If you run a Substack, a Patreon, or any subscription product, two numbers matter more than almost anything else: how much recurring revenue you're collecting right now, and how much of it you're quietly losing to cancellations. This calculator turns your subscriber count, average price, and churn rate into monthly recurring revenue (MRR), annual recurring revenue (ARR), and the dollar amount churn is costing you every month — so you can see the leak, not just the growth.
How it works
MRR is the simplest number in subscription business: multiply your paying subscribers by the average price they pay per month. It's not your total lifetime revenue, not a projection, not a goal — it's what your current subscription base generates in a single month if nothing changes. ARR is just MRR annualized, multiplied by 12, giving you the run-rate figure investors, lenders, and your own planning spreadsheet actually want to see.
Churn is where most creators lose track of the real picture. This calculator takes your monthly churn rate as a percent of MRR and converts it into an actual dollar figure — the revenue that walks out the door each month from cancellations and downgrades. That number isn't subtracted from the MRR or ARR shown above (both stay as a snapshot of your current base), but it's the number that tells you how much new revenue you need just to stay flat, before you've grown at all.
Worked example
Say you have 100 paying subscribers at an average of $10/month, with 5% monthly churn.
- MRR: 100 × $10 = $1,000
- ARR: $1,000 × 12 = $12,000
- Revenue lost to churn each month: $1,000 × 5% = $50
That $50 isn't a one-time hit — it recurs every month unless you either reduce churn or add enough new subscribers to outpace it. Over a year, 5% monthly churn compounding against a static subscriber base would erode the majority of that starting $1,000 in MRR if you never replaced a single lost subscriber, which is the entire reason growth-focused creators still obsess over their churn number even while sign-ups are climbing.
How to interpret your result
MRR and ARR tell you where you stand today; the churned-revenue figure tells you how hard you're running just to stand still. A common mistake is celebrating subscriber growth while ignoring that churn is quietly canceling most of it out — if you added 20 subscribers this month but churn cost you the dollar-equivalent of 18 of them, your net progress is closer to 2 subscribers, not 20.
Compare your churned-revenue number against your new MRR from sign-ups in the same period. If churn consistently outpaces new revenue, your subscriber base is shrinking even if the raw subscriber count still looks flat or slightly up (new low-price subscribers can mask fewer high-price cancellations). If new revenue comfortably outpaces churn, your ARR projection is a realistic floor — the true run rate is likely higher once you also account for growth compounding month over month, which a static ARR figure by definition does not.
Also worth checking: is your churn rate revenue-based or subscriber-based? A handful of high-tier subscribers canceling can produce a much bigger dollar hit than raw churn percentage suggests, which is exactly why this calculator asks for a churn rate applied to MRR rather than just a subscriber-count churn — the dollars are what actually pay your bills.
Methodology & sources
The formulas: MRR = subscribers × average monthly price, ARR = MRR × 12, and monthly churned revenue = MRR × (churn rate ÷ 100). All figures round to the cent, and ARR is calculated from the already-rounded MRR so the two numbers stay consistent with each other on the page.
This is standard SaaS and subscription-business terminology, not a proprietary formula — Klipfolio's monthly recurring revenue KPI explainer covers the same MRR definition and why tracking retention alongside growth is essential for any subscription business, whether it's a SaaS product, a newsletter, or a membership community. If your platform reports churn as a percentage of subscribers lost rather than revenue lost, convert it to a revenue-weighted rate first (total MRR lost ÷ starting MRR) before entering it here, since subscriber-count churn and revenue churn can diverge significantly when cancellations skew toward your highest or lowest tiers.