A 10% price cut can require far more than a 10% increase in sales to leave a business with the same contribution toward its overheads and profit. The answer depends on what the business earns on each sale after costs that rise with volume.
Discounts can attract customers, clear stock or bring forward purchases. They can also reduce the money available to pay rent, salaries and other costs that do not disappear when a product is discounted. Before announcing a promotion, it helps to calculate how many extra units are needed to cover the reduction.
Start with contribution per sale
Contribution per unit is the selling price minus the costs that change with each unit sold. Those costs might include the product, packaging, payment processing and delivery. The remainder contributes to fixed costs and, after those are covered, profit.
Consider a hypothetical item sold for $100 with $60 in variable costs. It contributes $40 per unit. If the price falls to $90 and variable costs stay at $60, its contribution falls to $30. The selling price has dropped 10%, but contribution per unit has dropped 25%.
To generate the same total contribution as 100 full-price sales, the business needs 134 discounted sales, rounding up from 133.33. That is 34 more sales, assuming every unit sold in the comparison is discounted and the cost per unit stays constant. This is a contribution comparison, not a calculation of net profit.
The US Small Business Administration explains break-even analysis as a way to compare fixed costs, selling price and variable costs. Our guide to fixed costs explains why some expenses remain even when sales slow.
Count sales that would have happened anyway
A promotion does not necessarily create every purchase made during the offer. Some customers would have paid full price, while others may have bought the same item the following week. If the business offers a reduction to all customers, it gives up contribution on those purchases too.
A simple comparison with the previous week can mislead. Payday, the weather, advertising and holidays may all affect demand. A business with enough customers might compare similar groups, one receiving the offer and one not, while protecting customer data and checking that the comparison is fair. Smaller businesses can still record the period, audience and products involved, then repeat a test before drawing strong conclusions.
The goal is to estimate additional contribution after promotional costs. A campaign that produces more orders can still leave less money for overheads if the average contribution falls sufficiently.
Include costs outside the product
Delivery subsidies, payment fees, paid advertising, returns and extra customer service can all change the result. Some vary with the number of orders; others, such as a fixed campaign fee, are incurred whether or not a customer buys.
Recalculate if the supplier offers a volume discount or if a large order triggers overtime. The $60 example will not remain valid if the promotion changes fulfillment costs. Also check whether stock sold at a discount prevents a later full-price sale.
Businesses with several products should look at the whole basket. A discounted item may attract customers who buy other products, but additional items should be counted only where there is reasonable evidence the promotion contributed to those sales.
Decide what the promotion is for
Matching the previous contribution is only one possible objective. A retailer might accept a lower return to clear products that are nearing expiry. A new business might choose to spend money acquiring customers, provided it has a realistic budget and does not assume every first-time buyer will return.
Set a limit in advance: the dates, products, eligibility, maximum spend and the result that would justify repeating the offer. Then compare actual contribution, returns and repeat purchases with the assumptions. A larger sales total is worth investigating, but it is not enough on its own to show that a discount paid for itself.
