Doesn't JIT increase delivery risk?

Yes, on an unreliable supply chain. On a reliable one, it reduces risk by exposing problems early. The honest answer is that JIT magnifies whatever your supply chain already is — good or bad. Don't adopt JIT to fix a broken supply chain.

How much inventory should we hold under JIT?

Enough to absorb realistic supplier variability and no more. For high-volume reliable items, 2–3 days. For critical-path items with single-source supply, 5–10 days. Zero stock is rarely the right answer outside Toyota plants.

Is JIT only for big projects?

No — small projects with no storage space benefit most. The principles scale down to a single fit-out crew, and the savings are proportionally larger because small projects often pay premium storage rents.

How does JIT interact with last-mile traffic restrictions?

It depends on city logistics. Dense urban projects often combine JIT with consolidation centres outside the city, with timed shuttle deliveries through the restricted zone. Treat the logistics chain as a sequence of JIT hand-offs, not one long delivery.

Can JIT survive supplier shocks (pandemic, port strikes)?

Less well than buffered supply chains — that is the trade-off. Mature JIT programmes maintain a small "strategic stock" of long-lead and single-source items as deliberate insurance. JIT does not mean zero resilience; it means resilience by design, not by accident.

Delivery-window adherence (% of deliveries inside the planned window), inventory days on site, double-handling incidents, and the rate of work stoppages caused by missing material. Together those four numbers describe the health of a JIT regime.

How is JIT different from Kanban?

Kanban is a signalling and visualisation system that often triggers JIT delivery. JIT is the delivery practice; Kanban is one (very common) way to trigger it. Many teams run JIT without Kanban (scheduled windows) and Kanban without strict JIT (work pulled but not material).

What's the biggest cultural change required?

Trust. Site teams stop hoarding only when they trust the supply chain; suppliers commit to windows only when they trust the demand signal. Building that trust takes months and is the real project, not the logistics design.

Which calculators on PMMilestone.org apply to Just-in-Time Delivery?

For Just-in-Time Delivery, the most relevant tools on the flagship platform are the EVM, SPI and CPI calculators on PMMilestone.org. They reproduce the formulas referenced in this entry against your own project data.

What is a common misconception about Just-in-Time Delivery?

That the topic is well-defined across all references. In practice, definitions vary between PMBOK, PRINCE2, AACE and ISO 21500 — this entry uses the definition most aligned with field practice on capital projects, and flags where the standards diverge.

Which related encyclopedia entries should I read alongside Just-in-Time Delivery?

Read Earned Value Management, Critical Path Method and the DCMA 14-point assessment next. The full A–Z is available in the PMMilestone Encyclopedia, and quick one-line definitions live in the PM Glossary on the flagship platform.

How does Dr. Hassan Eliwa's research treat Just-in-Time Delivery?

Dr. Hassan Eliwa's research focuses on owner-side project controls, schedule integrity and forensic delay analysis on capital construction and power programmes. Just-in-Time Delivery is treated through that lens — what a planning or controls engineer is expected to do with it on a live project, not its textbook definition alone. See the full research library at PMMilestone Research Articles.

How is Just-in-Time Delivery defined on PMMilestone Research & Insights?

A lean logistics approach where materials, components, or work items arrive exactly when needed for the next activity, reducing inventory, waste, and double-handling. For the full treatment, see the definition, principles, applications and related entries above — every encyclopedia entry follows the same research-grade structure.

Lean · Letter J

Just-in-Time Delivery

A lean logistics approach where materials, components, or work items arrive exactly when needed for the next activity, reducing inventory, waste, and double-handling.

By Dr. Hassan Eliwa, PhD · Founder of PMMilestone.org and PMMilestone.com · Updated 2026-06-23

Definition

Just-in-Time (JIT) delivery is a lean logistics strategy where materials, components, equipment or work items are delivered to the point of use precisely when they are needed for the next operation — not earlier, not later. The aim is to eliminate the waste, damage, double-handling, storage cost, and congestion that come with holding inventory on site or in process. Originating in the Toyota Production System, JIT has been adapted by lean construction, lean manufacturing, and agile software delivery.

The Lean Logic

Holding inventory feels safe — but lean accounting treats it as one of the seven wastes. Inventory hides production problems (you can paper over a slow trade by stockpiling material), ties up cash, occupies space, generates double-handling, and is at risk of damage and theft. JIT exposes those problems and forces the discipline of reliable upstream supply. It works only when the upstream supply chain is genuinely reliable; pushed onto an unreliable supply chain, it collapses spectacularly.

Real-World Construction Example

On a central-London tower with a footprint smaller than the basement floor plate, there was no room for material storage. The contractor ran a JIT regime: rebar bundles arrived at midnight for the next day's pour, MEP modules arrived in 4-hour windows tied to crane bookings, finishes arrived floor-by-floor. The price was a dedicated logistics manager and a strict supplier scorecard. The reward was a project that never lost a day to material shortage, congestion, or storage damage. The same approach on a less disciplined project would have been a disaster.

Real-World IT / Agile Example

The agile equivalent of JIT is pulling work into a sprint or onto a Kanban board only when capacity is free, instead of pre-loading the team with weeks of refined backlog. On a payments platform team, switching from "fill the sprint to 100% capacity" to a pull-based JIT model cut average cycle time by 35% and reduced context-switching dramatically. Stories sat refined-and-ready in the backlog; they were pulled to development only when a slot opened. Backlog refinement happened weekly, just-in-time.

Prerequisites for JIT to Work

Reliable upstream: suppliers or upstream teams that hit windows consistently.
Tight communication: changes in demand or sequence reach the supply chain in hours, not days.
Logistics discipline: delivery windows, sequencing, and inspections planned at the same fidelity as the work itself.
Buffer where it matters: JIT is not zero-stock; critical items still get safety stock. The discipline is about where the buffer sits.
Cost transparency: the savings on holding cost have to be reinvested in logistics capability, not silently pocketed.

Project Controls Perspective

Controls teams measure JIT success with two numbers: delivery-window adherence (deliveries arriving inside their planned window) and inventory days on site (how many days of forward material the site is holding). A mature JIT regime hits 95%+ window adherence with 3–5 days of inventory on the most critical materials. A failing regime hits 60% window adherence and either drowns in stock (defensive over-ordering) or starves regularly.

Common Mistakes

Adopting JIT without supplier reliability. The classic disaster: site empties its warehouse, supply chain stutters, work stops.
Treating JIT as cost-saving only. The point is flow and quality; the cost saving is a by-product.
No logistics manager. JIT needs a dedicated owner; bolted onto an existing project manager's role, it fails.
Hidden defensive buffers. Site teams stockpile quietly because they don't trust the process; the apparent JIT regime is a fiction.
JIT in software for poorly refined backlogs. Pulling a story that turns out to be unclear blocks the team — refinement still has to happen, just close to the pull point.
Confusing JIT with last-minute. JIT is precision timing; "last minute" is panic.

Expert Tips

Start with one material category. Pick the highest-volume, easiest-supplier item and pilot JIT there before extending.
Score suppliers on adherence, not price. A supplier who is 5% cheaper and hits 70% of windows costs more than one who is full price at 95%.
Build relationships, not just contracts. JIT runs on phone calls between people who trust each other.
Treat the delivery window as a hard constraint. Acceptance outside the window — even early — should be the exception, not the norm.
Measure inventory weekly. If days-on-hand creep up, JIT is quietly collapsing.

Key Takeaways

JIT is precision logistics, not last-minute logistics.
The benefits are flow, quality and exposure of upstream problems — not just inventory cost.
It requires reliable suppliers, tight comms, and dedicated logistics ownership.
Hidden buffers indicate the regime isn't working; treat them as a diagnostic.
The agile analogue — pull-based work delivery — applies the same discipline to software teams.

Related Encyclopedia Entries

Last Planner System — companion entry on a directly related concept.
Kanban — companion entry on a directly related concept.
WIP Limits — companion entry on a directly related concept.
Takt Time Planning — companion entry on a directly related concept.
Procurement Management — companion entry on a directly related concept.
Gemba Walk — companion entry on a directly related concept.

Frequently Asked Questions

Doesn't JIT increase delivery risk?
Yes, on an unreliable supply chain. On a reliable one, it reduces risk by exposing problems early. The honest answer is that JIT magnifies whatever your supply chain already is — good or bad. Don't adopt JIT to fix a broken supply chain.
How much inventory should we hold under JIT?
Enough to absorb realistic supplier variability and no more. For high-volume reliable items, 2–3 days. For critical-path items with single-source supply, 5–10 days. Zero stock is rarely the right answer outside Toyota plants.
Is JIT only for big projects?
No — small projects with no storage space benefit most. The principles scale down to a single fit-out crew, and the savings are proportionally larger because small projects often pay premium storage rents.
How does JIT interact with last-mile traffic restrictions?
It depends on city logistics. Dense urban projects often combine JIT with consolidation centres outside the city, with timed shuttle deliveries through the restricted zone. Treat the logistics chain as a sequence of JIT hand-offs, not one long delivery.
Can JIT survive supplier shocks (pandemic, port strikes)?
Less well than buffered supply chains — that is the trade-off. Mature JIT programmes maintain a small "strategic stock" of long-lead and single-source items as deliberate insurance. JIT does not mean zero resilience; it means resilience by design, not by accident.
How is JIT measured?
Delivery-window adherence (% of deliveries inside the planned window), inventory days on site, double-handling incidents, and the rate of work stoppages caused by missing material. Together those four numbers describe the health of a JIT regime.
How is JIT different from Kanban?
Kanban is a signalling and visualisation system that often triggers JIT delivery. JIT is the delivery practice; Kanban is one (very common) way to trigger it. Many teams run JIT without Kanban (scheduled windows) and Kanban without strict JIT (work pulled but not material).
What's the biggest cultural change required?
Trust. Site teams stop hoarding only when they trust the supply chain; suppliers commit to windows only when they trust the demand signal. Building that trust takes months and is the real project, not the logistics design.
Which calculators on PMMilestone.org apply to Just-in-Time Delivery?
For Just-in-Time Delivery, the most relevant tools on the flagship platform are the EVM, SPI and CPI calculators on PMMilestone.org. They reproduce the formulas referenced in this entry against your own project data.
What is a common misconception about Just-in-Time Delivery?
That the topic is well-defined across all references. In practice, definitions vary between PMBOK, PRINCE2, AACE and ISO 21500 — this entry uses the definition most aligned with field practice on capital projects, and flags where the standards diverge.
Which related encyclopedia entries should I read alongside Just-in-Time Delivery?
Read Earned Value Management, Critical Path Method and the DCMA 14-point assessment next. The full A–Z is available in the PMMilestone Encyclopedia, and quick one-line definitions live in the PM Glossary on the flagship platform.
How does Dr. Hassan Eliwa's research treat Just-in-Time Delivery?
Dr. Hassan Eliwa's research focuses on owner-side project controls, schedule integrity and forensic delay analysis on capital construction and power programmes. Just-in-Time Delivery is treated through that lens — what a planning or controls engineer is expected to do with it on a live project, not its textbook definition alone. See the full research library at PMMilestone Research Articles.
How is Just-in-Time Delivery defined on PMMilestone Research & Insights?
A lean logistics approach where materials, components, or work items arrive exactly when needed for the next activity, reducing inventory, waste, and double-handling. For the full treatment, see the definition, principles, applications and related entries above — every encyclopedia entry follows the same research-grade structure.

View the full FAQ page for Just-in-Time Delivery →