Inputs
Example Data Table
| Location | Inventory | Capacity | Weight | Safety | Min |
|---|---|---|---|---|---|
| Warehouse A | 900 | 600 | 1.00 | 45 | 100 |
| Warehouse B | 700 | 500 | 0.80 | 35 | 50 |
| Warehouse C | 500 | 400 | 0.60 | 25 | 0 |
Formula Used
How to Use This Calculator
- Enter the total demand you must fulfill.
- Choose a method: priorities, supply, capacity, or blended.
- Add locations with inventory, capacity, and optional minimums.
- Set safety reserves to protect against uncertainty.
- Click calculate, then review shares and utilization.
- Download results as CSV or PDF for reporting.
Demand signals and allocation goals
Demand allocation turns uncertain demand into an executable fulfillment plan. This calculator helps ecommerce teams split unit demand across warehouses, channels, or regions while preserving service levels. It is useful for flash sales, promotions, or weekly replenishment cycles where demand arrives faster than inventory moves. By blending priority weights with constrained supply, you can reduce overselling, protect strategic customers, and keep operations aligned with inventory reality.
Inputs that drive reliable decisions
Reliable allocation starts with clean inputs and clear assumptions. Total demand represents the units you plan to fulfill in the window, after expected returns and cancellations. Each location includes on-hand inventory, a safety reserve to buffer volatility, and an optional capacity cap reflecting pick, pack, dock, or carrier limits. Priority weights express business intent, such as subscription commitments, premium zones, or marketplace service targets. Minimum allocations protect key lanes. Confirm units, timing, and fulfillment scope before running.
Allocation logic and constraint handling
The model applies constraints before distributing demand, so allocations stay feasible. Effective Supply equals Inventory minus Safety Reserve, never below zero. Max Allocation is the minimum of Effective Supply and Capacity, with capacity ignored when set to zero. Minimum allocations are assigned first. Remaining demand is distributed proportionally using your selected method. The blended method normalizes weights and max supply, then combines them with alpha to balance policy and reality. Whole unit rounding uses largest remainder to preserve totals in tight capacity and low stock.
Operational insights from results
Results translate math into decisions and highlight tradeoffs. Allocation share shows how demand is split, while utilization shows how hard each site is pushed against its maximum. Remaining stock signals stockout risk after safety. When demand exceeds feasible supply, unmet demand is reported; with backorders enabled, a backorder quantity supports customer messaging and replenishment planning.
Governance and continuous improvement
Use the outputs to drive governance and continuous improvement. Review whether weights reflect margin, shipping promises, and cost-to-serve. Adjust safety reserves when lead times, supplier reliability, or demand variability change. Re-run scenarios with different rounding to understand sensitivity. Export CSV for planners and PDF for stakeholders, then document decisions for auditability. Track fill rate, backorder incidence, and exception overrides to improve the next cycle. Align allocations with merchandising calendars and carrier cutoff times.
FAQs
How is max allocation calculated for each location?
Max allocation equals the smaller of effective supply and capacity. Effective supply is inventory minus safety reserve. If capacity is set to zero, it is treated as unlimited, so max allocation follows effective supply.
When should I use the blended method?
Use blended when you want priorities to matter, but still respect real supply. Alpha controls the mix. Higher alpha favors weights; lower alpha favors constrained supply. It works well for multi-warehouse ecommerce routing.
Why do allocations not match my weights exactly?
Weights guide proportional distribution only after minimums and caps apply. If a location hits its max, remaining demand is redistributed to others. Safety reserves also reduce available supply, shifting the outcome.
What does utilization mean in the results?
Utilization is allocated units divided by the location’s max allocation. High utilization indicates a constrained site. Pair it with remaining stock to spot risk: high utilization and low remaining stock suggests near-term pressure.
How should I set safety reserve values?
Set safety to protect variability from lead time, forecast error, or returns. You can enter unit reserves per location, or leave safety at zero and use the default percentage. Review safety after demand shocks.
Can I export results for planning and reporting?
Yes. Download CSV for spreadsheets and bulk analysis. Download PDF for sharing with operations and leadership. Exports include inputs-derived results like allocated units, shares, remaining stock, and utilization.