Reorder Point Calculator
Calculate when to reorder, how much to order, and what it costs — instantly. No login, no spreadsheet required.
Reorder Calculator
Enter your inventory and cost parameters to calculate reorder point, quantity, and timing
Results are estimates for planning purposes. Actual reorder timing may vary based on demand volatility, supplier reliability, and storage constraints. Consult your procurement team before changing reorder policies.
How to Use the Reorder Point Calculator
The Reorder Calculator tells you when to order (reorder point), how much to order (reorder quantity), and how long until you hit that trigger point. All three numbers together define a complete reorder policy for any SKU.
Inputs Explained
Current Inventory Level — Your on-hand units right now. The calculator uses this to tell you how many days until you hit your reorder point.
Average Daily Usage — How many units you consume per day on average. If you think monthly, divide by 30. Seasonal businesses should use the season's average, not the annual average.
Lead Time — Days from placing a purchase order to receiving inventory. Include all delays: supplier processing, manufacturing, transit, and receiving. For variable lead times, use the 75th percentile (not the average) for a more conservative policy.
Safety Stock Days — Extra coverage days to buffer against demand spikes and late deliveries. Defaults to 7 days. Increase this for critical items or unreliable suppliers. A reasonable range is 3–14 days depending on item criticality.
Min Order Quantity (MOQ) — Your supplier's minimum per order. When MOQ exceeds your calculated EOQ, the calculator uses MOQ and shows the carrying cost penalty. Leave blank if no MOQ applies.
Order Cost & Unit Cost — Order cost is the fixed cost of placing each purchase order (buyer time, system processing, incoming inspection). Unit cost is your purchase price. Both drive the EOQ calculation.
Understanding the Reorder Point Formula
When your on-hand inventory drops to the ROP, place a new order. The logic: at the ROP, you have exactly enough inventory to cover demand during the lead time, plus a buffer. If daily usage is 25 units, lead time is 10 days, and safety stock is 7 days × 25 = 175 units, your ROP = (25 × 10) + 175 = 425 units.
The Reorder Quantity Formula (EOQ)
EOQ finds the order size that minimizes total inventory cost. Larger orders mean fewer orders per year (lower ordering cost) but higher carrying costs. EOQ is the point where those two costs balance. If your supplier's MOQ exceeds EOQ, the calculator shows the MOQ instead and flags the excess carrying cost.
Color-Coded Urgency Status
- 🔴 Order Now — Your current inventory is at or below the reorder point. Place an order immediately or risk a stockout before your next delivery arrives.
- 🟡 Approaching Reorder — You'll hit your reorder point within the next 14 days. Begin your ordering process — especially for suppliers with long lead times or high seasonal demand.
- 🟢 Healthy — You have adequate buffer. Monitor regularly and use the "days until reorder" figure to schedule your next purchase order.
Who Should Use This Tool
- Purchasing managers setting reorder policies for each SKU
- Warehouse managers tracking when to replenish bins
- Operations analysts building procurement calendars
- Small business owners replacing gut-feel ordering with data
- ERP implementation teams validating system reorder parameters
Frequently Asked Questions
A reorder point calculator determines the inventory level at which you should place a new purchase order. It factors in your average daily usage, supplier lead time, and safety stock buffer to ensure you never run out before the next order arrives. The formula is: ROP = (Average Daily Usage × Lead Time) + Safety Stock.
Reorder quantity is calculated using the Economic Order Quantity (EOQ) formula: √(2 × Annual Demand × Order Cost ÷ (Unit Cost × Carrying Cost %)). EOQ minimizes total inventory costs by balancing the trade-off between ordering frequently (lower carrying cost, higher ordering cost) and ordering in bulk (lower ordering cost, higher carrying cost).
Safety stock is a buffer of extra inventory held to protect against demand spikes and lead time delays. It's added on top of cycle stock to determine the reorder point. Safety stock days defines how many additional days of demand you want as a buffer above the lead time demand. Typical values range from 3 days (stable, non-critical) to 14+ days (variable demand, critical items).
Days until reorder is how many days from now until your current inventory level reaches the reorder point, based on your average daily consumption. It tells you when to place your next purchase order. A value of 0 or negative means you're already at or below the reorder point — order immediately.
Optimal reorder frequency depends on your EOQ and annual demand. High-value, high-velocity items often warrant more frequent, smaller orders to reduce carrying costs. Low-cost, low-velocity items may benefit from larger, less frequent orders. The calculator shows your annual order frequency — typical ranges are 4–12 orders per year for most industrial SKUs.
Minimum order quantity (MOQ) is the smallest quantity your supplier will accept per order. When MOQ exceeds your EOQ, you must order at least the MOQ, which increases carrying costs above the theoretical minimum. The calculator uses the higher of EOQ or MOQ as the reorder quantity and shows the adjusted annual cost accordingly.