Fictional inputs
Illustrative product economics
| Input |
Value |
| Regular selling price, before sales tax |
$50 |
| Product cost per unit |
$30 |
| Promotion discount |
10% |
| Baseline units in comparison period |
100 |
Calculation
Regular gross profit: 100 × ($50 − $30) = $2,000. Promotional price: $50 × 90% = $45. At $15 gross profit per unit, matching $2,000 requires 133⅓ units, or at least 134 whole units. That is a 33⅓% theoretical increase, rounded up to 34% for whole units.
What could change the answer?
A vendor allowance could reduce product cost. Customers could buy other products, shift a purchase they would have made anyway, or return later. Clearing aging stock could be worthwhile even at lower gross profit. The two periods might not be comparable.
Evidence to check
Product invoices, allowances and credits; item-level sales and discount records; comparable trading periods; whole-basket gross profit; stock availability; and repeat-purchase information where lawfully available. An allowance is not assumed until supported.
Proposed test
The store manager and finance lead could first review one completed promotion against an agreed comparable period. Confirm costs and discounts, compare gross profit across the whole basket and record competing explanations before changing prices.
Stop/go rule
In this simplified example, 120 discounted units produce $1,800 gross profit—$200 below the baseline. That alone does not support expanding the promotion. At 134 units, gross profit is $2,010, only $10 above baseline before any added cost. Treat that as insufficient proof of a worthwhile change if measurement uncertainty or extra costs exceed $10.
A result that supports no change
If a documented $5-per-unit vendor allowance applies to every discounted unit, net product cost falls to $25 and gross profit returns to $20 per unit. At 100 units, the simplified gross profit matches the baseline. Do not recommend removing that promotion merely because a discount appears in the POS.
Effort and limits
Illustrative validation budget: one manager hour and one finance hour to locate and check records, plus a 30-minute joint review. Actual effort must be agreed. No savings, annual benefit, audit payback or cash available for debt service is established by this example.