The size of PVC to use for furniture will depend on the specific design and intended use of the furniture. PVC pipes used in furniture projects are typically available in a variety of diameters, ranging from 1/2 inch to 2 inches or more.

When choosing the size of PVC to use for furniture, it is important to consider the intended weight capacity and load-bearing requirements of the furniture. For example, if you are building a table or a bookshelf, you may want to use thicker PVC pipes to support the weight of the tabletop or the books.

As a general rule, 1 inch or 1.25 inch diameter PVC pipes are commonly used for the legs and support structures of most furniture projects. Thicker pipes may be used for weight-bearing elements, such as the frame of a bed or the base of a heavy chair.

It is also important to consider the thickness of the PVC pipe walls. Thicker walls can provide added strength and durability, but may also be heavier and more difficult to work with.

Ultimately, the size of PVC to use for furniture will depend on the specific needs of the project. Careful planning and consideration of the weight capacity and load-bearing requirements of the furniture will help ensure that the appropriate size and thickness of PVC is selected.