Reorder Point (ROP) Calculator

Determine exactly when to reorder stock to avoid stockouts and overstocking.

Inventory Variables

How many units of this product do you sell on an average day?
How many days does it take for a new order to arrive from your supplier?
Extra stock kept for emergencies (e.g., supplier delays or sudden demand spikes).

Your Ideal Reorder Point

900

Units

When your inventory level drops to 900 units, it is time to place a new order!

Lead Time Demand

700

(Sales while waiting)
Safety Buffer

200

(Emergency Stock)

ROP, Safety Stock & EOQ — Inventory Formulas

Reorder Point (ROP)
ROP = (Avg Daily Sales × Lead Time) + Safety Stock

Example: 50 units/day, 14-day lead, 200 safety → ROP = (50×14) + 200 = 900 units

Safety Stock Formula
SS = (Max Daily − Avg Daily) × Max Lead Time

Example: Max daily 80, Avg 50, Max lead 20 → SS = (80−50) × 20 = 600 units

Economic Order Qty (EOQ)
EOQ = √(2 × Annual Demand × Order Cost ÷ Holding Cost)

Example: 18,000 units/yr, Order cost ₹500, Holding ₹2/unit → EOQ = √(2×18000×500÷2) = 3,000 units

ROP Reference Table — At Various Demand & Lead Time Levels

Assumes safety stock = 20% of lead time demand. Adjust for your actual variability.

Daily SalesLead: 7 DaysLead: 14 DaysLead: 21 DaysLead: 30 Days
10 units/day84168252360
25 units/day210420630900
50 units/day4208401,2601,800
100 units/day8401,6802,5203,600
200 units/day1,6803,3605,0407,200
500 units/day4,2008,40012,60018,000

ROP = Lead Time Demand × 1.2 (includes 20% safety buffer). Use our calculator above for exact figures based on your max vs average demand variability.

Inventory Management Metrics — Quick Reference
MetricFormulaPurpose
ROP(Avg Sales × Lead Time) + Safety StockWhen to reorder
Safety Stock(Max−Avg Sales) × Max Lead TimeBuffer against uncertainty
EOQ√(2 × Demand × Order Cost ÷ Holding Cost)How much to order
Turnover RatioAnnual Sales ÷ Avg Inventory ValueInventory efficiency
Days Inventory365 ÷ Turnover RatioDays stock will last
Max Stock LevelROP + EOQ − (Min Sales × Min Lead)Upper inventory limit

ABC Analysis — Prioritize Your ROP Calculations

Not all SKUs need the same attention. Apply ABC classification before setting ROP for each item.

Class% of SKUs% of ValueROP Strategy
A Items10–20%70–80%Tight control, frequent review, lower safety stock %
B Items30%15–25%Moderate control, monthly review
C Items50–60%5–10%Bulk ordering, high safety stock, infrequent review
Consequences of Wrong ROP
ROP Too Low
Stockout → lost sales
Emergency purchases at premium
Customer churn
ROP Too High
Excess inventory → capital locked
Storage costs rise
Obsolescence / expiry risk
Industry Tip: Review ROP quarterly. Seasonal businesses (e.g., apparel, FMCG) should increase safety stock 4–6 weeks before peak season and reduce it post-peak to free up working capital.

Frequently Asked Questions

ROP is the inventory level that triggers a new purchase order. Formula: ROP = (Average Daily Sales × Lead Time in Days) + Safety Stock. Example: 50 units/day, 14-day lead time, 200 safety stock → ROP = 700 + 200 = 900 units. When your stock hits 900, immediately place a replenishment order.
Safety stock is buffer inventory against demand spikes and supplier delays. Formula: Safety Stock = (Max Daily Sales − Avg Daily Sales) × Max Lead Time. Example: Max 80 units/day, Avg 50 units/day, Max lead 20 days → Safety Stock = (80−50) × 20 = 600 units. A higher safety stock reduces stockout risk but increases holding costs.
Lead time = Supplier processing time + Manufacturing/preparation time + Transit/shipping time + Receiving/inspection time. Track actual lead times across 10+ orders and use the average. For critical SKUs, use the 90th percentile lead time (worst case) as your planning lead time.
EOQ = √(2 × Annual Demand × Ordering Cost ÷ Holding Cost per unit per year). It gives the optimal order quantity that minimizes total inventory cost. Example: Annual demand 18,000 units, order cost ₹500, holding cost ₹2/unit → EOQ = √(2×18000×500÷2) = 3,000 units. Order 3,000 units each time ROP is hit.
Recalculate quarterly for stable items, monthly for fast-moving or seasonal SKUs, and immediately after any significant change in: daily sales trend (>15% change), supplier lead time change, or new supplier onboarding. Seasonal businesses should increase safety stock 4–6 weeks before peak season.
ABC analysis classifies inventory by annual value: A-items (top 20% SKUs = 70–80% of value) need tight ROP control and low safety stock %; B-items (30% SKUs = 20% value) need moderate monitoring; C-items (50% SKUs = 5% value) can use bulk ordering with high safety stock. Apply rigorous ROP calculations only to A and B items to save time.
ROP too low → stockout during lead time → lost sales, emergency purchases at premium prices, customer churn. ROP too high → excess inventory → capital locked, higher storage costs, obsolescence/expiry risk for perishables. The correct ROP balances both risks. Track fill rate (% orders fulfilled from stock) — target 95–99% for A-items.
For seasonal items: use weighted average daily sales (higher weight on recent months) and increase safety stock multiplier to 1.5–2x during build-up season. For irregular demand: use statistical safety stock = Z × σ (standard deviation of lead time demand), where Z = 1.65 for 95% service level, 2.05 for 98%. A simple approximation: Safety Stock = 0.5 × Avg Lead Time Demand.
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