Website key performance indicators(KPIs) are measurable metrics that track progress toward specific website performance goals.
If you were to run a marathon without mile-markers or a finish line, there would be no way to track your progress or determine when you succeeded. KPIs act as mile-markers for website performance and highlight how close you are to achieving your objectives.
This article explores top KPIs to track and best practices in analyzing and optimizing them.
Summary of website key performance indicators
| Concept | Description |
|---|---|
| What are website KPIs? | Website KPIs are quantifiable metrics that help you measure a website's performance with respect to business goals. |
| Server response time | The time it takes for the user to receive a response from the server after sending an HTTP request. |
| Error rate | Percentage of response errors |
| Request size | The data volume the client sends to the server in one HTTP request. |
| Request count | The number of times your website requests external APIs over a specific period. |
| Cache hit rate | The percentage of requests served directly from the cache. |
| Page load time | The time it takes for a webpage to load and become interactive in a user's browser fully. |
| Exit rate | Percentage of sessions that conclude on a specific web page. |
| FCP | The time it takes to render the first DOM content. |
| TTI | The time it takes for a web page to become fully interactive after a user loads it. |
| Average time on page | The average duration users spend actively engaging with the page. |
| Conversion rate | Percentage of website visitors who complete a desired action. |
| Bounce rate | Percentage of users who visit your website and leave without engaging with the page. |
| Page views | Total number of times a web page is viewed or loaded |
| Average session duration | The average time users spend on your website in a single session. |
| Unique visitors | The number of individuals visiting your website. |
What are website key performance indicators?
Website key performance indicators are actionable and quantifiable metrics that measure website performance against specific goals. They allow you to assess how effectively your site serves its purpose and clearly define success. For example, the speed at which a page loads in the browser significantly impacts user engagement and retention. Website developers can analyze a metric like page load time and determine if immediate optimization is needed.
Website KPIs help you to:
- Gain a detailed perspective on user experience and the challenges they experience while navigating through your website.
- Identify areas where your website is underperforming.
- Assess the effectiveness of your SEO strategies and identify which keywords and content are driving traffic to your site.
Request-level vs. page-level KPIs
Website KPIs can be grouped into two categories based on focus and granularity of measurement: request-level and page-level metrics.
Request-level metrics assess the speed and efficiency of individual server requests. Page-level metrics, on the other hand, offer a comprehensive view of the performance of the entire web page, including the collective behavior of multiple requests. We have summarized the difference below.
| Description | Request-level metrics | Page-level metrics |
|---|---|---|
| Granularity | Provide detailed information on the performance of each request. | Provide a broader view of the overall page performance. |
| Usage |
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| Optimization |
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Top 5 request-level website KPIs
Server response time
Server response time is the time it takes for the user to receive a response from the server after sending an HTTP request. It is the time between when the user requests something from a website and when the user starts getting the data.Imagine you order a meal from a restaurant. Server response time is the time it takes from when you place your order to when the waiter brings the food. The faster the waiter brings your meal, the better your dining experience.
Tracking this metric helps identify server-related issues, such as slow processing or bottlenecks during peak load. It allows for timely optimizations to improve overall user satisfaction and website performance.
Error rate
Errors cause frustration and hinder functionality. Error rate measures the percentage of requests that result in errors. A high error rate suggests underlying server, application, or network infrastructure issues. You can identify and address technical problems proactively to ensure reliable website performance.
Request size
Request size is the data volume the client sends to the server in one HTTP request. It includes the request headers, payload, and any query parameters.
Large requests consume significant network bandwidth and can sometimes strain the server, leading to slower response time. Monitoring and identifying patterns in request size optimize data transfer and compression.
Request count
Request count tracks how often your website requests external APIs over a specific period. It helps you understand how often your system asks for data or services from other sources.
Request count also gives you an insight into how much your system relies on external APIs. A high request count can indicate heavy usage, which might slow down your system or lead to higher costs.
Cache hit rate
Caching improves response times and lessens the strain on your servers. Cache hit rate refers to the percentage of requests served directly from the cache rather than requiring a fetch directly from the server. The metric indicates how well your application interacts with a content delivery network (CDN) or other caching mechanism.
A low cache hit rate could indicate that your cache is ineffective in storing or retrieving data. This results in slower performance and more server stress.
Top 5 page-level website KPIs
Page load time
Page load time is the time it takes for a webpage to fully load and become interactive in a user's browser. Generally, faster page load times improve user satisfaction, increase conversion rates, and boost search engine rankings.
Slow page load times can negatively impact user experience and increase bounce rates, but they don't always indicate poor page performance. Sometimes, users are willing to wait for high-value content or products. For example, an e-commerce site might experience slower page load times during peak shopping hours or flash sales. However, this situation only partially represents the typical website experience.
Exit rate
Exit rate is the percentage of sessions that conclude on a specific web page, reflecting how often users leave your website from that page. It gives insight into which page(s) fail to provide the necessary next steps to keep users engaged. You can identify content or design improvements to retain user attention and encourage further website exploration.
First Contentful Paint (FCP)
First Contentful Paint (FCP) is a performance metric that measures the time it takes to render the first DOM content, such as text, images, or graphics, when a user visits a webpage. For instance, on a news website, FCP measures the time it takes for the headline and the first paragraph to appear.
A low FCP score means users quickly see meaningful content, enhancing their perception of site speed. Conversely, a high FCP score makes the site feel slow. For a better experience, aim for an FCP score of about 0 - 1.8 seconds. You can read more about FCP here.
Time to Interactive
Time to Interactive (TTI) is a website performance metric that measures how long it takes for a web page to become fully interactive after a user loads it. For example, for an online shopping website, TTI is the time it takes for elements like product filters, add-to-cart buttons, and other interactive features to become responsive.
A lower TTI score of under 3.8 seconds means users can engage with the page faster, potentially lowering bounce rates. Improving TTI increases user retention and positively impacts SEO rankings.
Average time spent on page
Average time on page measures the average duration users spend actively engaging with the page. It provides insights into user engagement and content quality. It is calculated by dividing the total time spent on the page by all users by the total number of page views, excluding the last page of a session due to the lack of a subsequent page view to accurately measure duration. A good average time on a page is 1 minute 30 seconds.
More KPIs related to business goals
Conversion rate
Conversion rate measures the percentage of website visitors who complete a desired action, such as purchasing, filling out a form, or signing up for a newsletter. For example, if your website receives 500 visitors and 50 make a purchase, the conversion rate is 10%.An increase in conversion rate indicates that your website and marketing efforts effectively turn visitors into customers or leads.
Page load time has a significant impact on conversion. Slow-loading pages can deter visitors from completing actions. Even a one-second delay in page load time can significantly reduce conversions. For instance, Amazon saw a 1% revenue increase for every 100-millisecond improvement in page load time.
Bounce rate
Bounce rate refers to the percentage of users who visit your website and leave without interacting further on the website. An increase in bounce rate doesn't always indicate a poor user experience. While it can signal issues like slow page load times or unengaging content, it can also mean visitors quickly find what they need.
Page views
Page views refer to the number of times a web page is viewed or loaded. If your web page is accessed 400 times a week, each visit—whether by the same or different users—adds to your page view count.
In business and marketing, high pageview counts signify audience engagement and content relevance. Conversely, decreasing page views indicates a need to refine content or increase marketing efforts to re-engage the target audience. Websites with well-optimized content often have a higher average page view count, which contributes to better user engagement and overall performance.
Average session duration
Average session duration measures the average time users spend on your website in a single session. A longer average session duration shows that users are more interested and involved—for example, exploring product pages, reading blog posts, or watching videos.
Slow server responses may frustrate users, leading them to leave sooner, which can shorten session duration and signal potential issues with website performance.
Unique visitors
Unique visitors represent the number of individuals visiting your website within a specified time frame. Each unique visitor is counted only once, regardless of how often they return. For example, if a user visits your site thrice a month, they are only counted once in your monthly metric.
It helps you understand the actual number of people engaging with your content. You can assess your website’s reach and effectiveness in attracting new audiences. It is often a measure of marketing success.
Monitoring and analyzing website KPIs
Implement continuous monitoring
Website KPIs are living, breathing metrics. As your business grows, it should be monitored and modified regularly. What worked six months ago might not be as effective today. Stay flexible and inquisitive, always seeking new ways to measure success.
A continuous performance monitoring process also helps you observe trends and patterns over time. This information allows you to adjust your approach as needed and drive continuous improvement.
Use automated monitoring tools
The right tools make measuring and acting upon your website's key performance indicators easier.
WebPageTest is a powerful web performance optimization tool with free tier access that gives you detailed reports and an at-a-glance summary of several page-level metrics. You can run performance tests for your site and access historical data to monitor progress. You also get an optimization checklist that covers image compression, CDN, caching, and more.
The pro version of the tool lets you visualize the impact of changes directly within the tool. For example, you can test the impact on KPIs if you write a new script or modify an image without making any changes to your site. The tool also makes proactive suggestions so you can make systematic changes to your website for maximum impact.
However, tools like WebPageTest only tell part of the story. It’s equally important to monitor the website in real time using real-user monitoring (RUM) and synthetic monitoring tools.
Real-user monitoring metrics are gathered from the browser of the end-users. In contrast, synthetic monitoring is simulated from hundreds of points across dozens of service providers worldwide to provide a perspective on how your website responds to global users. Read this article which explains RUM and synthetic monitoring approaches in more detail.
From a broader perspective, it’s also important to understand how third-party dependencies and core internet systems, known as the Internet Stack, impact your website's performance.
Catchpoint’s IPM tool offers insights into all external services' past and present performance and their interrelationships with internal services. It helps you better understand if a deterioration in user experience on your website is due to domain name service (DNS) delays, content delivery network (CDN) malfunctions, or a delay in traffic routing between internet service providers (ISP). This perspective saves time troubleshooting and avoids misdiagnosing performance issues.
Prioritize and act on critical metrics
Focus on the most critical metrics to avoid information overload. Too much data can lead to analysis paralysis, making it challenging to draw actionable conclusions.
Also, don't overlook qualitative feedback from user surveys, customer support interactions, and other sources. These insights add context to your KPI data, helping you make more informed decisions.
Last thoughts
Businesses build websites for specific purposes, and website key performance indicators help you track how your website’s performance impacts business goals. Knowing which KPIs to track is just the beginning. You must continuously monitor and track values against historical data to identify trends. Optimization includes making client- and server-side changes and addressing network issues slowing down third-party interactions.