Free Trials: Conversion and Contribution

A free trial incurs costs before the business knows which participants will become paying customers. Price the trial population and the paid cohort separately. Dividing the campaign cost only by successful users can be a useful result, but it should not conceal the service provided to everyone who started. Choose a finite paid observation window, define conversion as a completed qualifying payment, and keep later renewals outside the result until they are explicitly modeled.

Cost the whole starting cohort

Suppose 1,000 hypothetical customers start a trial. Each trial costs $2 in incremental service and support, so serving all starters costs $2,000. Acquisition spending is $3,000 and trial setup costs $500. Total trial and acquisition cost is $5,500. If the business already has unused fixed capacity, separate any allocation of that capacity from additional cash payments; the example treats the entered costs as relevant to this campaign comparison.

Follow converted customers into the paid window

Assume 25% of trial starters become paid customers, yielding 250 conversions. Each produces $24 contribution over the selected paid window after the costs of serving paid users and expected refunds, but before the trial and acquisition costs above. Paid contribution totals $6,000. Subtracting $5,500 leaves $500 before any other fixed business overhead. The 25% conversion share is measured against all 1,000 starters, not only users who completed onboarding.

Calculate the required conversion

Covering $5,500 at $24 paid contribution per converted customer requires 229.1667 conversions in expectation. With whole customers and the stated identical outcome, at least 230 conversions are required, equal to 23% of starters. The exact expected-share threshold is approximately 22.9167%. At 170 conversions, paid contribution is $4,080 and the campaign remains short $1,420. Keep that negative result rather than reporting only the customers who eventually paid.

Distinguish several acquisition measures

The $3,000 advertising and acquisition numerator divided by 250 conversions is $12 per paid customer. Including the $2,000 trial service cost and $500 setup increases the full campaign cost per converted customer to $22. Both can be reported if their scope is explicit. Comparing the $12 figure with another offer that includes trial delivery would overstate the apparent advantage. Neither ratio is a guarantee about future customer value.

Inspect the timing and service boundary

Paid contribution may arrive gradually, while acquisition and trial support costs are incurred earlier. Schedule expected collections and payments, including trials that overlap reporting periods. Track whether a trial user receives the same service as a paying user and what additional onboarding is required at conversion. If trial duration changes, adjust service cost and the observation window together rather than assuming the old conversion rate remains valid.

Learn from mature trial cohorts

Compare cohorts at the same age, exclude duplicate identities consistently, and reconcile paid conversions with actual retained payments. A trial registration or saved payment method is not automatically a completed purchase. Test lower conversion, more support demand, and higher refund scenarios. If paid-window contribution is zero or negative, no positive conversion count covers positive trial costs under the unchanged assumptions. All numbers here are hypothetical; the calculation identifies a conditional threshold without promising that the trial will produce it.

Method references: Shopify: customer reports; OpenStax: break-even sensitivity analysis. Accessed October 22, 2026. All dollar figures are hypothetical worked examples.