Subscription Revenue Calculator

Month-t net revenue for a cohort is N₀ × (1 − c)^t × P × (1 − k), where N₀ is starting subscribers, c monthly churn, P price, and k the commission rate. Summing the geometric series gives cohort lifetime revenue = N₀ × P × (1 − k) ÷ c — a clean closed form that shows churn in the denominator doing the real damage. Halving churn exactly doubles lifetime revenue; halving commission (30% to 15%) raises it by only 21%.

For a whole business rather than one cohort, layer cohorts: each month’s new subscribers start their own decay curve, and total MRR is the sum of all surviving cohorts. Steady acquisition against constant churn converges to an equilibrium base of (new subscribers per month) ÷ churn — acquire 200 per month at 8% churn and your base plateaus at 2,500 subscribers no matter how long you run, which is the single most sobering output of this model.

Three refinements separate a toy model from a useful one. First, churn is not constant: first-renewal churn (often 20–40% for monthly plans, including trial-to-paid failures if you count trials) far exceeds the 3–8% of mature subscribers, so a single blended rate flatters early months and understates the long tail. If you have cohort data, use month-1 churn and a mature churn separately. Second, use the right commission per revenue slice — year-two-plus subscribers cost you 15%, not 30%.

Third, mind the plan mix. Annual plans book revenue upfront and churn annually, so mixing them into a monthly model at face value distorts both revenue timing and effective churn; convert annual subscribers to monthly-equivalent revenue (price ÷ 12) with their monthly-equivalent churn (1 − (1 − annual churn)^(1/12)) before summing. Done properly, the projection becomes the direct input to LTV and to your maximum acquisition spend.