Churn Rate

Churn rate is the percentage of customers (or subscribers, users, or revenue) that are lost within a defined time period.

Formula:

Churn Rate = (Customers Lost in Period ÷ Customers at Start of Period) × 100

Example: 500 customers at start of month, 25 cancel → 5% monthly churn rate

Churn is the primary retention metric for subscription businesses. It directly determines Customer Lifetime Value — because a customer’s value is the product of what they pay and how long they stay.

Types of Churn

Type	Measures	Formula
Customer churn	% of customers lost	Lost customers ÷ Starting customers
Revenue churn (MRR churn)	% of MRR lost from cancellations	Lost MRR from cancellations ÷ Starting MRR
Net revenue churn	MRR lost minus expansion revenue	(Lost MRR − Expansion MRR) ÷ Starting MRR
Voluntary churn	Active cancellations by customer	Tracked via cancellation surveys
Involuntary churn	Failed payments, expired cards	Tracked via payment failure data

Net revenue retention (NRR) > 100% means existing customers are collectively spending more each period than you’re losing — the hallmark of a healthy SaaS expansion model.

Churn’s Impact on LTV and Unit Economics

Churn is the primary driver of LTV:

LTV (simplified) = Average Monthly Revenue per Customer ÷ Monthly Churn Rate

Monthly Churn	LTV (€50/mo ARPU)
10%	€500
5%	€1,000
2%	€2,500
1%	€5,000
0.5%	€10,000

Halving churn doubles LTV — with no change in pricing or new customer acquisition. This makes churn reduction one of the highest-ROI activities in a subscription business.

Churn and the CAC:LTV Ratio

At 10% monthly churn, LTV is €500. If CAC is €400, the ratio is 1.25:1 — barely profitable, with no margin for product, support, or ops costs.

At 2% monthly churn, LTV is €2,500. Same CAC = 6.25:1 ratio — a healthy, scalable business.

The path to a fundable unit economics story is often churn reduction, not new customer acquisition.

What Causes Churn

Product-related:

• Poor onboarding — customers never reach the “aha moment”
• Lack of perceived value — they don’t use it enough to justify the cost
• Missing features that prompted signup

Service-related:

• Poor customer support responsiveness
• Unresolved technical issues

External:

• Budget cuts
• Company downsizing
• Competitor switching

Involuntary:

• Failed credit card payments (typically 20–40% of total churn)
• Account expiry without notification

Reducing Churn: The CRO Connection

Churn reduction is the post-acquisition CRO problem. The same research-and-optimization methodology that improves signup conversion applies to improving activation and retention:

1. Identify the churn point — when in the customer lifecycle does churn peak?
2. Research why — exit surveys, cancellation interviews, usage data analysis
3. Form hypotheses — what changes to onboarding, engagement, or product would address root causes?
4. Test and implement — run experiments on onboarding sequences, in-app triggers, success check-ins

For voluntary churn specifically, exit survey data is the most actionable source. One question — “What was the primary reason you’re cancelling?” — with 5–6 structured options plus free text, typically reveals patterns within 30–50 responses.