There's a calculator on the previous page for specific values, but here's a chart of Angular Field of View (Width, Height, Diagonal, in degrees) for many lens focal lengths ("Lens mm") on popular sensor sizes and common aspect ratios. One example of the chart use might be to compare the width of view on two cameras.
The calculation is NOT for fisheye lenses (their view will be wider), and it is not for macro distances. Field accuracy will be better at a distance of at least a few feet, because the lens focal length number changes with closer distance (better accuracy if magnification is < 0.1). The stated value of focal length applies to Infinity focus.
The top row marked WxH shows the sensor dimensions in mm, computed from the crop factor. The APS-C 1.61x and 1.53x crop numbers are realistically closer than the nominal 1.6x and 1.5x approximations we think of. Crop factor can be determined in the first calculator on previous page. Also 16:9 image size can be limited to be no wider than camera 3:2 or 4:3 sensors (or left at full size for camcorders). See HD movies on previous page.
There are many sizes of 4:3 sensors. Tiny sensors require very short focal length to achieve any usual field of view. Phones normally don't zoom, and we probably don't know focal length for compacts except at end extremes.
You can easily add another sensor into the chart (specify crop factor), which will replace the last sensor column (replaces the original default One Inch 2.73x crop initially in last column.) See Determine Crop Factor on previous page.
The last sensor is really just a place holder for any other sensor you want to add there instead. (Refresh the page to restore the original sensor).
FWIW, the size of our full Moon appears near 0.5 degrees (its size varies slightly in its elliptical orbit, 0.49 to 0.558 degrees).
For the same sensor, a 2x longer focal length shows a 2x larger subject view, cropped in a view dimension only half as wide. Or 4x is 4x size in a view 1/4 as wide, etc. But the numeric Angle of view number is not linear, meaning 2x is Not exactly true of widest angles (the numeric angle). But the resulting Field of View dimension is linear with focal length.