I took a bunch of photos of the Sun using a Coronado sun telescope and manually stacked them using GIMP. The result was quite nice, I think you can see a large sun spot as well as a prominence (bottom of sun).
So, how big is this prominence? I measure that it rises ~30,648.94 miles above the sun and has an apparent width of around ~202,282.98 miles!
That prominence is 3.87 Earths in height and 25.56 Earths long!!!
Diameter of sun image is 987px.
Avg. diameter of sun: 864300 miles.
So, 864300 miles / 987px= 875.6838905775076 miles/px
Maximum height of the prominence is 35px
Therefore, 35px * 875.6838905775076 miles/px = 30648.93617021277 Miles
Call is ~30,648.94 Miles