| Inventory Sourcing Cost |
Variable |
Model at 12.0% of first-year revenue, so it rises with product sales. |
Treating inventory buys as fixed overhead and overstating margin at higher volume. |
| Inbound Freight and Tariffs |
Variable |
Apply 3.0% of first-year revenue as a sales-linked landed-cost charge. |
Leaving tariffs out of unit economics until cash is already tight. |
| Shipping and Fulfillment |
Variable |
Use 4.0% of first-year revenue because orders create packing and shipment activity. |
Counting customer delivery work as free once the warehouse is staffed. |
| E-commerce Payment Processing |
Variable |
Apply 2.9% of first-year revenue to each online sale. |
Using gross sales as contribution before card fees clear. |
| Warehouse Rent |
Fixed |
Include $6,500 per month in fixed overhead during the launch planning range. |
Spreading rent per unit and missing the monthly cash hurdle. |
| Marketing and SEO Agency Retainer |
Fixed |
Include $3,000 per month before discretionary campaign spend. |
Blending the retainer with media spend and hiding the true fixed base. |
| Utilities and Warehouse Maintenance |
Semi-variable |
Start with the $1,500 monthly base, then add usage pressure as warehouse activity grows. |
Assuming power, repairs, and maintenance stay flat at peak shipment volume. |
| Year 1 Payroll |
Semi-fixed |
Use $300,000 per year, or $25,000 per month, until headcount steps up. |
Modeling payroll as a percent of revenue instead of staffing capacity blocks. |