The harvest cluster weight method is based on the number of producing vines per acre, the average number of clusters per vine, and the average cluster weight at harvest from previous years to predict the yield in tons per acre for the current season.
The lag phase cluster weight method is based on the number of producing vines per acre, the average number of clusters per vine, and the average cluster weight at the lag phase state of the grape with the use of a multiplier to predict the yield in tons per acre for the current season. Cluster weights will double from lag phase to harvest time. The multiplier in this calculator is set at 2 but this number can vary depending on various factors.
Sampling method and amounts of samples taken to obtain averages is beyond the scope of this calculator. Accuracy counts!