Amazon Sales & Inventory Demand Calculators
Forecast monthly sales volume and optimize inventory replenishment. Estimate sales from Best Sellers Rank (BSR), calculate replenishment reorder triggers, and project annual revenue growth.
Calculators in this Category
BSR Sales Estimator
Estimate monthly unit sales volume and revenue based on Amazon Best Sellers Rank (BSR) and category curves.
Revenue Estimator
Project monthly, quarterly, and annual revenue growth based on unit volume and selling price forecasts.
Reorder Point Calculator
Calculate inventory replenishment triggers and safety stock buffers based on daily sales velocity and lead times.
Restock Quantity Calculator
Determine exact purchase order unit volume based on sales velocity, lead times, and target days of inventory cover.
Who Should Use These Tools
Supply Chain Directors
Prevent costly out-of-stock events and optimize purchasing capital.
Amazon Sellers & Resellers
Evaluate competitor monthly sales volume using category BSR curves.
Inventory Analysts
Determine reorder point triggers and safety stock days of supply.
Brand Founders
Model multi-month revenue growth trajectories and cash flow requirements.
How to Use These Calculators
Input BSR Rank or Sales Velocity
Enter Best Sellers Rank (BSR) for sales estimates, or enter average daily unit sales.
Provide Supplier Lead Times
Input manufacturing production time and sea/air freight lead times in days.
View Reorder Triggers & PO Volume
Review your calculated reorder point, safety stock days, and exact purchase order units.
Optimizing Amazon Sales Forecasting & Inventory Replenishment
Inventory management on Amazon FBA is a delicate balance between avoiding stockouts (which kill keyword ranking) and avoiding overstocking (which incurs storage fees and low-inventory surcharges).
1. Estimating Monthly Sales from Best Sellers Rank (BSR)
Amazon BSR reflects real-time sales velocity relative to other products in the same category. Mapping BSR to logarithmic sales curves provides accurate monthly unit estimates.
2. The Reorder Point Formula
Reorder Point = (Daily Sales Velocity × Lead Time in Days) + Safety Stock Units. Placing purchase orders when total inventory drops to this threshold prevents stockouts during transit.
3. Calculating Optimal Restock Quantity
Restock Quantity = (Target Supply Days × Daily Sales Velocity) − Current FBA Stock − Inbound Inventory. This ensures purchase orders supply exactly enough stock to hit target inventory cover.
2026 Reference & Rate Breakdown Table
| Metric | Formula | Operational Purpose |
|---|---|---|
| BSR Sales Estimate | Category BSR Logarithmic Curve | Competitor research & market sizing |
| Reorder Point | (Daily Sales × Lead Time) + Safety Stock | Trigger for placing supplier purchase orders |
| Restock Quantity | (Target Days × Daily Sales) − Stock | Exact unit quantity to order from factory |
| Safety Stock | Daily Sales × Desired Buffer Days | Buffer against freight or factory delays |
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Frequently Asked Questions
Common questions regarding Sales & Demand calculations and 2026 fee schedules