According to the "Welding Shop Foreman's Manual", published years ago by Lincoln Electric, for estimating purposes (cost estimating, for example) it can be safely assumed that the average efficiency of welding rods is 60%, i.e., 1 kilogram of welding rods will give 600 grams of deposited metal. The other 400 consist of slag, combustion gases and the butts that the welder throws away.
Giovanni S. Crisi
Sao Paulo - Brazil