Replenishment cadence -- how often you place orders for a given product -- is one of the least examined variables in retail inventory management. Most buyers inherit a cadence from their organization or their predecessor and adjust it only when something breaks. But a cadence mismatch is one of the most common sources of both stockouts and excess inventory in multi-store retail, and it's worth examining systematically.
The core principle is straightforward: the frequency with which you order a product should be calibrated to how fast that product sells through. A product with a 4-day sell-through at a given location needs a different replenishment cadence than a product that takes 28 days to sell through at that same location. Applying the same weekly order cycle to both creates predictable problems in opposite directions.
Understanding Sell-Through Rate as the Governing Variable
Sell-through rate is typically expressed as a percentage over a time period: if you received 100 units of a product and sold 75 of them in a week, the weekly sell-through rate is 75%. For replenishment planning, a more operationally useful metric is days of supply, derived from current on-hand inventory divided by daily velocity. If you have 12 units on hand and the product sells 3 units per day, you have 4 days of supply remaining.
Your replenishment cadence needs to ensure that a new order arrives before days of supply hits zero, accounting for supplier lead time. If your supplier has a 5-day lead time and your product sells at 3 units per day, you need to be placing a new order when your on-hand count is at least 15 units (5 days times 3 units per day), plus whatever safety stock you maintain for demand variability.
This calculation is straightforward for a single product at a single location. It becomes complex when you're managing hundreds of SKUs across multiple locations, each with different velocity profiles and potentially different lead times from different suppliers.
The Mismatch Problems
Ordering too infrequently relative to sell-through rate. If a product sells through in 4 days and you order weekly, you are structurally guaranteed to stockout unless your order quantity is large enough to cover 3 days of the following week as well. This creates a choice between overstocking (ordering 10-11 days' worth instead of 7 days' worth) or accepting regular stockouts. Neither is ideal. The correct solution is to increase order frequency for this product.
Ordering too frequently relative to sell-through rate. A product with a 28-day sell-through rate doesn't benefit from weekly orders -- it just means you're placing 4 small orders per month instead of 1 appropriately sized order. The administrative overhead per order (purchase order processing, receiving, put-away) is the same regardless of order size. For slow-moving products, high-frequency small orders increase total handling cost without any inventory benefit. Monthly orders with appropriate lot sizes are almost always more efficient for slow-moving SKUs.
The broader pattern is that most buyers apply a uniform cadence across their entire SKU portfolio because it simplifies the order schedule. This works reasonably well for products whose sell-through rate aligns with the chosen cadence. It works poorly for the outliers at both ends of the velocity spectrum.
Segmenting Your SKU Portfolio by Velocity Tier
A practical approach to cadence optimization is to segment your active SKU portfolio into velocity tiers and assign a cadence to each tier rather than to each individual SKU. The tiers and cadences don't need to be elaborate:
- High velocity (daily sales >5 units at a given location): Daily or twice-weekly replenishment check, orders placed as soon as days of supply drops below lead time plus safety stock. For products at this velocity, you're essentially running a continuous replenishment model.
- Medium velocity (1-5 units per day): Weekly replenishment review. Most products fall in this tier. Weekly ordering works well as long as order quantities are calibrated to actual velocity rather than a fixed par level.
- Low velocity (less than 1 unit per day average): Bi-weekly or monthly review. Carry enough safety stock to survive 2-3x average demand in a given week, since demand is irregular. Don't over-order -- the carrying cost risk is higher than the stockout risk for truly slow-moving products.
The exact thresholds depend on your supplier lead times, your storage constraints, and the nature of your product mix. But the principle of aligning cadence to velocity tier is almost universally applicable.
Location-Level Cadence vs. Chain-Wide Cadence
A complication for multi-store retailers is that the same SKU may fall into different velocity tiers at different locations. Your flagship downtown store might move 8 units per day of a product that your neighborhood location sells at 1.5 units per day. Chain-wide, that averages to about 5 units per day -- medium velocity. But Location A needs high-velocity treatment (daily or twice-weekly orders) while Location B can be served comfortably with monthly orders.
Applying the chain-average cadence to both means Location A gets under-served and Location B gets over-served. The appropriate solution is location-level cadence assignment -- which adds complexity to the order schedule but substantially improves inventory performance for the high-velocity outlier locations that are usually also your highest-revenue stores.
This is one of the operational reasons why store-level demand forecasting is more useful than chain-level forecasting: it gives you the per-location velocity data needed to make sensible cadence assignments, rather than relying on an average that accurately describes no individual location.
Cadence and Supplier Minimums: The Constraint You Can't Always Ignore
Cadence decisions don't happen in a vacuum. Supplier minimums -- minimum order quantities, minimum order values, or fixed delivery schedules -- constrain what cadences are actually available to you. A supplier who delivers once every two weeks on a fixed schedule doesn't give you the option of twice-weekly orders, regardless of your velocity data.
When supplier constraints prevent you from matching cadence to velocity, the practical response is to increase your safety stock buffer for products at that supplier that run at high velocity. You can't order more often, so you need a larger on-hand cushion to survive the full delivery cycle. This increases carrying costs, but it's the correct trade-off when the alternative is regular stockouts on high-velocity products.
The supplier relationship conversation is also worth having in this context. If you can demonstrate consistent, accurate ordering and reliable payment, some suppliers will offer more flexible delivery options to their better customers. Accurate demand data helps make that case: a buyer who can show a supplier exactly how much of their products each store sells per week is a buyer who can negotiate for delivery schedules that match actual operational needs.
