Top Customer Satisfaction KPIs to Power Your Referral Strategy

You don’t need to see numbers to know that a friendly referral is more effective than the most expensive marketing campaigns. It’s word of mouth at its best.  

And a referral strategy can do wonders just because of that. But how should you start your strategy? Should you ask each and every one of your customers for a recommendation? Or is there a way to identify the customers who are more likely to recommend your products to others?  

Which customers are more likely to recommend your products to others? You guessed it, the most satisfied ones. But how can you identify these satisfied customers? 

You’ve come to the right place. Read on and you’ll find out. 

Identifying the right customers for your referral strategy

You don’t need to rely on guesswork to identify the most satisfied customers for your referral strategy. You can track some KPIs to determine your customers’ satisfaction. 

Obviously, the customers who have been with you for the longest time, purchased more frequently from you, engaged the most with your marketing messages, or raved about you online, probably have a high satisfaction level. 

But these are not the only KPIs for customer satisfaction. Below, you’ll find a more comprehensive list of customer satisfaction KPIs that could help you expand the pool of customers you could contact for your referral strategy.  

1. NPS: Identify customers most likely to refer

Net Promoter Score (NPS) helps you understand how your customers feel about your brand. It’s a score based on how likely someone is to recommend your product or service to others, usually on a scale from 0 to 10.

It’s a score based on a single question:

“How likely are you to recommend us to a friend or colleague?”

Respondents are grouped like this:

• Promoters (9–10): Loyal fans who are most likely to refer
• Passives (7–8): Neutral, not likely to promote or complain
• Detractors (0–6): Unhappy and unlikely to refer

The formula to calculate NPS is:
NPS = % of Promoters − % of Detractors

Your referral program will see better results when you involve customers who already want to talk about you. And there’s a reason to act fast. According to Nielsen, 88% of consumers trust referrals from people they know. Promoters are more likely to share while their positive experience is still fresh.

How to use NPS to spot your referral champions

Once you collect NPS responses, your next step is to invite promoters into your referral program. You can do this by connecting your NPS tool (like Delighted, Survicate, or Typeform) with Tapfiliate using Zapier.

Here’s how it works:

• A customer gives you a 9 or 10.
• That score gets picked up by your NPS tool.
• Zapier triggers an action: the customer gets added to Tapfiliate and receives a referral invite automatically.

You don’t need to export a spreadsheet or manually pick out promoters. The whole process runs in the background. While you’re busy writing your morning emails, Tapfiliate is already onboarding new referral partners who are excited about your product.

Once someone joins the program, Tapfiliate tracks their link clicks, conversions, and rewards. You can see which promoters are actively referring and how much value they’re bringing. Below is a snapshot of the Tapfiliate dashboard. 

2. CSAT: Find users who are happy with specific interactions

Customer Satisfaction Score (CSAT) measures how a person feels after a particular interaction, like a support ticket, a product delivery, a live chat conversation, or even a difficult customer situation that has been resolved successfully.

The question is simple:

How satisfied were you with your experience?

Responses are usually scored from 1 to 5 (sometimes 1 to 10). You then calculate the score using this formula:

CSAT = (Number of positive responses ÷ Total responses) × 100

This KPI helps you catch customers at the right moment

Positive responses usually mean 4s and 5s. A high CSAT tells you that something went well at a specific point in the customer journey.

This is useful when you’re running a referral program. Timing matters. If a user just had a great support experience or their first successful result with your product, they’re more open to sharing it with others. A referral message sent shortly after this moment will likely feel natural and welcomed.

For example, if someone just got quick help from a call center support agent and rated it a 5, that’s a small moment of delight you can build on. A short message like:

“Glad we could help! Want to spread the word? Here’s a reward for sharing your link.”

Now it feels less like a pitch and more like a continuation of the good experience.

If you’re using tools like Intercom, Zendesk, or Help Scout, most of them let you collect CSAT automatically. You can use tools like Zapier to connect those responses with Tapfiliate, so happy users can be invited right after a high score comes in.

Unlike NPS, which focuses on the overall feeling about the brand, CSAT is tied to a single moment. That’s what makes it helpful in spotting referral opportunities when the mood is positive and recent.

You don’t need to guess who’s satisfied. You already know, as they just told you. All you’re doing is making it easy for them to share their experience while it’s still fresh.

3. CES: Spot customers who had a smooth experience

The Customer Effort Score (CES) tells you how easy or difficult it was for someone to complete an action such as solving a problem, using a feature, or checking out.

The question usually looks like this:

“How easy was it to do [X]?”

Respondents answer on a scale, typically 1 (very difficult) to 5 or 7 (very easy).

You can calculate the average score like this:

CES = Total score from respondents ÷ Number of respondents

So, why does this matter for referrals?

A higher CES score means the experience felt smooth. And that’s important for referrals because if someone feels like they didn’t have to work hard to get value from your product, they’re more likely to share it.

People don’t usually recommend products just because they’re happy. They recommend them when things feel simple and clear, including setup, support, and everyday use.

For example, if someone finds it easy to set up their referral link and understands how rewards work, they’re less likely to drop off. The same logic applies to the product itself. A low-effort experience is easier to talk about and recommend.

You can send CES surveys after:

• Product onboarding
• A help center visit
• A task that often causes drop-off (like importing data or setting up integrations)
  

If someone gives you a high score (like 6 or 7 out of 7), that’s a cue to reach out. You don’t need to wait for an NPS survey weeks later. You already know the interaction went smoothly.

You can also use CES tools as a filter to spot weak points. If certain parts of your product consistently get low CES scores, that might explain low referral activity there. People don’t share what feels like a hassle.

On the other hand, high CES moments give you a small window to act while the experience is still top of mind.

4. Repeat purchase rate: Identify customers with trust and buying intent

Repeat Purchase Rate (RPR) tells you how many customers returned to buy again. It’s one of the easiest ways to spot loyalty.

The formula looks like this:

RPR = (Number of returning customers ÷ Total number of customers) × 100

Loyal customers are usually happy to refer

A higher rate means more people choose to return after their first order. And that choice says a lot. It shows the product met their expectations, the experience was smooth, and there’s enough trust to spend again.

These are the customers most likely to refer. They’ve already gone through the whole cycle: discovery, purchase, use, and then return for more. That means they’re not guessing when they talk about your brand; they’re speaking from repeat experience.

Grouping these users before reaching out with a referral invite is helpful. For example:

• Customers who placed 2+ orders in the last 3 months
• Subscribers who upgraded their plan twice
• Users who reorder on a regular schedule

These customers could easily be identified in your CRM. You don’t need to pitch them with a salesy message. A simple question like “Want to share this with a friend?” works better when sent after a second or third order, because the trust is already built by that point.

But manually checking who placed multiple orders eats into your day. That’s time better spent running campaigns or testing referral offers.

With Tapfiliate, you can trigger a referral invite the moment someone places their second order. Connect it with your eCommerce platform through Zapier, and the invite goes out automatically, right when trust is high and the experience is still fresh.

5. Customer lifetime value (CLV): Target your most valuable users

Customer Lifetime Value (CLV) shows how much revenue a customer is expected to bring over the time they stay with your brand. It helps spot users who keep buying, stick around longer, and bring more value than one-time shoppers.

The formula looks like this:

CLV = Average purchase value × Purchase frequency × Customer lifespan

These customers trust you and are worth incentivizing

When you run a referral program, focusing on high-CLV users can bring stronger results. These customers already trust your product, are more familiar with your brand, and usually have better stories to tell. Their referrals often bring in people who match their buying habits.

And the numbers back this up. Motista studied 100,000 U.S. customers across 100+ brands and found that emotionally connected customers:

• Spend up to 2x more with their favorite brands.
• Have 306% higher lifetime value
• Stay loyal for over 5 years on average (compared to just 3.4 years)
• Recommend brands over 3x more often (30.2% vs. 7.6%)

These are the users worth incentivizing. Instead of offering the same rewards to everyone, you can provide higher perks to your top-tier customers or run a limited referral challenge just for them.

Tapfiliate lets you create custom reward tiers, so you can adjust incentives based on performance. If a high-CLV customer brings in three more just like them, it pays off, not just once, but across months or years.

6. Retention and churn: Focus on satisfied users who stay

Retention shows you how many customers continue using your product over time. Churn tells you how many leave. Tracking both gives you a clear picture of whether people find long-term value in what you offer.

The formula for churn is:

Churn Rate = (Customers lost during a period ÷ Total customers at the start of that period) × 100

If someone has stuck around through multiple renewals, product updates, or even a few support tickets, and still chooses to stay, it’s a sign they’ve found what they were looking for. They’re not here out of habit. They’re here because the product fits into their routine.

Instead of inviting every user to your referral program, you can focus on the ones who’ve already stayed beyond the average churn point. For example:

• Customers with a subscription older than 6 months
• Users who have renewed at least twice
• Long-time users who’ve given positive support feedback

These people are more likely to refer because they’ve had time to form a full opinion. A quick referral after sign-up might come too early before any real experience forms.

Finally: 

The most effective referral programs are the ones targeted at satisfied customers. They are the ones who recommend your product with certainty, vouch for their suggestion, and even help others resolve issues. Now, to identify them, you don’t need to rely on guesswork. Some customer satisfaction KPIs can measure your customers’ satisfaction level and convey it through numbers. We just talked about these KPIs, so feel free to use them the next time you want to run a customer referral program.