camera basics - Why does this article say that a 1.5× crop factor sensor is 43% smaller than a 35mm film cell?

From http://www.digitalbirdphotography.com/2.3.html

In the case of full-frame sensors, the pixels are spread out over a relatively large sensor: roughly 36mm by 24mm. This just happens to be the size of a 35mm film cell (remember film cameras?), and has come to be known as full-frame (despite the fact that there are even larger sensors, known as medium format sensors).

As of this writing, most consumer-grade digital cameras are not full-frame: they are cropped, meaning that they are smaller than a full-frame sensor.

For cameras with a 1.5x crop factor, the sensor is 43% smaller in both width and height than a 35mm film cell, resulting in a sensor with 66% less area than a full-frame sensor—a rather substantial loss in sensor size. This is because the crop factor is applied to both the width and the height separately.

In the example for a camera with a 1.5x crop factor, is its width (or height) 1/1.5=0.67 of the width (or height) of a full frame sensor? Why "the sensor is 43% smaller in both width and height than a 35mm film cell"?

Is its area (1/1.5)^2 = 0.44 of the area of a full frame sensor? Why "resulting in a sensor with 66% less area than a full-frame sensor—a rather substantial loss in sensor size"?

Answer

The article you've quoted and linked to just seems to have some bad maths.

When they're subtracting the percentages from 100, they seem to have forgotten to 'carry the one', so to speak. They've subtracted 66.66% from 100% and got 43%, and then 44% from 100% and come up with 66%.

It should say the sensor's edges are 33% shorter (not 43%), with a total area 55% less than the full-frame sensor (not 66% less).