Is revenue from existing customers growing or shrinking?

Why net revenue retention separates growing businesses from dying ones

A business with 110% net revenue retention could stop acquiring new customers entirely and still grow 10% per year. A business with 85% NRR needs to replace 15% of its revenue every year just to stay flat, before it can even think about growing.

This is why some businesses feel like they're running hard and going nowhere. They're adding new customers at the top while existing customers are spending less or leaving at the bottom. The net effect is a treadmill.

If your existing customers are spending more each month (upsells, larger orders, expanded services), you have a compounding asset. If they're spending less, you have a compounding liability.

Net revenue retention: the formula and what it reveals

Net revenue retention (NRR) measures how much revenue your existing customer base generates compared to the prior period:

An NRR of 100% means your existing base is spending exactly the same. Above 100% means expansion (customers are buying more). Below 100% means contraction (customers are buying less or leaving).

Top-performing SaaS companies often have NRR above 120%. For service businesses, anything above 95% is solid. Below 85% is a warning sign.

How to measure existing customer revenue in QuickBooks Online

1. 1
   Go to Reports → Sales by Customer Summary

   Set the date range to last month. Export to CSV. This gives you each customer and their revenue for last month.

2. 2
   Run the same report for this month

   Change to the current month. Export to CSV.

3. 3
   Match customers across both spreadsheets

   Use VLOOKUP to match customers by name. For each customer who appears in both months, pull their revenue from each period into side-by-side columns.

4. 4
   Exclude new customers from this month

   Remove any customer who appears in this month's report but not in last month's. You only want the returning base.

5. 5
   Sum and compare

   Sum last month's revenue for returning customers. Sum this month's revenue for those same customers (including $0 for those who churned). Divide this month by last month and multiply by 100. That's your NRR.

How to measure existing customer revenue in Xero

1. 1
   Go to Business → Invoices for each month

   Export invoices for last month and this month separately. In each spreadsheet, create a pivot table or use SUMIF to total revenue by customer.

2. 2
   Match and compare the two customer-level summaries

   Same process as QuickBooks: match by customer name, exclude new-to-this-month customers, and sum the revenue for the returning cohort in both periods.

3. 3
   Calculate NRR

   This month's returning customer revenue / last month's same-customer revenue x 100.

What it takes to track net revenue retention monthly

• 30-45 minutes of spreadsheet work each month. This is one of the most labor-intensive retention metrics to calculate manually.
• Customer name matching can be messy.If “Riverside Dental” appears as “Riverside Dental LLC” in one month, your VLOOKUP misses it. Small data quality issues can skew the result.
• The number alone does not tell you where to act. An NRR of 88% tells you the base is contracting. But is it because one large client reduced their spend, or because many small clients are leaving? You need the breakdown.

Or track existing customer revenue automatically

Bottomline calculates net revenue retention every month by matching customer identities across periods and comparing their spend. You see the overall number plus the breakdown: who expanded, who contracted, and who left.

Instead of a single percentage, you get the full picture: which customers grew, which shrank, and which left. That tells you not just the size of the problem, but where to direct your energy.