Kanban guide · Lean foundations
Just-in-Time (JIT): How It Works, Benefits and Risks
Just-in-Time (JIT) means producing or delivering exactly what is needed, when it is needed, in the quantity needed. It is one of the two pillars of the Toyota Production System, alongside jidoka (building quality in).
Key takeaways
- JIT produces only what is needed, when needed.
- Kanban signals and small batches make it work.
- It cuts waste but needs reliable supply, so many firms keep strategic buffers.
How JIT works
- Pull from demand: each process makes only what the next process has used; see pull vs push.
- Kanban signals: cards or containers tell upstream processes what to replenish; see Kanban inventory management.
- Small batches: reduce batch sizes to keep flow smooth.
- Quick changeovers: make switching between products fast so small batches are economical.
- Reliable suppliers: frequent, dependable deliveries.
Benefits
- Lower inventory and storage costs.
- Less waste from obsolete or damaged stock.
- Problems surface quickly because there is little buffer to hide them.
- Faster response to changes in demand.
Risks and limits
JIT depends on stable demand and reliable suppliers. When supply chains are disrupted, low inventory can halt production. After recent global supply disruptions, many companies have adopted a "just-in-case" balance: JIT for most items, with strategic buffers for critical parts.
JIT thinking in projects
- Plan in detail only just before work starts, as in Agile release planning.
- Refine backlog items just in time for the next iteration, not months ahead.
- Make decisions at the last responsible moment.
- Avoid large stockpiles of half-finished work.
Frequently asked questions
Who invented Just-in-Time?
JIT was developed at Toyota, with Taiichi Ohno as its best-known architect, from the late 1940s onwards.
What is the difference between JIT and Kanban?
JIT is the goal of producing only what is needed when needed; kanban is the signalling system that makes JIT work.
What is Just-in-Time?
Just-in-Time (JIT) is a production approach in which materials and parts are made or delivered only when needed, in the quantity needed, to minimise inventory and waste.
What are the benefits of Just-in-Time?
Lower inventory and storage costs, less waste and obsolescence, and faster exposure of quality and process problems.
What are the risks of Just-in-Time?
With little buffer stock, supply disruptions, demand spikes or quality failures can halt production quickly. JIT depends on reliable suppliers and stable processes.
Which companies use Just-in-Time?
Toyota is the classic example, and the approach has been widely adopted across the automotive industry and many other manufacturers.
Is Just-in-Time still used after supply chain disruptions?
Yes, but many firms now combine it with strategic buffer stock for critical parts, balancing efficiency against resilience.
What is the difference between JIT and Just-in-Case?
Just-in-Case holds extra inventory to protect against uncertainty. JIT keeps inventory low and relies on smooth, pull-based supply.
How does JIT apply to project management?
Teams apply JIT ideas by detailing and starting work only when it is needed, keeping backlogs lean and pulling work as capacity frees up, as in Kanban.
Is Just-in-Time a pull system?
Yes. Production is triggered by actual downstream demand rather than a forecast, which is the definition of pull.
What are the prerequisites for Just-in-Time?
Reliable suppliers, consistent quality, short set-up times, steady demand and a disciplined signalling system such as kanban cards.