Lateral strength is largely a function of a nail’s diameter and the density of the type of wood into which the nail is driven. For example, 10d and 12d nails have the same diameter and the same lateral strength in each type of wood. Common nails are stronger than box nails because of their greater diameter (below).

Figure: Lateral Strength of Common vs. Box Nails
Side member and main member
Penny Wt. 8d 10d 12d 16d 20d
Nail Type Common Box Common Box Common Box Common Box Common Box
Diameter (in.) 0.131 0.113 0.148 0.128 0.148 0.128 0.162 0.135 0.192 0.148
Side Member Thickness (in.) 0-3/4 0-3/4 0-3/4 1 1/2 1 1/2
Lateral Rating (lb.)
SPF 70 57 83 68 83 68 120 88 144 100
D-F-L 90 72 105 87 105 87 141 103 170 118
Hem-Fir 73 58 85 70 85 70 122 89 147 102
SYP 104 79 121 101 121 101 154 113 185 128

Nails are rated for “lateral capacity,” which is greatly affected by the nail’s diameter. Since box nails are skinnier than commons, they have lower strength values. The values shown vary with the type of framing lumber used, and they assume the nail will penetrate the main member (illustration at top) at least 12 diameters.


When substituting box for common nails, calculate the nail size needed using the conversion ratios shown below.

Figure: Conversion Ratio for Common to Box Nails
Penny Wt. 8d 10d 12d 16d 20d
Ratio 1.23 1.22 1.22 1.36 1.44

S-P-F lumber assumed.

Do not substitute a common nail that’s specified on the plans for an equal number of box nails. Instead, multiply the specified number of common nails by the conversion ratio shown in the chart and round up to find the equivalent number of box nails.