Inventory Buffer Calculator

How much stock should you keep? Calculate your safety stock level based on daily sales, viral spike risk, and FBT replenishment lead time.

2026 update: FBT is now mandatory for US sellers. Replenishment lead time to FBT warehouses is typically 3–7 business days. Stockouts during viral spikes cause out-of-stock cancellations which hurt your SPS.

Average daily sales (units)

Replenishment lead time (days) FBT avg: 5 days

Viral spike multiplier how big could a spike be?

Viral probability in next 30 days

Unit cost / COGS ($)

FBT storage cost per unit/month ($) after 30 free days

Inventory Recommendation

Enter your numbers above.