Sling tags will state capacities in vertical, choker, and basket configurations but that is just the starting point to determine the size sling to use. Often in the field we see riggers tighten the sling in such a way that it cinches the load and forms an angle (see photo).
Remember that a choker hitch has 75% of the capacity of a single leg only if the angle of choke is 120 degrees or greater. A choke angle less than 120 degrees can result in a capacity as low as 40% of the single leg. So, what does this mean exactly? Check out this video from The Crosby Group which does a great job demonstrating different choker hitch angles.