Example data table
| Month | Start Customers | Lost | Gained | End Customers | Customer Churn (avg) |
|---|---|---|---|---|---|
| January | 1,000 | 40 | 30 | 990 | 4.04% |
| February | 990 | 35 | 45 | 1,000 | 3.53% |
| March | 1,000 | 55 | 25 | 970 | 5.59% |
Customer churn (avg) uses: lost ÷ average customers.
Formula used
- Ending customers = Start − Lost + Gained
- Average customers = (Start + End) ÷ 2
- Customer churn rate = Lost ÷ Denominator × 100
- Customer retention = 100 − Customer churn
- Net customer churn = (Lost − Gained) ÷ Start × 100
- Gross revenue churn = MRR lost ÷ Starting MRR × 100
- Net revenue churn = (MRR lost − Expansion MRR) ÷ Starting MRR × 100
- NRR = (Starting MRR − MRR lost + Expansion MRR) ÷ Starting MRR × 100
How to use this calculator
- Enter a month label so you can compare later.
- Fill starting customers, lost customers, and gained customers.
- Leave ending customers blank to auto-calculate it.
- Choose a denominator: average customers is usually smoother.
- Optionally add MRR inputs to calculate revenue churn and NRR.
- Press Calculate to see results above the form.
- Use the CSV or PDF buttons to download your report.
FAQs
1) What does monthly churn rate measure?
It measures the percentage of customers or revenue you lose during a month. It helps you spot retention problems, compare months, and evaluate whether acquisition offsets losses.
2) Should I use starting or average customers?
Average customers is often preferred because it reduces distortion when you grow or shrink quickly. Starting customers is simpler and is common in basic reporting.
3) What is net customer churn?
Net customer churn accounts for gains too. It uses (lost − gained) relative to starting customers. Negative net churn means growth outweighs churn in that month.
4) How is revenue churn different from customer churn?
Customer churn counts accounts lost. Revenue churn focuses on lost recurring revenue, which can rise even with fewer churned accounts if higher-paying customers leave.
5) What is NRR and why does it matter?
Net revenue retention shows how revenue from existing customers changes after losses and expansion. Values above 100% indicate expansions exceed churned revenue.
6) Why does my churn look high with small customer bases?
When the customer count is small, each lost account changes the percentage sharply. Consider using average denominator, tracking rolling averages, and segmenting churn by cohort.
7) Can I use this for subscription and non-subscription businesses?
Yes. For subscriptions, churn often uses customers or MRR. For non-subscription, treat “customers lost” as inactive or non-returning accounts based on your monthly definition.