The Janka hardness ratings are useful in determining how well a wood species will withstand dents, dings, and wear—as well as indirectly predicting the difficulty in nailing, screwing, sanding, or sawing.
The numbers listed in the table below is the amount of pounds-force (lbf), kilogram-force (kgf), or newtons (N) required to embed a .444 inch (11.28 mm) diameter steel ball into the wood to half the ball’s diameter. That particular diameter was chosen to produce a circle with an area of 100 square millimeters. The numbers are given for wood that has been dried to a 12% moisture content, unless otherwise noted.
The Janka hardness ratings are stated in different ways in different countries, leading to confusion as the name of the actual unit used is often not given. While in the United States the measurement is in pounds-force (lbf), in Sweden, for example, it is in kilograms-force (kgf), and in Australia it is in either newtons (N) or kilonewtons (kN). Sometimes the Janka hardness ratings are used as units themselves, e.g., “360 janka”.
The relationship between the different units are:
| Unit | Conversion (Approx) | Example |
|---|---|---|
| lbf | kgf × 2.2046 | 1221 lbf = 554 kgf × 2.2046 |
| lbf | N × 0.22481 | 1221 lbf = 5,430 N × 0.22481 |
| kgf | lbf × 0.45359 | 553 kgf = 1220 lbf × 0.45359 |
| kgf | N × 0.10197 | 554 kgf = 5430 N × 0.10197 |
| N | lbf × 4.448222 | 5,427 N = 1220 lbf × 4.448222 |
| N | kgf × 9.80665 | 5433 N = 554 kgf × 9.80665 |
The conversion factors are approximations that are good enough for day-to-day use—you may have noticed the rounding errors in the examples. In the table below, where the kgf value is unknown it is calculated using the lbf value or if the lbf value is unknown, it is calculated using the N value.
| Name(S) | lbf | kgf | N | Notes |
|---|---|---|---|---|
| Hard Maple (Acer saccharum) Sugar Maple Rock Maple |
1,450 | 658 | 6,450 | |
| White Oak (Quercus alba) | 1,350 | 612 | 5,990 | |
| Red Oak (Quercus rubra) | 1,220 | 554 | 5,430 | |
| Black Walnut (Juglans nigra) | 1,010 | 458 | 4,490 | |
| Bigleaf Maple (Acer macrophyllum) | 850 | 386 | 3,780 | A soft maple. |
| American Elm (Ulmus americana) Soft Elm Water Elm |
830 | 376 | 3,690 | |
| Douglas-Fir (Pseudotsuga menziesii) | 620 | 281 | 2,760 | |
| Poplar (Liriodendron tulipifera) Tulip Poplar Yellow Poplar |
540 | 245 | 2,400 | |
| Ponderosa Pine (Pinus ponderosa) | 460 | 209 | 2,050 | |
| Redwood (Sequoia sempervirens) Sequoia Coast Redwood California Redwood Vavona (burl) |
450 | 204 | 2,000 | |
| Basswood (Tilia americana) American Basswood Lime Linden |
410 | 186 | 1,824 | |
| Balsa (Ochroma pyramidale) | 90 | 41 | 390 |
Wood Groups
White Oak
| Name(S) | lbf | kgf | N | Notes |
|---|---|---|---|---|
Red Oak
| Name(S) | lbf | kgf | N | Notes |
|---|---|---|---|---|
Soft Pine
| Name(S) | lbf | kgf | N | Notes |
|---|---|---|---|---|
| Eastern White Pine (Pinus strobus) | 380 | 1,690 | Finest texture (i.e., smallest diameter tracheids) and the smallest resin canals. | |
| Limber Pine (Pinus flexilis) | 430 | 1,910 | Not commonly used. | |
| Sugar Pine (Pinus lambertiana) | 380 | 1,690 | Coarsest texture and the largest resin canals. | |
| Western White Pine (Pinus monticola) Idaho White Pine |
420 | 1,870 |
Hard Pine
Southern Yellow Pine
Southern Yellow Pine is mentioned in a lot of YouTube videos, usually from people in the eastern part of the country. It doesn’t seem to be as commonly available in the western part.
| Name(S) | lbf | kgf | N | Notes |
|---|---|---|---|---|
| Major Species | ||||
| Loblolly Pine (Pinus taeda) | 690 | 3,070 | ||
| Longleaf Pine (Pinus palustris) | 870 | 4,120 | ||
| Shortleaf Pine (Pinus echinata) | 690 | 3,070 | ||
| Slash Pine (Pinus elliotti) | 760 | 3,380 | ||
| Minor Species | ||||
| Pitch Pine (Pinus rigida) | 620 | 2,760 | ||
| Pond Pine (Pinus serotina) | 740 | 3,290 | ||
| Sand Pine (Pinus clausa) | 730 | 3,250 | ||
| Spruce Pine (Pinus glabra) | 700 | 3,110 | ||
| Table Mountain Pine (Pinus pungens) | 730 | 3,250 | ||
| Virginia Pine (Pinus virginiana) | 740 | 3,290 | ||
| Miscellaneous | ||||
| Caribbean Pine (Pinus caribaea) | 1,110 | 4,920 | Commonly grown on plantations. Nearly identical to the four major species of Southern Yellow Pine. | |
Western Yellow Pine
| Name(S) | lbf | kgf | N | Notes |
|---|---|---|---|---|
| Major Species | ||||
| Lodgepole Pine (Pinus contorta) | 480 | 2,140 | ||
| Ponderosa Pine (Pinus ponderosa) | 460 | 2,050 | ||
| Minor Species | ||||
| Jeffrey Pine (Pinus jeffreyi) | 500 | 2,220 | Anatomically indistinguishable from, and also sold as, Ponderosa Pine. | |
| Miscellaneous | ||||
| Jack Pine (Pinus banksiana) | 570 | 2,540 | ||
| Radiata Pine (Pinus radiata) | 710 | 3,150 | ||
Red Pine
| Name(S) | lbf | kgf | N | Notes |
|---|---|---|---|---|
| Red Pine (Pinus resinosa) | 560 | 2,490 | Only American species of Red Pine. Closely related to Austrian Pine (Pinus nigra) and Scots Pine (Pinus sylvestris) in Europe. |
Pinyon Pine
| Name(S) | lbf | kgf | N | Notes |
|---|---|---|---|---|
| Pinyon Pine (Pinus edulis) | 860 | 3,830 | Seldom used for lumber. |