Size cards and zones from demand and lead time.
Use it when you set up or resize a kanban loop. It turns daily demand, replenishment lead time and container quantity into the number of cards, safety stock, reorder point and red, yellow and green zones for each item.
Paste four columns from Excel. Lead time is the whole replenishment cycle: order, supplier delivery and receiving.
Adjusted demand = demand × (1 + buffer) × (1 + safety). Kanbans = adjusted demand × lead time ÷ quantity per kanban, rounded up. Safety stock = (adjusted demand − demand) × lead time. Reorder point = demand during lead time + safety stock.
A kanban loop needs enough cards to cover demand while a replenishment order is on its way, plus a buffer for variation.
Number of kanbans = (daily demand × lead time in days × (1 + safety factor)) ÷ container quantity, rounded up.
Usage is 200 pieces a day, the supplier lead time is 3 days, the safety factor is 20% and each bin holds 100 pieces. (200 × 3 × 1.2) ÷ 100 = 7.2, so you need 8 kanban bins in the loop.
Divide the demand during replenishment lead time, plus safety stock, by the container quantity and round up. The calculator does this for you.
A simple kanban with two containers: when the first bin is empty it triggers a reorder while you use the second bin. It suits low-cost, high-use parts.
Review monthly or whenever demand or lead time changes by more than about 20%.