How a digital marketing agency assesses and measures success

Key performance indicators (KPIs) to measure success

To measure whether the goals are being achieved, digital marketing agencies use key indicators, often called KPIs. (Key Performance Indicators).

These indicators provide a clear picture of how different aspects of the marketing strategy are performing. Here are some of the most important KPIs used:

1. Traffic from search engines

Traffic from search engines, also known as organic traffic, shows how many people find your website through unpaid searches on Google or other search engines. This is an important KPI because it provides insight into how well your website ranks for relevant keywords.

When more people find your website through search engines, they are more likely to become customers. Agencies use tools such as Google Analytics and Google Search Console for to monitor and analyze this traffic.

To increase organic traffic, the agency can implement various SEO strategies. Read more about what SEO is. This may include improving the content on the website, optimizing technical aspects such as website speed, and building links from other relevant websites.

The results of these measures will be measured in terms of increased traffic from search engines, higher rankings for important keywords, and an increase in the number of pages that rank well on Google.

2. Conversion rate

The conversion rate is one of the most critical KPIs in digital marketing. It shows how many of the visitors to the website perform a desired action, such as purchasing a product, filling out a contact form, or signing up for a newsletter. A high conversion rate means that the website effectively converts visitors into customers or potential customers.

the agency can run A/B tests on landing pages. How to analyze the results is covered in our guide to SEO analysis.

The agency can also analyze which parts of the website receive the most attention and which cause visitors to leave the site, and then make the necessary adjustments.

3. Return on investment (ROI)

ROI (Return on Investment) is a KPI that measures how much revenue is generated in relation to marketing costs. ROI is important because it provides a clear picture of how profitable your marketing is. If, for For example, if you spend $10,000 on a marketing campaign and generate $100,000 in sales, your ROI is positive and shows that the campaign has been profitable.

Agencies often use ROI as a key KPI to assess the effectiveness of marketing initiatives. A good ROI means that the marketing budget has been spent wisely and that the strategy is delivering valuable results.

If ROI is low, it may be a sign that the strategy needs to be adjusted, either by optimizing campaigns, reducing costs, or focusing on more profitable target groups.

4. Engagement on social media

Social media engagement is about how many people like, comment, share, and interact with your posts on platforms such as Facebook, Instagram, and LinkedIn.

This KPI is important because it shows how well your content resonates with your target audience. High engagement can also contribute to increased visibility, as posts with a lot of engagement are often prioritized by social media algorithms.

To increase engagement on social media, the agency can work to create more relevant and engaging content.

This may include the use of images and videos, storytelling, and interactive posts such as surveys and competitions.

Engagement is not only measured in the number of likes, but also in how many people comment and share the content, as well as how the target audience reacts to it.

5. Customer retention

Customer retention is a KPI that shows how many customers return to make another purchase. This is an important KPI because it is often cheaper to retain existing customers than to attract new ones.

A high retention rate indicates that customers are satisfied with the product or service and that they are loyal to the brand.

To improve customer retention, the agency can implement various loyalty programs, tailor communication to existing customers, and ensure that customers feel valued.

Regular follow-ups, exclusive discounts, and personalized content can also help keep customers happy and loyal.

6. Cost per enquiry

Cost per enquiry shows what you pay for each new contact from your marketing. The maths is simple: divide the cost by the number of enquiries. Spend $1,000 on ads and get 20 enquiries, and each enquiry costs $50.

This is often the most useful KPI for small and medium businesses. It ties marketing directly to what matters: new customers through the door. If you also know what an average customer is worth, you quickly see whether the marketing pays off.

7. Visibility in AI answers

More and more people ask ChatGPT, Gemini or Google AI Mode instead of scrolling through search results. The agency therefore also has to measure whether your business gets cited in AI answers. This is the newest KPI in the toolbox, and it is measured like this:

• AI traffic in GA4: In May 2026, GA4 got a dedicated channel called AI Assistant. It automatically collects visits from ChatGPT, Gemini, Claude and similar services, with no setup required.
• Know the limits: The channel only catches visits with a recognised source. Clicks from Google AI Overviews count as organic search, and a lot of AI traffic still lands as direct traffic. The numbers are a floor, not a ceiling.
• Search Console: Clicks and impressions from AI Overviews and AI Mode are included in the performance report. If impressions rise while clicks stay flat, you are probably being cited without clicks.
• Manual test questions: Ask your most important customer questions in ChatGPT, Gemini and Google AI Mode every month. Note who gets cited, and watch whether it is you or your competitor.

Want to understand how to get into the AI answers? Read our guide to AEO optimization.

Adaptation of strategy based on results

Once an agency has collected data through KPIs, these figures are used to adjust the strategy. If a campaign is not delivering the desired results, the agency can make changes to improve it.

This often involves testing new ads, changing the target audience, or adapting the website to make it more user-friendly. The agency works continuously to improve results based on what the numbers show.

It is important to understand that digital marketing is an ongoing process. Markets and consumer behavior change, and what worked yesterday may not work tomorrow. Therefore, it is crucial to monitor campaigns in real time and make adjustments when necessary.

This is often referred to as an “agile marketing strategy,” where you can quickly adapt changes to your strategy based on the latest data.

An important part of this process is A/B testing, where different versions of ads, emails, or landing pages are tested against each other to see which one performs best.

For example, a company might test two different versions of an ad on Facebook. One version might have a different title or image than the other. After a period of time, the results are compared to see which ad led to the most clicks or conversions. This approach ensures that the marketing strategy is always optimized for the best possible performance.

Another critical factor is being able to respond quickly to changes in the market or target audience. If an agency discovers that a campaign is not performing as planned, they must be able to adjust the targeting, messaging, or even the budget to ensure that the campaign becomes more effective.

Why is continuous monitoring important?

Digital marketing is not something you just set up and then let run on its own. Continuous monitoring is essential to ensure that campaigns deliver the desired results.

Market trends, consumer behavior, and even technological changes can have a major impact on how a campaign performs. That's why it's important to keep a close eye on all aspects of your marketing so you can make adjustments in a timely manner.

Et professional digital marketing agency will have the tools and knowledge needed to monitor campaigns in real time. This includes tracking KPIs, as described earlier, but also analyzing user data, competitive conditions, and other external factors that may affect campaign results.

For example, an agency might use Google Analytics to monitor traffic patterns on a website, or Insights in Meta Business Suite to analyze engagement on social media.

With continuous monitoring, the agency can quickly identify and respond to issues. If an ad isn't generating enough clicks, the agency can quickly adjust the message, target audience, or budget to improve performance. This approach is crucial to ensuring that marketing efforts deliver maximum return on investment.

How can potential customers evaluate an agency's success?

When considering working with a SEO agency, it is important to look at their previous results. You should ask for examples of how the agency has helped other companies achieve their goals.

Look at client stories and client reviews, and ask for concrete examples from businesses like yours.

The best agencies will be open about the KPIs they use to measure success and how they report these results to their clients. They will also be able to explain why they chose certain strategies and how they adapted these strategies based on the results along the way. This shows that the agency has a thoughtful and data-driven approach to marketing.

In addition, you should consider how the agency communicates with its clients. Regular and clear communication is essential to ensure that you, as a client, are kept up to date on the progress of the campaign and that any concerns are addressed quickly.

A good agency will be a partner that not only delivers results, but also ensures that you understand the process and are comfortable with the decisions that are made.

The price should also match what you get. What is normal to pay is covered in our guide to marketing agency prices.

How we report at Mementor

We believe clients should see the same numbers we do, every day. That is why our SEO and AEO clients get their own dashboard with daily updated data:

• Rankings in both Google and AI search
• Local keyword tracking per city, with Google Business Profile and maps
• Tracking of how your business appears in Google AI answers
• Citation analysis: which AI services cite you, and for what
• Competitor tracking in AI answers, so you see who wins the questions

That way you never have to wait for the monthly report to know whether the work is paying off. Read more about what is included in our SEO packages and AEO packages.

Frequently asked questions

Final words

Measuring success in digital marketing is about more than just looking at numbers. It requires a deep understanding of how different marketing activities contribute to achieving the company's overall goals. Through careful monitoring, flexibility in strategy, and continuous optimization, a digital marketing agency can ensure that your company gets the most out of its marketing budget.

If you are still looking for a partner, read our guide on choosing the right marketing agency.

By understanding which KPIs are most important, how they are monitored, and how strategies are adapted, you as a customer can be confident that your marketing efforts are delivering real results.

This is the key to building a strong digital presence that not only attracts customers but also retains them over time.

Together with a good agency, you can achieve your goals and ensure growth for your business.