Setup and hold timing calculator

Practice simplified single-path timing arithmetic. All values are in nanoseconds. Positive skew means the capture clock arrives later than the launch clock.

Setup check

Available setup time = period + positive capture skew − setup time − uncertainty. Data arrival = clock-to-Q maximum + maximum combinational delay.

Clock periodClock-to-Q maxCombinational maxSetup timeClock skewClock uncertainty

Hold check

Data arrival = clock-to-Q minimum + minimum combinational delay. Required hold = hold time + positive capture skew + uncertainty. Hold slack = arrival − required hold.

Clock-to-Q minCombinational minHold timeClock skewClock uncertainty

Interpretation and common mistakes

Slack of zero or above is PASS in this simplified model; negative slack is a VIOLATION. A later capture clock helps the stated setup equation but hurts the stated hold equation. Sign conventions differ by report and tool, so inspect the constraints before comparing numbers.

Do not use this page as a signoff result. Confirm min/max libraries, corners, clock definitions, exceptions, asynchronous crossings and generated-clock behavior in an STA flow.

Read Setup Time vs Hold Time · Read Static Timing Analysis · Semiconductor & VLSI hub