Delivery Pipeline Flow Calculator
How long work takes to get through a delivery pipeline from how much is in progress and how fast it finishes — Little's law — and how much work in progress a target cycle time allows.
Little's law is three numbers and a division: items in progress equals throughput times cycle time.
How the delivery pipeline flow calculator works
Little's law is three numbers and a division: items in progress equals throughput times cycle time. Twenty-four open pull requests finishing at eight a week means each one takes three weeks, whatever anyone intended. The only ways to cut cycle time are to finish more or start less, and starting less is the one that is free.
It holds for any stable queue — tickets, deploys, code review — which is why it is the first thing to compute when a pipeline feels slow.
Formula: WIP = throughput × cycle time ⇒ cycle time = WIP / throughput
Worked examples
| Inputs | Average cycle time (days) | Note |
|---|---|---|
| 24 in progress, 8 a week | 21 | three weeks each |
| WIP capped | 7 | one week |
| A faster team | 7 | also one week |
FAQFrequently asked questions
What is Little's law?
For any stable system, the average number of items inside equals the arrival rate times the average time each spends. It needs no assumptions about the distribution — it is arithmetic, not statistics.
Why does limiting WIP speed things up?
Because cycle time is WIP over throughput. With throughput fixed by the team, the only lever that moves cycle time is how much is in flight.
Does it apply to software?
To any queue: pull requests awaiting review, tickets in progress, deploys waiting for a window. Kanban WIP limits are Little's law applied.
What if throughput is not stable?
Use averages over a period long enough to smooth it — a month or a quarter. The law holds on average even when individual weeks vary.
How many items per person is reasonable?
One or two. Beyond three, context-switching cuts throughput as well as stretching cycle time, and the law says both get worse together.
Where these figures come from
- IEC 80000-13 — Information science and technology (quantities and units) — the decimal (kB, MB) versus binary (KiB, MiB) prefixes used throughout
- RFC 4632 — Classless Inter-domain Routing (CIDR) — the address-plan arithmetic behind the subnet calculator
- RFC 1918 — Address Allocation for Private Internets — the private ranges the subnet calculator recognises
- NIST SP 800-63B — Digital Identity Guidelines, Authentication — length over composition rules; the basis of the password guidance here
- NIST SP 800-57 Part 1 — Recommendation for Key Management — key-strength comparisons used by the key-space calculator
- National Cyber Security Centre — password guidance — UK national guidance on password policy
Last checked: September 2026. Units follow the SI decimal convention (IEC 80000-13 defines the binary alternatives); network and security figures cite the defining standard.