A promotion is profitable only if margin from genuinely incremental units offsets the discount on sales that would ha…
A promotion is profitable only if margin from genuinely incremental units offsets the discount on sales that would have occurred anyway, forward buying, cannibalisation and execution costs. Observed uplift during the event is insufficient: build the counterfactual volume and monitor the post-promotion period.
Decision.
Launch, reduce or cancel a promotion according to break-even uplift and the truly incremental share after timing effects. Estimate no-promotion volume over the same distribution scope and season, correcting for seasonality, trend, competition and calendar, and publish uncertainty around that baseline rather than a single point. Calculate the threshold from baseline contribution divided by promotional unit margin, then add media, placement, coupons, logistics and retailer funding. Separate new buyers, extra frequency, transfer, stockpiling and forward purchases; follow full-price return, repeat purchase and cohort margin.
Worked example.
Price drops from €100 to €80, variable cost stays €55, and baseline volume is 1,000 units. Baseline contribution is €45,000. Promotional margin is €25: €45,000 ÷ €25 = 1,800 units, or +80%, to match contribution. At 1,650 units (+65%), contribution is only €41,250 before media cost and forward buying: a €3,750 loss. Refuse or make the operation shallower when expected uplift is below 80%.
Checks and limits.
Use a comparable seasonal baseline, include all operation-specific costs, correct volume for forward buying and cannibalisation, and track full-price return and repeat purchase. A promotion may nevertheless serve clearance or recruitment goals; counterfactuals weaken during supply or distribution changes, while reference-price and promotional-expectation effects need several cycles to observe.
Resources and sources.
Download the promotional break-even model. Related: simulate price, volume and contribution, control the reference price, measure incremental volume. Sources: Gupta (1988); Bell, Chiang & Padmanabhan (1999); Blattberg & Neslin (1990).