When it comes to selecting the right size of nails for baseboards, there are a few things to consider. The ideal length of the nail should be between 1.5 and 2 inches, and the gauge indicates the diameter or thickness of the nail. Most contractors recommend using nails with a gauge of 15 or 16 for fastening baseboards, as their size assures good holding power for baseboards to stay in place. Here are some additional tips to help you choose the right size of nails for your baseboards:

• Finish nailer vs. brad nailer: For connecting the baseboards, you will need to choose between a finish nailer and a brad nailer. A finish nailer is recommended for baseboards, and it will come down to choosing between a 15 or 16 gauge nailer. A 15 gauge finish nailer is ideal for baseboards and other trim pieces that are about 3/4 of an inch thick, while a 16 gauge finish nailer is suitable for thinner baseboards.

• Brad nails: Brad nails are best used for base caps and shoe molding. If you are using a brad nailer, it is recommended to use 15-gauge 2-inch nails for baseboards. However, you may need to analyze your setup for what length is appropriate.

• Nail length: The length of the nail will depend on the thickness of the baseboard. For attaching baseboards, 15 or 16 gauge nails up to 2.5 inches long are ideal for thicker baseboards and studs, while 18 gauge nails are best for thin trims that can split easily.

In summary, the recommended size of nails for baseboards is between 1.5 and 2 inches in length, with a gauge of 15 or 16. A finish nailer is recommended for baseboards, while a brad nailer is best for base caps and shoe molding. The length of the nail will depend on the thickness of the baseboard, with 15 or 16 gauge nails up to 2.5 inches long being ideal for thicker baseboards and studs, and 18 gauge nails being best for thin trims.