Mangoes, We still have to consider the SWL in hardware. It's 5-7 to 1 depending on the manufacturer. As the loads and hardware increase, so does the cable diameter.
1/4" EHS cable is good for up to 20" diameter limbs. (1,200 lbs. SWL)
5/16" EHS cable is good for up to 24" limbs. (2,200 lbs. SWL)
After this the standard jumps to 7/16" EHS cable, which IMO is overkill.
3/8" EHS cable is good for up to 28" limbs (IMO). (3,300 lbs. SWL)
> 28" 7/16' EHS is reco'd. (3,700 lbs. SWL)
EHS= Extra High Strength, 7 strand or 1 X 7.
The largest I have worked with is 3/8" EHS.