Overview

• What you’ll learn: The four flow metrics (WIP, Throughput, Cycle Time, Work Item Age), how to measure them, what they reveal about your team’s performance, and how to use them for improvement.
• Prerequisites: Lesson 33 — Kanban Definition and Principles.
• Estimated reading time: 16 minutes

Introduction

You cannot improve what you cannot measure. This ancient management truism is especially relevant for Scrum teams adopting Kanban. The Kanban Guide defines four key flow metrics that, together, paint a comprehensive picture of how work moves through your system.

These are not vanity metrics. They are actionable signals that tell you where your process is working and where it is breaking down. Let’s examine each one.

1. Work in Progress (WIP)

Definition: The number of work items started but not finished at a given point in time.

WIP is the most fundamental metric because it directly affects all other flow metrics. More WIP means longer cycle times, older work items, and — counterintuitively — lower throughput. This is not opinion; it is mathematics (see Little’s Law in Lesson 35).

How to measure: count every item that is in a “started” column on your board but not yet in a “done” column. If you have 12 items in progress and only 5 developers, something is wrong. Either items are blocked, or people are multitasking — both are flow killers.

2. Throughput

Definition: The number of work items finished per unit of time (usually per Sprint or per week).

Throughput tells you the delivery rate. If your team finishes 8 items per Sprint consistently, your throughput is 8. If it fluctuates wildly between 3 and 15, you have a predictability problem.

Throughput is valuable for forecasting. Instead of guessing when a project will be done, you can use throughput data and Monte Carlo simulations to give probabilistic forecasts: “There is an 85% chance we will finish the remaining 24 items within 3 Sprints.”

3. Cycle Time

Definition: The elapsed time from when a work item is started to when it is finished.

Cycle Time = how long a single item takes from start to finish. A team with low WIP and high throughput will typically have short cycle times. A team with high WIP and lots of blockers will have long cycle times.

Track cycle time by item type (bug, feature, spike) and size to get meaningful insights. A 2-day cycle time for bugs and a 14-day cycle time for features is normal. A 45-day cycle time for a “small” bug is a screaming red flag.

4. Work Item Age

Definition: The elapsed time since a work item was started — measured while the item is still in progress.

Think of Work Item Age as “cycle time for items that aren’t done yet.” If your average cycle time is 5 days and you have an item that has been in progress for 12 days, that item is aging badly. It is a signal that something is wrong — a blocker, a dependency, scope creep, or someone forgot about it.

Work Item Age is a leading indicator: it warns you of problems before they show up in cycle time data. Monitor it daily in Daily Scrum.

Using Metrics Together

No single metric tells the whole story. Use them together:

• High WIP + Low Throughput = team is overloaded. Reduce WIP immediately.
• Low WIP + High Throughput + Short Cycle Time = healthy flow. Protect this state.
• Increasing Work Item Age = items are getting stuck. Investigate blockers in Daily Scrum.
• Fluctuating Throughput = unpredictable delivery. Look for special causes (holidays, dependency delays, scope changes).

Key Takeaways

• Four flow metrics: WIP, Throughput, Cycle Time, Work Item Age.
• WIP is the most fundamental — it affects all other metrics.
• Throughput enables probabilistic forecasting.
• Work Item Age is a leading indicator of stuck work.
• Use all four together for a complete picture.