Ask WWGOA: Joiner Biscuit Sizes


I ordered a Porter Cable biscuit jointer and was wondering what size biscuits to order. How do you determine what size biscuit is used for a particular job. I have read about PC’s FF size but am still confused. Your advice is appreciated.

Submitted by HHolmes


The three common biscuit sizes are 0, 10, and 20. You can find these almost anywhere, from home centers to specialty stores. While biscuits are a great joinery solution, they do have a few limitations. One is the length of the slot required to use a biscuit. Even the smallest biscuit, the 0, requires a slot that’s too long to use on the end grain of a 1-1/2″ wide face frame rail. This problem is solved by the FF biscuits. They’re round, instead of football shaped, and require a different cutter. Biscuit joiners typically use a 5″ diameter cutting blade. Some machines, like the Porter Cable 557, allow you to swap to a smaller diameter blade and use the FF biscuits. If your machine doesn’t allow the change to a smaller blade, you can’t use the FF biscuits.

When choosing what biscuit to use, go with the largest biscuit that will work for your application.


Do you have a question for WWGOA? Ask us on Facebook or email Note: questions may be edited for clarity and relevance.
  • (will not be published)

7 Responses to “Ask WWGOA: Joiner Biscuit Sizes”

  1. Jeff

    A standard biscuit blade is not 5″; it is 4″ x 5/32″ which is an approximation of the metric size 100 mm x 4 mm. The arbor is 22 mm or 7/8″.

    • Customer Service

      Hi Zach. It would not be recommended because there wouldn’t be much biscuit protruding from the slot after you slipped it into the first side, but if the biscuit protrudes at all (which I think it should) it might provide some aid in aligning the joint, so perhaps some slight value.

  2. Jim Young

    I recently picked up a used biscuit joiner. When I make a practice cut the physical width of the opening measures .230″. What size biscuit do I need for this opening?

    • Customer Service


      Most biscuit joiners allow for an adjustment to be made to the depth of cut in order to allow the use of multiple sized biscuits; #0, #10, and #20. All of these biscuits are the same thickness. If yours supports only one size I’d suggest consulting with the manufacturer or the manual to know the biscuit size. #20 is the most commonly used size.

      Woodworkers Guild of America