For 3/4 inch material, use 1 1/4 inch pocket screws.
For 1/2 inch plywood, you should use 1 inch pocket hole screws.
For 3/4 inch wood, you should use 1 1/4 inch pocket hole screws.
Pocket holes typically require 1 1/4-inch coarse-thread screws for softwoods and 2 1/2-inch coarse-thread screws for hardwoods.
For most woodworking projects, 1 1/4 inch or 1 1/2 inch pocket hole screws are commonly used. The size of the screw you should use depends on the thickness of the wood you are working with.
For joining 1x4 boards together, it is recommended to use 1-1/4 inch pocket hole screws.
For most projects, using 1 1/4 inch or 1 1/2 inch pocket hole screws should be sufficient. The length of the screw should be slightly shorter than the combined thickness of the two pieces of wood being joined.
The Kreg screw chart recommends using 1 1/4-inch screws for 1/2-inch thick material, 1 1/2-inch screws for 3/4-inch thick material, and 2 1/2-inch screws for 1 1/2-inch thick material in woodworking projects.
For attaching cabinet door securely, use 1-inch wood screws for hinges and 1/2-inch screws for handles. Make sure to use screws that are appropriate for the material of the cabinet door.
For installing shelf brackets, it is recommended to use wood screws that are at least 1 inch in length and have a diameter of 1/4 inch. Make sure the screws are appropriate for the material of the wall or surface you are attaching the brackets to.
For a typical 2x4 project, you should use 3-inch screws.
When installing a subfloor, it is recommended to use 2-inch screws for plywood subfloors and 1 1/4-inch screws for OSB subfloors.
For 1/2 inch plywood, it is recommended to use 6 or 8 screws.