First of all, you need this simple formula:
dome radius = strut length/strut factor

which is the same as:
strut length = dome radius * strut factor

Now all you need are the strut factors!

Strut	Strut factor	Dome	3/8th	5/8	Sphere	Image
1V Dome
A	1.05146	25			30
5-way connectors		6			12
4-way connectors		5			0
2V Dome
A	.61803	35			60
B	.54653	30			60
4-way connectors		10			0
5-way connectors		6			12
6-way connectors		10			30
3V Dome
A	.34862		30	30	60
B	.40355		40	55	90
C	.41241		50	80	120
4-way connectors			15	15	0
5-way connectors			6	6	12
6-way connectors			25	40	80
4V Dome
A	.25318	30			60
B	.29524	30			60
C	.29453	60			120
D	.31287	70			120
E	.32492	30			60
F	.29859	30			60
4-way connectors		20			0
5-way connectors		6			12
6-way connectors		65			150
5V Dome
A	.19814743	30			60
B	.23179025	30			60
C	.22568578	60			120
D	.24724291	60			120
E	.25516701	70			120
F	.24508578	90			120
G	.26159810	40			60
H	.23159760	30			60
I	.24534642	20			30
4-way connectors		??			0
5-way connectors		6			12
6-way connectors		??			??
6V Dome
A	.1625672	30			60
B	.1904769	30			60
C	.1819083	60			120
D	.2028197	90			180
E	.1873834	30			60
F	.1980126	60			120
G	.2059077	130			240
H	.2153537	65			120
I	.2166282	60			120
4-way connectors		??			0
5-way connectors		6			12
6-way connectors		??			??

Equations for Calculator

• Circumference = π 2r
• Area of a circle = π r²
• Surface area of sphere = 4 π r²
• volume of a sphere = (4/3) π r³

Angles

The bending angles are as follows:
1v dome: bend 32º on each end
2v dome: bend A’s 18º, and B’s 16º on each end
3v dome: bend A’s 10º, B’s and C’s 12º on each end
4v dome: bend all struts 7º-9º on each end
5v dome: bend all struts 6º-7º on each end
6v dome: bend all struts 5º-6º on each end