Amdahl's Law Calculator
What is Amdahl's Law?

Amdahl’s Law is a formula which finds the maximum improvement gained by improving a particular part of a system. It is often used in parallel computing to predict the theoretical maximum speedup using multiple processors.

Amdahl's Law Formula

Slatency(s)=1(1p)+psS_{\text{latency}}(s)=\frac{1}{(1 - p) + \frac{p}{s}}


  • S_latency(s) is the theoretical speedup of the execution of the whole task.

  • s is the speedup of the part of the task that benefits from improved system resources.

  • p is the proportion of execution time that the part benefiting from improved resources originally occupied.

In the context of parallel computing s often refers to the number of processors in the system and p is the parallel portion of the program. In such a context, Amdahl’s law states that the speedup of a program using multiple processors in parallel computing is limited by the time needed for the sequential fraction of the program.

For example, if 95% of the program can be parallelized, the theoretical maximum speedup using parallel computing would be 20 times, no matter how many processors are used.