What is Two-bin system?

For a small Shopify store, a two-bin system works well for cheap, steady-selling items like packaging, labels, or small parts you keep in a stockroom. You do not need software or forecasts. The empty bin is the signal to reorder, and the second bin acts as your buffer while you wait for the supplier.

To use it, split your stock into two equal bins sized so that one bin covers your lead time plus a bit extra. When bin one runs out, place an order for a full bin's worth and start using bin two. By the time bin two is empty, the new order should have arrived and refills both bins.

Formula

Example

A candle store uses 300 wick clips a month, about 10 a day. The supplier lead time is 6 days. Bin size is set at 10 x 6 = 60, plus 20 extra for safety, so each bin holds 80 clips. When bin one is empty, the store orders 80 more clips and switches to bin two while waiting for delivery.

Common mistakes

• Making both bins too small, so bin two runs out before the new order arrives.
• Forgetting to actually place the order when bin one empties, since there is no automatic alert.
• Using it for items with uneven or seasonal demand, where fixed bin sizes stop matching actual usage.

Two-bin system and SteadyShelf

SteadyShelf is built for variant-level forecasting and supplier order timing across many SKUs, so it suits stores that have outgrown manual two-bin tracking on the shelf.

SteadyShelf is launching on the Shopify App Store. Join early access to get the install link first.

Related terms

Reorder point · Safety stock · Kanban · Par level

Full inventory glossary

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