# Is the “wing area” of a biplane the projected area or the total area?

When you specify the wing area of a biplane, do you specify the planform area (the projected area) or do you specify the effective area of both the wings?

• I could have sworn we had this exact question, or a very similar one about interference and effective wing area, but I can't find it. – AEhere supports Monica Oct 25 '19 at 7:59

It's a mixture of both: You add the projected area of both wings, measured separately, without overlap.

The effective (wetted) area is used for friction drag calculations only.