Find the revenue you may already be missing

Three sources of aftermarket demand

Replenishment demand comes from products that wear out or get consumed: filters, bags, belts, cartridges, blades, seals and chemicals. Compatibility demand comes from shoppers who need to know precisely which of several parts fit an existing machine. Upgrade demand comes from accessories that improve the performance or usefulness of the equipment already owned.

A merchant may operate in all three markets. Do not mix them into one forecast: they have different purchase cycles, risk of incorrect fitment, and reasons to buy. A coffee-machine gasket and a premium grinder accessory should not be modeled as the same type of opportunity.

Estimate the opportunity with an explicit model

Start with the installed base: the number of relevant units your store has sold and that are likely still in use. Estimate demand per active unit, the share of those purchases you currently capture, gross margin per order and the cost of winning incremental orders.

Illustration: suppose 1,000 active machines each create 1.5 eligible replacement purchases per year at an average selling price of $35. The modeled category demand is 1,500 purchases, or $52,500 in annual gross merchandise value. If you capture 20% today, current captured revenue is $10,500. Moving to 30% would add $5,250 in annual revenue before returns, promotions, shipping, acquisition costs and margin effects. The 30% result is a scenario, not a forecast.

Useful formula: incremental gross profit = active units × annual eligible purchases per unit × change in capture rate × average order value × contribution-margin rate − incremental program costs. Use contribution margin after variable costs, not revenue, when evaluating whether to invest.

Validate demand before automating

• Export orders for one meaningful equipment family and its replacement SKUs; identify repeat purchases without assuming all customers own the same product.
• Check support tickets and on-site searches for model numbers, 'does this fit?', filter names and requests for manuals.
• Inspect 20 high-volume equipment product pages and count how often the correct replacement is linked and purchasable.
• Ask five merchants, customer-service agents or repeat customers how the right replacement is currently found.
• Record product availability and margin: promoting an out-of-stock or unprofitable part is not a win.

Decision rule

Choose a first category only if customers have a recurring or accessory need, the correct products can be verified, and the incremental contribution margin is worth the work. If any of these conditions fails, pick a different category rather than scaling the same idea.