Abstract In cold forming operations, the two primary considerations in determining process feasibility are load and energy required to form the part. These two factors determine the press size and therefore the maximum production rate. Close estimations of these values during the process planning stage allow for accurate machine sizing and lead to higher efficiency. However, methods for estimating forming loads and energies of flashless closed-die upsets are not well researched. The objective of this study was to develop guidelines for this purpose. Experiments were conducted to measure the load during many flashless closed-die upsets. These results were compared to predictions made using a mathematical model (modified slab method) and an FEM analysis (DEFORM 2D) to gauge the ability to accurately predict forging loads. Additionally, FEM was used to study the sensitivity of the forging load to friction conditions, part size, and average material strain. The results indicate that the modified slab method predictions are quite accurate in some cases but overestimate the load by as much as 35% in others. The DEFORM 2D load predictions are more consistent but generally underestimate the load by 5–20%.