CSI: Customer Satisfaction Index - what is it and why is it important?

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What is the Customer Satisfaction Index (CSI)?

The Customer Satisfaction Index (CSI) is a rating that measures customer satisfaction with various aspects of a company's operations. This includes an analysis of product quality, service, pricing, staff competence and service efficiency. In order to determine the CSI, surveys are usually carried out in which customers express their impressions of their interaction with the company through a series of specific questions. The data obtained is analysed to produce a final index that reflects overall customer satisfaction.

Why use the CSI?

Using the Customer Satisfaction Index (CSI) provides companies with a number of important benefits:

  • Identification of weaknesses: The CSI allows you to identify areas of performance that need improvement.
  • Optimise products and services: analysing customer feedback helps to make adjustments to products or services, improving their quality.
  • Strengthen customer loyalty: Ensuring a high level of satisfaction helps turn customers into repeat customers, which has a positive impact on sales and profits.
  • Attract new customers: recommendations from satisfied customers are an effective way of attracting new audiences.

Advantages and disadvantages of the CSI

The Customer Satisfaction Index (CSI) is an important tool for companies to measure and analyse customer satisfaction. Let's take a closer look at its main advantages and disadvantages.


The difference between the CSI and other indicators is that it allows you to assess not only the customer's attitude to a particular aspect of service, but also to understand how important that aspect is to them compared to others. For example, it helps to understand what is more important to customers: the politeness of call centre agents or the ability to solve some problems at the first attempt.

Thanks to the CSI metric and its measurement methodology, it is possible to conduct a comparative analysis with competitors and obtain an assessment of your services through the prism of customers' opinions of several companies.

CSI helps identify the service attributes that are most important to customers and have the greatest impact on customer satisfaction. This is particularly useful when overall satisfaction scores, such as NPS, are falling and there is a need to prioritise areas for improvement.

CSI provides the ability to analyse the satisfaction levels of different segments of the target audience, helping to tailor a product or service more effectively to the needs of the majority of that audience.


In the context of NPS, the use of the CSI index requires additional effort in data preparation and analysis. It can be more difficult for customers to complete questionnaires, so the company needs to find effective ways to motivate them to increase their participation, including various methods to stimulate engagement.

How the CSI is calculated

The development of the CSI Index begins with a detailed preparation phase. First, you need to identify the aspects that will be assessed to determine the level of customer satisfaction. There are no strict rules for choosing these parameters, but you can use the criteria adapted to the specificities of your company as a guide:

  1. Product - assess the quality, range and innovation of the goods or services.
  2. Price - perception of pricing policy, price and quality compliance.
  3. Location - convenience of location, accessibility of goods or services.
  4. Promotion - effectiveness of advertising and marketing campaigns.
  5. People - level of service, competence and attitude of staff.

Next, you should break down your business into its key components and formulate appropriate questions for each selected parameter, e.g. how satisfied are you with the service, the price, the conditions in the company's office, if relevant to your situation.

Once the criteria have been identified, a two-part questionnaire is developed: the first part is designed to determine the importance of each criterion to the customer, using a rating scale from 1 to 10 (or another scale if the methodology requires it). The second part of the questions is designed to assess the level of satisfaction with these aspects, usually using the same scale.

The calculation of the Customer Satisfaction Index (CSI) involves collecting feedback from customers, usually through a telephone survey or online questionnaires. This gives you up-to-date information about how customers feel about their interaction with the company. It is best to conduct such a survey shortly after the customer has interacted with the company or received the service requested, to ensure the accuracy and relevance of the data obtained.


The Customer Satisfaction Index (CSI) is an important tool for measuring and improving customer satisfaction. When used correctly, this metric can be instrumental in optimising a company's products and services, strengthening customer loyalty and ultimately driving revenue growth. However, to have an effective impact on business results, CSI must be integrated with other key performance indicators and management strategies to provide a deep and comprehensive understanding of customer needs.