A 10% price discount does not necessarily reduce your profit by 10%. If the starting gross margin is modest, the discount can remove a much larger share of gross profit per sale.
Before running a pharmacy promotion, do the unit economics. The examples here concern hypothetical commercial arithmetic—not recommended medicine prices, tax treatment or incentives to supply unnecessary products.
Separate margin from markup
Gross profit per unit is net selling revenue minus the applicable cost of goods sold. Gross margin divides gross profit by selling revenue; markup divides gross profit by cost.
With a selling price of 100 and cost of 80, gross profit is 20. Gross margin is 20%, but markup is 25%. Calling both “25% margin” will overstate the available discount room.
Use a consistent tax basis and cost definition. Your accountant can confirm how discounts, returns and purchase incentives should enter the records.
Calculate the effect of a discount
With the same hypothetical cost of 80, a 10% discount reduces the selling price to 90. Gross profit becomes ten. Gross profit per unit has fallen by 50%, even though the price fell by only 10%.
To preserve the original total gross profit before any other changes, the required sales-volume multiplier is:
Original gross profit per unit ÷ discounted gross profit per unit.
Here the multiplier is 20 ÷ 10 = two. Selling 100 discounted units generates the same gross profit as 50 undiscounted units, before considering additional fulfilment costs.
If discounted gross profit is zero or negative, this multiplier does not produce a workable target. Do not hide a loss-making unit behind a large revenue forecast.
Include the costs that change with the offer
Payment fees, packaging, delivery and extra handling can reduce the contribution from each additional order. Suppose an order contributes 40 after goods cost, then incurs eight in variable fulfilment cost. Contribution is 32. A discount of 15 reduces that to 17, assuming the other inputs stay unchanged.
To maintain the same total contribution, required order volume rises by approximately 32 ÷ 17, or 1.88 times. That is an 88% increase, not a 15% increase. These assumptions should be written beside the calculation.
Do not treat allocated fixed rent as a per-order cash cost that disappears with one fewer sale. Keep fixed overhead and variable contribution distinct.
Design a bounded experiment
Specify the eligible lawful offer, dates, maximum exposure and success measure. Compare gross contribution, refunds, service workload and availability—not revenue alone.
Use an ordinary comparison period with similar trading conditions. A festival week and a quiet week are not equivalent. Treat any measured increase cautiously unless you can distinguish the offer from other changes.
Avoid claims that a promotion proves better patient outcomes or encourages clinically unsuitable purchases. A business experiment should operate within appropriate professional and legal boundaries.
Build the software controls
For developers, record both the undiscounted and final values, who authorised the discount, and which rule applied. Calculate percentage and fixed discounts consistently. Preserve the original values for returns and audit review.
For the owner, a useful weekly check is: which discounts were offered, what contribution remained, and did the intended authorised customers receive the intended terms? Exceptions need an explanation rather than being hidden in the average.
Use RunMyPharmacy's POS workflow to evaluate discount handling and its reporting tools to review sales records. The contribution calculator in this article is a separate worksheet, not a claim of an automated promotion-analysis feature.
Disclosure: written for the RunMyPharmacy team with AI drafting assistance and an editorial check of examples, links and product claims. We build the linked product. Examples are hypothetical; worksheets and illustrative software-design advice are not guarantees of product automation.
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