Setup Slack Calculator

About this calculator

This calculator computes the setup timing slack of a synchronous digital path between two flip-flops, one of the two checks (alongside hold slack) that make up static timing analysis (STA). The formula is Clock Period + Clock Skew − Data Path Delay − Setup Time: positive slack means the data arrives with margin to spare before the next clock edge; negative slack means the path is too slow and the circuit will fail at that clock frequency.

Digital and FPGA/ASIC designers use setup slack analysis to find the critical path in a chip and to determine the maximum safe clock frequency, which is simply the inverse of the minimum clock period that keeps slack non-negative across every path.