Calc stacking is a term used to refer to the practice of basing calculations on numbers determined from previous calculations. For example, if X was calced to be mach 5 from a bullet timing feat, and Y speedblitzed X, a calc stacker would use mach 5 as X's speed to calc the speed of Y.

In most cases, calc stacking is considered to be a very flawed method, often coming up with insanely inflated speeds, such as Mach 120 Lucci, Mach 200 Raikage, and Mach 500 Starrk. This is due to a number of factors, including the fact that characters' speeds are not always consistent compared to real - world entities such as bullets and lasers.

Calculations based on calc stacking should be viewed with extreme skepticism at best, and outright dismissed most of the time.