How to use the center of gravity calculator
When a heavy skid, vessel or machine is rigged without knowing where its center of gravity sits, the load tilts the moment it leaves the ground and one sling picks up far more than its share. Setting the item level on two supports and reading each reaction with load cells or scales gives you the CG through simple moment equilibrium.
The formula is distance from A = reaction at B × span ÷ (reaction at A + reaction at B). Equal readings put the CG exactly at mid-span; a heavier reading pulls the CG toward that support. Because total weight is just the sum of the two readings, you also confirm the lift weight without a separate weighing.
Weigh the load in a level position. Tilted cribbing, soft ground or a support that is not fully seated distorts the readings and shifts the calculated CG. The math covers one axis at a time, so rotate the load 90 degrees and repeat if you also need the transverse center of gravity.
Treat the result as the starting point of a rigging plan, not the finished plan. Sling angles, hook position and the crane load chart all have to be checked as well, and the finished lift plan should be reviewed by a qualified rigger or lifting engineer before the pick.
Frequently asked questions
Yes. Set the load level on two supports and weigh each reaction. Moment equilibrium fixes the CG: distance from A equals reaction at B times the span divided by total weight.
This calculation covers one axis only. Rotate the load 90 degrees, weigh both supports again, and apply the same formula to get the transverse center of gravity.
No. Tilted cribbing or uneven ground distorts the reactions. Confirm the rigging plan against the crane load chart and have a qualified rigging engineer review it.