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Reorder Points and Reorder Quantity, Explained

How reorder point (when to order) and reorder quantity (how much) work together, and how to set both.

Published 2026-09-05 Last updated 2026-09-05 Last verified 2026-09-05 ● Evergreen review

Who this is for

Sellers who've calculated safety stock and now need to turn it into an actual ordering rule.

Time to complete

15 minutes

What you'll need

Your calculated safety stock figure, Average daily sales and average lead time, Supplier order-cost and per-unit holding-cost estimates (for the EOQ section)

Key terms

Reorder point, Reorder quantity, Economic order quantity (EOQ), Order-up-to level

Two separate questions, one system

"When do I order?" and "how much do I order?" are two different decisions that too often get conflated into a single vague habit ("I'll order more when it looks low"). Splitting them into an explicit reorder point and reorder quantity turns inventory replenishment from a judgment call into a rule you (or a system) can execute consistently.

Reorder point: when to order

Reorder point = (Average daily sales × Average lead time) + Safety stock.

This is the on-hand inventory level that should trigger a new purchase order — not "close to zero," but a level that still has enough runway to cover normal demand through the lead time, plus your safety buffer for the abnormal case.

Worked example, continuing from How to Calculate Safety Stock: average daily sales of 12 units, average lead time of 14 days, and a calculated safety stock of 294 units.

Reorder point = (12 × 14) + 294 = 168 + 294 = 462 units.

The moment on-hand inventory hits 462 units, that's your signal to place the next order — not a rough "getting low" feeling, and not "when I run out."

Reorder quantity: how much to order

Reorder point tells you when; reorder quantity tells you how much. Three common approaches, from simplest to most rigorous:

1. Fixed lot size. Order the same quantity every time — often set by a supplier's minimum order quantity (MOQ), a container/pallet fill quantity, or simple round numbers. Easiest to manage, least optimized for cost.

2. Order-up-to level. Order enough to bring on-hand-plus-on-order inventory back up to a target ceiling (often set as some multiple of your reorder point, or a fixed number of weeks of demand). Adjusts naturally with demand changes but requires recalculating the target periodically.

3. Economic order quantity (EOQ). A formula that balances ordering cost (the fixed cost of placing and receiving a PO, regardless of size) against holding cost (the cost of storing inventory) to find the order size that minimizes total cost.

EOQ = √(2DS ÷ H)

Where D = annual demand in units, S = fixed cost per order (freight, handling, admin), H = annual holding cost per unit (storage, insurance, capital cost, shrinkage — commonly estimated as a percentage of unit cost).

Worked example. Annual demand: 12 units/day × 365 days ≈ 4,380 units/year. Cost per order: $50. Annual holding cost per unit: $2.

EOQ = √(2 × 4,380 × 50 ÷ 2) = √(219,000) ≈ 468 units per order.

That means: rather than ordering small batches frequently (racking up order costs) or one huge batch annually (racking up holding costs), roughly 468 units per order minimizes your combined cost given these inputs.

Comparing the three methods

Method	Best for	Trade-off
Fixed lot size	New sellers, supplier-imposed MOQs, simplicity	Doesn't adapt to demand changes; can over- or under-order as sales shift
Order-up-to level	Sellers with fluctuating demand who want a simple adaptive rule	Requires periodic recalculation of the target ceiling
EOQ	Sellers who know their order and holding costs and want a cost-optimized quantity	More setup; less useful if your real constraint is a supplier MOQ larger than the EOQ result

When the "right" quantity conflicts with a supplier minimum

If your calculated EOQ or order-up-to quantity comes out below your supplier's MOQ, the MOQ wins — you can't order less than they'll sell you. In that case, either negotiate a lower MOQ, accept the extra holding cost of ordering more than optimal, or look for a supplier whose MOQ better matches your actual volume. Don't quietly round up to the MOQ without recognizing that you're now carrying extra holding cost as a result — it's often still the right call, just worth knowing the trade-off you made.

Reviewing both numbers together

Reorder point and reorder quantity should be reviewed on the same cadence as your safety stock recalculation — a stale reorder point paired with a fresh reorder quantity (or vice versa) can leave you ordering the right amount at the wrong time, or the wrong amount at the right time. Treat them as one system, reviewed together.

Common mistakes

Setting a reorder point once and never revisiting it as sales volume changes.
Ordering a fixed lot size well below the EOQ-optimal quantity, unknowingly paying more in cumulative order costs than necessary.
Confusing 'reorder point' (a trigger level) with 'reorder quantity' (an order size) and tracking only one of the two.
Not accounting for on-order (in-transit) inventory when checking against the reorder point, leading to duplicate orders.

Best practices

Check on-hand-plus-on-order inventory against the reorder point, not on-hand alone.
Recalculate reorder quantity whenever your order cost, holding cost, or demand volume shifts meaningfully.
Use EOQ as a starting point, then adjust for real-world constraints like MOQs and container fill quantities.
Review reorder point and reorder quantity together on the same schedule as your safety stock recalculation.

Checklist

Reorder point calculated from safety stock + average demand during lead time
Reorder quantity method chosen deliberately (fixed lot, order-up-to, or EOQ)
Supplier MOQ checked against the calculated reorder quantity
On-order inventory factored into the reorder-point trigger check
Both figures on a recurring review schedule

Related tools & guides

FAQs

Do I need EOQ if my supplier has a fixed MOQ well above what EOQ would recommend?

Not really — if the MOQ is your binding constraint, EOQ is mostly academic for that SKU. It's still useful for SKUs where you have real flexibility in order size, or as leverage when negotiating a lower MOQ.

How does this change across multiple marketplaces?

If inventory is pooled across channels, calculate one combined reorder point and quantity against total demand. If you're allocating separate stock per channel, see Multichannel Inventory Allocation for how to split a limited order across channels by contribution margin rather than just velocity.

Next recommended guide

Seasonal Inventory Planning

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