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Restock Planner

Calculate Reorder Point (ROP) and Safety Stock based on sales, production, and shipping lead times to avoid stockouts.

Sales & Lead Time Parameters
50 days
Total Lead Time
1,420 units
Reorder Point (ROP)
420 units
Safety Stock
1,280 units
Suggested Order Qty
Restock Timeline
PhaseDaysCumulativeAction
Production15 days15 daysPlace order immediately
Shipping30 days45 daysIn transit, monitor stock
Inbound5 days50 daysArrived, waiting to be received
Safety Stock Buffer14 days64 daysBuffer period, regular sales
💡 ROP = Daily Sales × Total Lead Time + Safety Stock. Order when stock drops to ROP.
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Running out of stock on Amazon or any e-commerce platform can cost far more than a few lost sales—it can trigger ranking drops, loss of the Buy Box, and long-term damage to conversion rates. But overstocking ties up working capital and incurs storage fees. The Restock Planner calculates your Reorder Point (ROP) and Safety Stock based on your actual sales velocity, demand variability, and the full lead time from production through shipping to platform inbound processing. By entering your real operational parameters, you get data-driven replenishment targets that buffer against lead time volatility without over-ordering.

Understanding Lead Time Components

Total lead time is not just shipping time. For most cross-border e-commerce sellers, the full replenishment cycle includes three phases: production or sourcing days (the time your supplier needs to manufacture, source, or pack the order), shipping days (transit time by sea, air, or express courier from origin to destination), and inbound processing days (the time the fulfillment center or platform warehouse takes to receive, inspect, and make inventory available for sale). Missing any component—for example, overlooking that Amazon FBA inbound processing can take 7 to 21 days during normal periods or longer during Q4—leads to understated lead times and unexpected stockouts. Always base these inputs on your historical actuals rather than optimistic estimates, and build in a margin for the variability you have actually experienced with each supplier and carrier.

Reorder Point (ROP) and Safety Stock Explained

The Reorder Point (ROP) is the inventory level at which you should place a new purchase order so that incoming stock arrives before you run out. The formula is: ROP = Daily Sales × Total Lead Time + Safety Stock. Safety stock is a buffer that accounts for demand variability and lead time uncertainty. This calculator uses a demand variability coefficient (1 = stable, 2 = seasonal peak, 3 = promotional event) to scale the safety stock proportionally. A coefficient of 2 doubles the base safety stock relative to coefficient 1, giving you extra runway during high-demand periods. Setting your target safety days—the minimum number of days of stock you always want on hand—adds another protection layer on top of the statistical calculation. Taken together, ROP and safety stock give you a clear trigger point and a minimum threshold that should never be breached.

Restock Planning for Amazon FBA Sellers

Amazon FBA sellers face unique challenges: inbound processing times fluctuate by season, FBA inventory can be split across fulfillment centers, and restocking too frequently incurs multiple inbound shipment setup fees. The recommended workflow is as follows. First, check your sales velocity in Seller Central—use a 30-day rolling average for stable products, or a 14-day window for fast-moving seasonal items. Second, set production days to the actual lead time your supplier quotes for your order quantity, not a best-case scenario. Third, use shipping days that match your chosen transport mode: sea freight typically runs 25 to 35 days to the US or EU, while air express runs 5 to 7 days. Fourth, add 14 to 21 days for Amazon inbound processing during normal periods, or 21 to 30 days during Q4 peak season. Combine this tool with our Inventory Turnover Calculator to measure how efficiently your working capital is deployed across your entire SKU portfolio.

How to Use the Restock Planner

  1. Enter your average daily sales in units. Use actual data from the past 30 days for stable products, or a shorter window during promotional spikes.
  2. Set the demand variability coefficient: 1 for stable products, 2 for seasonal or promotional peaks, 3 for extreme events like Prime Day or Black Friday.
  3. Input production days (supplier lead time), shipping days (transit time), and inbound processing days (warehouse or FBA receiving time).
  4. Enter your target safety days—the minimum number of days of inventory you want to maintain as a buffer against unexpected delays.
  5. Review the Reorder Point, Safety Stock, and Suggested Order Quantity. Place a new order when your current inventory count drops to the ROP level.

Frequently Asked Questions

What is a Reorder Point (ROP) and how is it calculated?
The Reorder Point is the inventory level at which you should place a new purchase order. It is calculated as: ROP = Daily Sales × Total Lead Time + Safety Stock. The goal is to have enough inventory on hand to cover all the time between placing and receiving an order, plus a safety buffer. When your live inventory count drops to the ROP, you should place a new order immediately to avoid a stockout.
How do I determine the right demand variability coefficient?
Use coefficient 1 (stable) for products with consistent day-to-day sales. Use 2 (peak) when you are entering a seasonal period—for example, winter apparel in October through December or summer sports gear in April through June. Use 3 (event) only for extreme promotional events like Prime Day or a major platform sale where you expect sales to spike two to three times or more within a short window. A higher coefficient increases safety stock, protecting you during volatile demand at the cost of a slightly higher inventory investment.
Why does the calculator include inbound processing days separately?
Inbound processing—the time from when your goods arrive at the fulfillment center to when they appear as available inventory—is frequently overlooked but can be significant. At Amazon FBA this can range from 3 days during quiet periods to 3 weeks or more during Q4. If you count only shipping days, your ROP will be understated and you risk stockouts while inventory sits in an inbound queue. Enter realistic inbound days based on your historical experience with each marketplace and season.
What is safety stock and how much should I carry?
Safety stock is a buffer against two types of uncertainty: demand spikes that exceed your daily average, and lead time delays that push back receipt of new stock. The right level depends on your product's sales variability, supplier reliability, and the business cost of a stockout. For high-margin or search-rank-sensitive products, err on the side of more safety stock. For low-margin or slow-moving items, minimize safety stock to reduce storage fees. Use the demand variability coefficient and target safety days together to tune the level to your actual risk tolerance.
My lead time exceeds 60 days—what strategies should I consider?
Lead times over 60 days significantly increase both safety stock requirements and working capital tied up in orders in transit. Consider using air freight for urgent or high-turnover SKUs to cut shipping days; establishing overseas warehouse inventory to reduce effective replenishment lead time to a few days for platform fulfillment; negotiating better production lead times with your supplier, particularly if you share rolling forecasts; and carrying a larger safety stock buffer proportional to your total lead time, which this calculator already computes when you enter longer values.

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