What is Just-in-Time?

Just-in-Time (JIT) is an inventory management strategy that aligns raw material orders with production schedules so materials arrive exactly when needed in the manufacturing process. By minimizing inventory on hand, JIT reduces carrying costs, waste, and capital tied up in stock, but requires highly reliable suppliers.

JIT was developed as part of Toyota's Production System and revolutionized manufacturing worldwide. Instead of maintaining large safety stocks, JIT relies on precise demand forecasting, reliable suppliers, short lead times, and smooth production flows. The ideal state is zero inventory—every component arrives just as it is needed on the production line.

The benefits of JIT are significant: reduced warehousing costs, less capital tied up in inventory, fewer obsolete goods, quicker identification of quality defects (since there is no buffer stock masking problems), and more factory floor space. However, JIT assumes a stable, predictable environment and highly reliable suppliers.

The COVID-19 pandemic exposed JIT's vulnerability to supply chain disruptions. When semiconductor suppliers halted production, automakers using JIT had no buffer stock and had to idle factories for months. This has led many companies to adopt "Just-in-Case" strategies—maintaining strategic safety stocks for critical components while keeping JIT for others.

Real-world example

Toyota's JIT system kept only 2-4 hours of parts inventory at assembly plants. When the 2011 tsunami disrupted suppliers, Toyota lost an estimated $1.2B in production. They subsequently adopted a hybrid approach with strategic buffers for critical components.

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What is Just-in-Time?

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