A discount changes the money retained from every affected sale. Additional orders must make up that difference, and any new costs, before the promotion improves the result you are measuring.
Work through a fictional workshop
A business sells a workshop seat for $120. The variable cost of serving a participant is $45. It currently sells 80 seats in a comparable period. Unit contribution is $75 and total contribution is 80 × $75 = $6,000.
A 15% discount lowers price to $102. If variable cost remains $45, the new contribution is $57 per seat.
| Offer | Price | Unit contribution | Volume | Total contribution |
|---|---|---|---|---|
| Current | $120 | $75 | 80 | $6,000 |
| Discount, assumed response | $102 | $57 | 100 | $5,700 |
| Discount, preservation threshold | $102 | $57 | 106 | $6,042 |
The exact threshold is $6,000 / $57 = 105.263… seats. The business therefore needs at least 106 whole seats: 26 more than before, or 32.5% extra volume. At 100 seats, revenue rises from $9,600 to $10,200 while total contribution falls by $300.
Check whether the volume can be delivered
If the workshop can serve only 100 seats in that period, the discounted offer cannot preserve the original contribution under these assumptions. More inquiries cannot create capacity beyond the limit. Extra sessions might be possible, but would introduce costs and a different operating scenario.
Connect the calculation to capacity measurement and the bottleneck tool. A promotion that is attractive in a price spreadsheet can fail when the delivery system cannot handle it.
Separate new demand from shifted purchases
Some discounted buyers might have paid full price anyway. Others may bring forward purchases from next month. Counting every promotional sale as incremental overstates the gain.
Define the comparison period and who receives the offer. Watch later purchases as well as the immediate campaign. If only new buyers receive the discount, model the full-price and discounted groups separately; the simple all-sales threshold above is no longer the complete calculation.
Include promotion and cost changes
Advertising, payment fees, refunds and additional participant support can change the economics. If the campaign has an extra $600 fixed cost and the objective is to preserve contribution after that campaign cost, required seats become ($6,000 + $600) / $57 = 115.789…, or 116 whole seats.
This is still a simplified contribution comparison. Other fixed costs are assumed unchanged, and we have not measured retention or future referrals. A price at or below variable cost does not support the usual positive-contribution preservation formula.
Design a small offer test
Use the price calculator to check the arithmetic. Then document the proposed audience, capacity, measurement window and contribution objective. The experiment guide helps make the comparison explicit.
A discount can be worthwhile. The useful question is which demand, cost and capacity assumptions must hold for the specific offer to work.
Sources and limits
Contribution definitions draw on OpenStax. All workshop prices, costs, response counts and campaign scenarios are original fictional HBW examples. No industry-wide discount response is assumed.