Comprehensive Guide
Learn more in our Business & Tax Guide.
How it works
Customer retention rate is the percentage of existing customers a business keeps over a period, calculated as the ending customers minus new customers acquired, divided by the customers at the start. Start with 1,200, finish with 1,260 having signed 240 new ones, and retention is 85% — the original base shrank by 180 even while the total grew. Subtracting new arrivals is what makes the metric honest: without it, aggressive acquisition paints a leaking bucket as growth. Retention deserves its reputation as the quietest powerful lever in business economics. Keeping a customer costs a fraction of replacing one, retained customers buy more over time and refer others, and the effect compounds — a base retaining 90% versus 80% diverges dramatically over a few years on identical acquisition. The calculator pairs retention with its mirror, churn, and the raw counts of who stayed and left. Three usage rules keep readings meaningful. Measure over fixed windows and keep the window constant, since the same business shows very different rates monthly versus annually. Remember retention counts surviving customers, not repeat purchases — someone active without reordering still counts as retained here. And on small bases, a handful of departures swings the percentage wildly, so read small-sample months gently.Formula
Retention rate = ((customers at end - new customers) / customers at start) x 100 | churn rate = 100% - retention rate
Tips
- Fix the measurement window — monthly and annual retention tell different stories.
- Acquisition can mask churn: always separate kept customers from new ones.
- Win-backs returning mid-period can push retention over 100%; report them separately.
- Small customer bases swing wildly — judge trends, not single-month percentages.
- Pair retention with lifetime value; the two multiply into your marketing ceiling.