Overview

Track the number of lost customers and understand why they are leaving your brand to increase retention rates.

What is Lost Customers?

Lost customers can have a significant impact on the success of an ecommerce business. By understanding why customers leave, businesses can create strategies to improve loyalty and retention rates. Utilizing the ‘Sum of Lost Customers’ formula, ecommerce analysts can determine the number of customers who have not made a purchase in a given period. This can help inform decisions around customer experience and loyalty strategies to improve customer retention.

Formula

The ‘Sum of Lost Customers’ formula is used to calculate the number of customers who have not made a purchase in a given period. It is a metric for tracking customer churn rate. It is expressed as the number of customers who have not made a purchase in the defined period divided by the total number of customers.

Example

For example, let’s say in a three month period you had 1,000 customers who made an average purchase of $100. During the same period, you had 200 customers who made no purchase. Your ‘Sum of Lost Customers’ would be 200/1,000 or 20%.

Why is Lost Customers important?

Lost customers can have a negative impact on the success of any ecommerce business, as early churn decreases revenue streams dramatically. A customer who churns early does not give the business a chance to drive any future revenue from them. Many companies underestimate the number of lost customers on their platform which can have a long-term financial implication. Utilizing the ‘Sum of Lost Customer’ formula, can help ecommerce businesses get a better understanding of customer churn and determine where their improvement opportunities are.

Which factors impact Lost Customers?

There are several strategies that businesses can implement to improve customer retention and reduce customer turnover. Here are some tips to increase loyalty in customers:

  1. Create an exceptional customer experience: Customers are more likely to stay loyal if they’ve had a good experience with a brand’s product or service. Focus on delivering a personalized customer experience to build trust in your brand.
  2. Use customer feedback: Regularly collect and analyze customer feedback to understand why customers are not sticking around. Identify successful customer retention strategies that work for your customers and replicate them.
  3. Offer loyalty rewards: Offering loyalty rewards is a great way to reward customers for their loyalty and encourage them to stay with your brand. You can offer incentives such as discounts, free shipping, and exclusive access to new products or services.

How can Lost Customers be improved?

Some of the most common factors that influence customer retention include: product quality, customer service, pricing, delivery time, trust, and convenience. Understanding the needs of your customers and their buying behaviors can help you identify areas that need improvement. Improving customer experience, value exchange, and customer service are key to reducing customer churn.

What is Lost Customers’s relationship with other metrics?

Lost customers can have a direct impact on the success of any ecommerce business. It is also important to understand how it affects other ecommerce metrics. It is crucial that ecommerce analysts consider how customer churn can determine the success of other metrics, such as customer satisfaction, average order value, and total revenue. A better understanding of customer churn can help make better decisions when it comes to customer service, value exchange, and product delivery.

Free essential resources for success

  • Your Guide to Modern Measurement thumbnail

    Your Guide to Modern Measurement – the Causal Revolution

    Measure true marketing impact with incrementality, MMM, and causal analytics in a privacy-first world

  • The 2026 Wellness CPG Marketing Playbook thumbnail

    The 2026 Wellness CPG Marketing Playbook

    A Data-Driven Playbook for Measuring Growth and Incrementality in Wellness CPG Brands

  • A Guide To Marketing Effectiveness Measurement For Ecommerce Brands

    A Guide To Marketing Effectiveness Measurement For Ecommerce Brands

    Turn fragmented data into clear insights that improve ecommerce marketing performance.

Discover more from Lifesight

  • Why MTA Is Broken – And Why Unified Measurement Is the Only Way Forward

    Published on: June 15, 2026

    Why MTA Is Broken – And Why Unified Measurement Is the Only Way Forward

    MTA can show what happened before a conversion, but not what actually caused it. Learn why modern marketers are moving toward causal measurement, incrementality, and unified measurement.

  • Causal Marketing Mix Modeling (MMM)_ The Complete 2026 Guide

    Published on: June 8, 2026

    A Complete Guide to Causal Marketing Mix Modeling

    A concise guide to Causal MMM and how it measures true incremental marketing impact using causation over correlation. It explains why modern marketers use it for better budgeting, forecasting, and privacy-safe decision-making.

  • The Future of Measurement Isn’t Another Dashboard

    Published on: June 2, 2026

    The Future of Measurement Isn’t Another Dashboard. It’s a Decision Layer

    Lifesight’s MCP brings trusted causal insights directly into Claude and ChatGPT, where teams plan, optimize, and act.