Glossary
What is WSJF (weighted shortest job first)?
WSJF (weighted shortest job first) is a sequencing rule that divides each job's cost of delay by its size or duration and does the highest ratio first, so the work that is most expensive to keep waiting per unit of effort goes ahead.
The idea comes from Don Reinertsen's work on product development flow, where it is a queueing rule: when jobs differ in both urgency and length, ordering them by cost of delay divided by duration minimises the total cost of waiting. The insight that survives every implementation is that a short job with a moderate cost of delay can rightly go ahead of a long one with a high cost of delay.
The WSJF formula, as SAFe calculates it
The formula is WSJF = cost of delay ÷ job size. In the Scaled Agile Framework, cost of delay = user and business value + time criticality + risk reduction or opportunity enablement, and job size is a relative estimate of the effort or duration. The job with the highest WSJF goes first.
The Scaled Agile Framework made WSJF its standard way to order a backlog, and replaced money with relative estimates. Cost of delay becomes the sum of three components: user and business value, time criticality, and risk reduction or opportunity enablement. Each is scored on a modified Fibonacci scale — 1, 2, 3, 5, 8, 13, 20 — relative to the other jobs, one column at a time, with the smallest in each column set to 1. Job size is scored the same way and stands in for duration.
An example. Job A scores 8 for value, 5 for time criticality and 2 for risk reduction: a cost of delay of 15. Its size is 5, so its WSJF is 3. Job B scores 5, 3 and 1 — a cost of delay of 9 — with a size of 2, giving 4.5. B goes first although A is worth more, because B holds A up for less time than A would hold up B.
WSJF vs RICE
Both divide value by effort; they differ in what counts as value. RICE asks how many people a change reaches and how much it moves them, which suits product bets. WSJF asks what waiting costs, which makes time explicit: a regulatory deadline scores high on time criticality with no user-facing value at all. The SAFe version is also purely relative — its numbers mean nothing outside the set of jobs scored together — where RICE at least tries to anchor reach to a real count.
When it fits, and when it does not
It fits a flow of comparable jobs competing for the same delivery capacity, re-scored regularly, where the question really is what to do next. It fits best when cost of delay can be stated in money per week, as Reinertsen intended; the relative version is easier to run and much easier to argue into whatever order the room already preferred.
It does not fit as a commitment decision. Job size is a proxy for duration, and the proxy breaks when a small job waits three weeks on another team or a large one can be done in parallel. Summing three relative scores is arithmetic on rankings. And the ratio says nothing about whether a job is understood well enough to size, or whether the team it lands on has room. WSJF sequences work that is ready; it cannot tell you which work is ready.
Related terms
- MoSCoW prioritisation
MoSCoW prioritisation is a technique that sorts requirements for a fixed timebox into four categories — Must have, Should have, Could have and Won't have this time — so that everyone agrees in advance what is dropped first if time runs short.
- Commitment exception
A commitment exception is a recorded justification required to commit to work that is not yet decision-ready, naming why it is early, what is still unknown, who accepts the risk, and what condition would change the decision.
- Delivery commitment
A delivery commitment is a recorded promise to deliver a stated outcome by a date, made by a named owner with the capacity the delivering teams agreed to give, and kept as a baseline that later results are compared against.
This definition comes from building DeliverySheet — it takes a vague work request to a clear delivery decision, so the shape, owner, capacity, dependencies and open questions are on the table before anyone commits people or a date.
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