# How is the wing area of an airplane determined?

Picture source is from here.

Here are wing areas of several airplanes. As we can see the Spitfire, B747-400, and Mirage 2000, their wing area are not rectangular. The line drawn from left side to the right side of the fuselage are not parallel to their fuselage's cross-section, or they are not perpendicular to the fuselage. The connecting line in the drawing of the Spitfire is curving (bulge) on the trailing edge side, while the B747-400 and the Mirage 2000 have pointing shape on the leading edge side. As we know that the wing area (hence also affects the aspect ratio) is very critical to an airplane to make it fly as wing area is included in the lift formula, so, what I want to ask here are:

1. Is that depiction correct? If it is correct, then my further question is, why does not all the airplane body (except the horizontal stabilizer) considered as wing area?
2. If it is not true, then how should I determine the wing area?

So far, what I found in many explanations is that the wing is the area from root to the wing tip times two, both sides calculated then times two as there area two wings, left and right. With the information in that link then all calculation will be changed: both wing area and the aspect ratio will be changed, calculation will be affected.

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Edit/Added: There is a good article here explains about wing area. Based on that article, neither the first nor the second question is true as there is no solid method about how to calculate that wing area. There are three definition about wing area: Trapezoidal, Wimpress (which is used by Boeing), and Airbus. But what is confirmed from that article is that the fuselage between the wing root in included as wing area regardless of whether it defined according to Trapezoidal, Wimpress, or Airbus' definition.

Typically, the reference wing area Sref, span b, and aspect ratio AR are based on somewhat simplified wing forms. The reference wing extends to the aircraft centerline.

In the case of the aircraft shown, the reference wing probably matches what you've depicted -- with the exception of the 747. For the 747, the reference wing likely excludes the trailing edge extension and any winglets.

Although these quantities are important for the aerodynamics and performance of the aircraft, they can also be somewhat ignored.

Imagine you have a wing with a very odd shape that is hard to deal with. You could calculate a simplified reference wing with roughly equivalent Sref, b, AR. As long as you always calculate the reference quantities the same way for odd shaped wings like this one, you'll be fine.

• What is the definition of, or what do you mean with, Sref? Wing span and Aspect ratio of course no problem. Oct 2, 2023 at 21:07
• Sref is the wing reference area. I don't really know why we use S for it, but that is convention in aerospace engineering. Oct 2, 2023 at 22:56
• S for surface? . Oct 3, 2023 at 2:52
• @AnonymousPhysicist I don't think so. The surface area is a little more than 2x the reference area. Really it is no more a mystery than why we use b for wingspan. Oct 3, 2023 at 4:34
• @RobMcDonald AFAIK S stands for "(projected) Surface area" Oct 3, 2023 at 7:06