The formula

WSJF = Cost of Delay ÷ Job Size, where Cost of Delay is the sum of three components: user/business value, time criticality, and risk reduction or opportunity enablement. It comes from the Scaled Agile Framework (SAFe) and answers a specific question - among several jobs competing for the same team's time, which one should go first to minimize the total cost of delay across all of them.

Why divide by job size at all

Two items can have identical Cost of Delay and still deserve different priority if one takes a week and the other takes a quarter - WSJF explicitly favors the shorter job when value is equal, which is the "weighted shortest job first" the name describes. This is the same intuition behind doing the quick email before the long phone call when both are equally important.

Using a shared relative scale

All four inputs need to be on the same relative scale - typically the same Fibonacci-style values used for story points - so the numbers mean the same thing across every item being compared. Mixing scales (job size in story points, value in a 1-10 gut-feel scale) breaks the ratio in ways that aren't obvious from the output score alone.

What WSJF doesn't settle

Like every prioritization scoring method, WSJF makes the relative comparison explicit - it doesn't make the underlying value or risk estimates objectively correct. A team with badly calibrated inputs gets a precise-looking wrong answer, not a right one.