JITJust-in-Time Inventory
Just-in-Time inventory is a strategy of ordering stock to arrive precisely when needed — minimising storage costs and tied-up capital — rather than holding large safety buffers.
What is JIT?
Just-in-Time (JIT) inventory management originates from Toyota's manufacturing philosophy and means maintaining minimum stock levels, with new inventory arriving precisely when existing stock is depleted. Applied to ecommerce, JIT means ordering frequently in smaller quantities matched to actual sales velocity, rather than holding large bulk inventory buffers.
The benefits of JIT are capital efficiency and reduced storage costs. Cash not tied up in excess inventory can fund advertising, product development, or other growth initiatives. For Amazon FBA sellers, minimising excess inventory also protects IPI scores and avoids long-term storage fees on slow-moving stock.
The risks of JIT are supply chain vulnerability. Any disruption — delayed shipments, factory shutdowns, freight backlogs — can cause stockouts. JIT requires highly reliable suppliers, accurate demand forecasting, and disciplined reorder point management. It works best for stable, predictable-selling SKUs with reliable supply chains; it fails dangerously for products with erratic demand or long lead times.
Why it matters for sellers
For growing ecommerce brands, cash is the primary constraint. A $200,000 inventory position that could be reduced to $80,000 with tighter JIT management frees $120,000 for advertising or new product development. This capital efficiency advantage compounds — brands that turn inventory fast grow faster.
How to use JIT
Calculate reorder point for each SKU: (Average daily sales × Lead time in days) + Safety stock. Safety stock = (Maximum daily sales × Maximum lead time) − (Average daily sales × Average lead time). Set automatic reorder alerts at this threshold in your inventory management system.
For Amazon FBA, maintain a minimum 30-day cover at FBA at all times to prevent stockouts (which hurt IPI and ranking). Use a 3PL or your own warehouse as a buffer: hold 30–60 days at FBA, with 60–90 days of additional buffer at your warehouse ready to ship to FBA.
Real-world example
A candle brand historically kept 120 days of inventory at FBA, tying up $180,000 in stock. After implementing JIT with accurate demand forecasting, they reduce to 45 days FBA + 30 days warehouse buffer. This frees $90,000 in working capital, which they allocate to new product launches. In 18 months they add 4 SKUs that collectively generate more revenue than the capital savings cost.
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Frequently asked questions about JIT
Is JIT inventory risky for Amazon FBA sellers?
Yes, if not managed carefully. Stockouts on Amazon hurt BSR, keyword ranking, and IPI simultaneously — the recovery cost often exceeds the storage savings. JIT on Amazon works best with reliable 30-day lead time suppliers and a domestic 3PL buffer to replenish FBA quickly.
What is the minimum safety stock I should keep?
Safety stock = (Maximum daily sales − Average daily sales) × Lead time. As a rule of thumb for Amazon FBA: maintain at least 14–21 days of safety stock at FBA beyond your reorder point. During Q4, extend this buffer to 30–45 days given Amazon's slower inbound processing times.
What tools help with JIT inventory management?
Linnworks and Skubana (now Extensiv) are popular multichannel inventory platforms. Inventory Planner (Shopify app) forecasts demand and sets reorder points automatically. Amazon's own Restock Inventory tool in Seller Central provides basic reorder recommendations based on sales velocity and lead times.