After wood is cut it is left to dry. The size of the wood before it was left to dry is called the nominal size (1x4, 2x4, etc) while the size of the wood after it has dried is called the true size.

| Nominal Size | True Size |

| ------------ | ------------- |

| 1x4 | 3/4"x3 1/2" |

| 2x4 | 1 1/2"x3 1/2" |

| 1x6 | 3/4"x5 1/2" |

| | |