Most contact centers report on the same handful of numbers: average handle time, cost per contact, calls per agent per hour. These are efficiency metrics. They tell you how cheaply you're running the operation today. None of them tell you which customers are about to leave.
The Metric That Actually Predicts Churn
Customer Effort Score (CES) measures how much work a customer had to do to get their issue resolved - how many transfers, how many repeat explanations, how long the wait. According to research originally developed by Gartner (then CEB), 96% of customers who experience a high-effort service interaction become more disloyal afterward, compared to just 9% of customers with low-effort experiences. That's an 87-point gap from a single interaction.
Zendesk's CX Trends 2025 report, drawing on data from over 100,000 companies, found that organizations in the top quartile for CES had 22% lower annual churn rates than industry averages. Their modeling also found that a single one-point improvement in CES (on a 7-point scale) corresponded to a 10-15% increase in customer lifetime value.
What High Effort Actually Costs
The damage isn't limited to churn. HubSpot's 2025 Service Hub Benchmark Report found that customers who rate their interactions as low-effort are 3x more likely to refer others and 2.4x more likely to increase their spending, compared to customers who rate interactions as high-effort. On the cost side, Gartner's service operations benchmarking found that high-effort interactions requiring repeat contact or escalation inflate the cost per resolution by 40-60% versus a single-contact resolution.
In other words: the interactions that cost the most to run are the same ones most likely to cost you the customer.
How to Start Tracking It
- Add a one-question CES survey at ticket or call close - "How easy was it to get your issue resolved?" on a 1-7 scale
- Tag repeat-contact reasons so you can see which issues are driving high-effort interactions
- Correlate CES scores against actual renewal and churn data, not just satisfaction scores, to see if the relationship holds in your own book of business
The Takeaway
Cost-per-contact tells you how efficient your contact center is today. Customer Effort Score tells you who's likely to leave next quarter. If you're only tracking the first one, you're managing the budget and missing the warning signs.
