# Little's Law ## The Idea in Brief More work in progress means longer wait times. That's the brutal simplicity of Little's Law: cycle time equals WIP divided by throughput. If you want things to move faster, adding more work makes it worse. The only levers are finishing more or starting less. --- ## Key Concepts ### The Formula **L = λW** — the average number of items in a system equals the throughput rate times the average time each item spends there. Rearrange it and you get the insight that matters: **W = L/λ**. Wait time is WIP divided by throughput. This holds under remarkably general conditions. It doesn't matter how work arrives, how it's prioritised, or how variable the processing times are. As long as the system is stable (stuff going in roughly equals stuff coming out), Little's Law applies. ### Why WIP Kills Flow If your throughput is fixed—and in most organisations it effectively is—then every extra item in the queue lengthens the wait for everything else. Start a new initiative before finishing the last three, and all four take longer. This is why "just start it" is so destructive. Each new project feels costless, but it taxes every other project in the system. ### The Management Trade-off You can optimise two of the three variables (WIP, throughput, lead time) but the third is determined by Little's Law. Most organisations obsess over throughput while letting WIP run wild—which is exactly backwards. Reducing WIP is often the fastest path to shorter lead times. --- ## Implications **In operations:** Before asking "how do we speed up delivery?", ask "how much WIP do we have?" The answer is usually "too much." Impose WIP limits. Finish things before starting new ones. **In product development:** Roadmaps packed with initiatives feel productive but guarantee slow delivery. Fewer concurrent projects means each one finishes faster—even if you don't add any capacity. **In your own work:** That feeling of drowning? Count your open loops. Every half-finished task, every "I'll get to it", every tab in your browser—they're all WIP. Close some. The rest will move faster. --- ## Sources - [[The Haystack Syndrome]] — Goldratt's application of flow principles to manufacturing; WIP discipline as competitive advantage - [[The Phoenix Project]] — IT operations as factory floor; WIP limits transform delivery speed --- ## See in Notes - [Capacity and Flow](https://www.anishpatel.co/capacity-and-flow/) — Little's Law explains why adding WIP slows everything: each extra item lengthens the wait for everything else - [Expensive Yes](https://www.anishpatel.co/expensive-yes/) — The hidden queue: before saying yes, ask what it does to lead time