Spring Festival Supply Buffer Calculator
Every year Chinese factories close for Spring Festival, and the true gap is longer than the public holiday because workers return in waves. If you buy from China, you need extra stock before the closure. This tool sizes it from demand, lead time and the shutdown length.
Your numbers
Include factory closure, staggered worker return and slow restart. Three to five weeks is common.
Your results
Assumes normally distributed weekly demand and a deterministic shutdown length. Confirm the real closure dates with each supplier and your sub-tier chain.
Extra inventory vs shutdown weeks
Sweeps Effective shutdown and ramp-up from 0 to 8, holding your other inputs fixed.
Supplier calendar automation
Optional: we can look at how supplier calendars and holiday shifts are handled in your planning run.
Optional. The tool and every export work without this. No spam.
How to use it
Enter weekly demand and its standard deviation, the supplier lead time, and the effective shutdown plus ramp-up in weeks. Pick a service level. The tool gives the pre-build quantity that covers the gap, the extra safety stock caused by the longer lead time, and the value and holding cost of the total. Compare against the cost of a line stoppage or air freight to decide how much risk to carry.
The math
Pre-build equals weekly demand times shutdown weeks, because the line consumes stock while no supply arrives. Safety stock follows the standard formula z times sigma times the square root of lead time. During the holiday window the lead time is longer, so the safety stock is higher. The extra safety stock is the difference between the two. Total extra inventory is pre-build plus that difference.
- Pre-build = weekly demand x shutdown weeks
- Safety stock = z x sigma x sqrt(lead time weeks)
- Holiday lead time = normal lead time + shutdown weeks
Common mistakes
Ordering late is the usual failure. To receive stock before closure, orders must be placed one full lead time earlier, so planning starts in the autumn. Another mistake is covering only the public holiday and ignoring the slow return, or forgetting that sub-tier suppliers close too. In your ERP, load the shutdown as a supplier calendar so MRP shifts planned orders automatically, and review open purchase orders for due dates inside the closure.
Frequently Asked Questions
How long should I assume the shutdown lasts?
Ask each supplier. The statutory holiday is about a week, but many factories close longer and take weeks to regain full output. Three to five weeks of effective impact is a typical planning range.
Why does safety stock increase?
Safety stock grows with the square root of the exposure period. A longer effective lead time during the holiday window means more uncertainty over that period, so the buffer rises even if demand stays the same.
Should I pre-build everything?
Not necessarily. Focus on single-source, high-impact and long lead items. Cheap bulky parts may cost too much to hold, so compare holding cost with the cost of a stoppage item by item.
Does it handle demand spikes before the holiday?
No. If your customers also pull orders forward, raise the weekly demand or standard deviation to reflect it. The tool assumes steady demand with normal variation.
If you maintain supplier calendars and holiday overrides by hand, we can help automate calendar loading and flag at-risk purchase orders.
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