How much is churn costing you?

Free lost MRR and lifetime value calculator · Last updated November 2026

Put in three numbers and see what churn takes from the customers you already have: this month, over the next year, and in what each customer is worth. Nothing you enter leaves your browser.

Paying customers Average revenue per customer ($/month) Monthly churn rate (%) Gross margin (%)

MRR lost this month

$800

MRR gone after 12 months

$7,746

Revenue lost over 12 months

$54,099

Lifetime value per customer

$2,000

Cutting churn by one point, to 3%, would lift lifetime value to $2,667 and keep $14,060 of revenue over the year.

Where do these numbers come from?

MRR lost this month is customers times price times churn rate. Everything after that compounds, because each month's churn comes out of a smaller base. After 12 months the MRR left is your MRR times (1 minus churn) to the power of 12.

Revenue lost over 12 months adds up the gap between what you would have billed with no churn and what you actually bill, month by month. With the defaults, 200 customers at $100 and 4% churn lose $800 of MRR this month, about $7,700 of MRR by month 12, and about $54,000 of revenue across the year.

Lifetime value is price times gross margin divided by churn. One over the churn rate is the average customer lifetime in months, so 4% churn means about 25 months.

Churn sits underneath LTV, so a one-point cut from 4% to 3% raises what every customer is worth by a third.

It leaves out new sales and expansion on purpose. Those offset churn, but they don't make it cheaper.

Which calculator do you need next?

Don't know your churn rate yet? Work it out with the churn rate calculator.
Want LTV with expansion and discounting? Use the LTV calculator.
Want new sales in the model too? The MRR simulator projects 12 months of growth against churn.
Ready to cut it? The Health Check scores your retention setup and tells you what to fix first, and the guide to reducing SaaS churn ranks the tactics by evidence.

Questions about the cost of churn

Short answers, with the same formulas the calculator uses.

How much is churn costing my SaaS?

Multiply your MRR by your monthly churn rate to get the MRR you lose this month. The bigger cost is what compounds: at 4% monthly churn, a business with $20,000 MRR and no new sales loses about $7,700 of that MRR within a year and about $54,000 of revenue it would otherwise have collected.

How do I calculate lost MRR from churn?

Lost MRR this month is customers times average revenue per customer times monthly churn rate. Over 12 months, the MRR still left is your MRR times (1 minus churn) to the power of 12, so the MRR gone is the difference between that and where you started.

How do I calculate customer lifetime value from churn?

A simple LTV is average monthly revenue per customer times gross margin, divided by monthly churn rate. A customer paying $100 a month at 80% margin with 4% monthly churn is worth about $2,000 in gross profit.

Why does a one-point churn cut change LTV so much?

Because churn sits in the denominator. Going from 4% to 3% monthly churn stretches the average customer lifetime from 25 months to about 33, which lifts LTV by a third without changing price or margin.

Does this calculator include new customers or expansion revenue?

No. It isolates what churn takes from the customers you have today. New sales and upgrades would offset part of it, but they do not change what the churn itself costs. For a model with growth included, use the MRR simulator.

What should I do once I know what churn costs?

Find out which kind of churn it is before spending money on it. Failed payments and cancellations at the cancel button are the fastest to fix. The free Health Check tells you which lever to pull first.