Black Oak : nearly identical hardness, about the same weight, and more stable in service.
| Species | Janka | Density | T/R |
|---|---|---|---|
| Teak | 1,000 lbf | 38.4 | 2.32 |
| American Beech | 1,300 lbf | 44.7 | 2.16 |
About Black Oak
The Wood Handbook describes Black Oak as part of the Oak (Red Oak Group); the account below is of that group, which Black Oak belongs to.
Most red oak comes from the Eastern States. The principal species are northern red (Quercus rubra), scarlet (Q. coccinea), Shumard (Q. shumardii), pin (Q. palustris), Nuttall (Q. nuttallii), black (Q. velutina), southern red (Q. falcata), cherrybark (Q. falcata var. pagodaefolia), water (Q. nigra), laurel (Q. laurifolia), and willow (Q. phellos) oak. The sapwood is nearly white and roughly 2 to 5 cm (1 to 2 in.) wide. The heartwood is brown with a tinge of red. Sawn lumber of the red oak group cannot be separated by species on the basis of wood characteristics alone. Red oak lumber can be separated from white oak by the size and arrangement of pores in latewood and because it generally lacks tyloses in the pores. The open pores of red oak make this species group unsuitable for tight cooperage, unless the barrels are lined with sealer or plastic. Quartersawn lumber of the oaks is distinguished by its broad and conspicuous rays. Wood of the red oaks is heavy. Rapidly grown second- growth wood is generally harder and tougher than finer textured old-growth wood. The red oaks have fairly high shrinkage upon drying. The red oaks are primarily cut into lumber, railroad crossties, mine timbers, fence posts, veneer, pulpwood, and fuelwood. Ties, mine timbers, and fence posts require preservative treatment for satisfactory service. Red oak lumber is remanufactured into flooring, furniture, general millwork, boxes, pallets and crates, agricultural implements, caskets, wooden ware, and handles. It is also used in railroad cars and boats.
Durability & sustainability
CITES status: not listed on any CITES Appendix — no international-trade restriction applies to Black Oak.
Properties
| Specific gravity | 0.61 |
|---|---|
| Janka hardness (side) | 1,210 lbf |
| Density (air-dry, 12% MC) | 42.6 lb/ft³ (682 kg/m³) ovendry-weight basis: 38.1 lb/ft³ |
| Weight per board foot (air-dry) | 3.55 lb |
| Radial shrinkage (green→oven-dry) | 4.4% |
| Tangential shrinkage (green→oven-dry) | 11.1% |
| Volumetric shrinkage (green→oven-dry) | 15.1% |
| T/R ratio (stability indicator) | 2.5 |
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.