BusyFella · Resources
BusyFella Calculation Methodology
BusyFella makes its calculation logic public so every result can be checked independently.
✓ Reviewed and updated 8 September 2026
BusyFella
Make the numbers talk
Core profitability formulas
Unit profitSelling price − Purchase cost
MarginUnit profit ÷ Selling price × 100
MarkupUnit profit ÷ Purchase cost × 100
Price from target marginCost ÷ (1 − target margin)
Calculation order used in Full Deal
- List adjustment. Any increase or decrease is applied to the starting list price.
- Successive discounts. Each discount is applied to the remaining value.
- Free goods. The discounted amount is spread across paid plus free units.
- Percentage fees. Tariffs and fees are applied to the discounted unit value.
- Freight. Total freight is divided by units and added per unit.
- Tax. Optional VAT is applied at the end. Users should keep purchase and selling tax treatment comparable.
Validation example
List price €100; discounts 20% and 10%; pay 10 units and receive 2 free; no fees, freight or VAT.
- After discounts: €100 × 0.80 × 0.90 = €72 per paid unit
- Amount paid for 10 units: €720
- Units received: 12
- Effective purchase cost: €720 ÷ 12 = €60 per unit
Accuracy and limitations
Inputs are processed in the browser and results are rounded for display. BusyFella is a decision-support tool, not accounting, tax or legal advice. Commercial agreements can define a different calculation order; when they do, the contract prevails. Report an unclear result through the contact page and include the inputs needed to reproduce it.