CAC in marketing: how to calculate acquisition cost
CAC (Customer Acquisition Cost) measures how much it costs to acquire each customer. Learn to calculate it correctly, understand the LTV/CAC ratio, and...

A user's first contact with your product is, arguably, the most important moment in the entire relationship. In the first few minutes they decide whether it is worth continuing or closing the tab forever. Digital onboarding is the discipline that turns that first contact into real activation.
Digital onboarding is the guided process that takes a new user from registration to the moment they experience the core value of the product for the first time. In SaaS it is called the "aha moment": the instant when the user understands why they should stay.
It is not a tutorial. It is not a series of automated emails. It is an experience designed to reduce the friction between "I just signed up" and "this solves my problem."
Poor onboarding is the primary cause of early churn. According to industry studies, more than 60% of users who register for an application do not return after the first day if they have not managed to complete a value action.
In ecommerce, onboarding is equivalent to the first steps of a new buyer: how they navigate, how they filter, whether they understand the categories, whether the purchase process builds their trust. In SaaS, it is the time between registration and the first retention action (creating a project, connecting an integration, sharing with a colleague).
Every friction point in that journey is a missed conversion opportunity. And more costly: a missed long-term retention opportunity, because users who activate correctly have a 30-day retention rate up to three times higher than those who do not.
The most common onboarding mistake is trying to teach everything at once. A 12-step checklist on the first screen creates paralysis, not action.
Progressive disclosure means revealing features as the user needs them. In practice this means:
Notion applies this well: upon registration, the user sees an almost empty screen with a single invitation to create their first page. There are no overwhelming side menus, no forced tours. Complexity appears when the user seeks it.
One of the best ways to accelerate activation is to personalize onboarding based on the user's profile. Asking during registration "what are you going to use this product for?" is not just a marketing survey: it is information that allows the first steps to be adapted to the real use case.
Slack does this by asking whether you are using the tool for work, a personal project, or a community. Depending on the answer, the initial steps change. The result is that the user reaches the aha moment faster because the path is tailored to their context.
In ecommerce, onboarding personalization can be as simple as asking style or size preferences on first access to improve catalogue recommendations.
Welcome checklists with a completion percentage are a classic of onboarding gamification. LinkedIn popularized this technique with its "profile completeness" bar. The principle is simple: humans tend to complete what they have started.
Applied to digital onboarding:
Duolingo built its entire retention model almost entirely on onboarding gamification: daily streaks, points, leagues. The result is an anomalous retention rate for a learning app.
Onboarding does not end when the user closes the app. A well-designed email sequence extends the process and re-engages users who stopped halfway.
The most effective activation emails:
Real example: Grammarly sends an email at 24 hours with the number of words the user has corrected and a message about the impact it has had. It does not sell. It shows value. And that brings the user back.
You cannot improve what you do not measure. The key onboarding metrics are:
| Metric | What it measures | Typical target |
|---|---|---|
| Time to first value | Time from registration to first value action | Under 5 minutes |
| Activation rate | % of sign-ups that complete the activation action | Above 40% |
| Drop-off by step | Where in the flow users abandon | Identify the bottleneck |
| D1/D7/D30 retention | % of active users at 1, 7, and 30 days | Benchmark by sector |
Analyzing drop-off by step is especially valuable: if 70% of users abandon at step 2 of 5, the problem is there, not in the rest of the flow.
In online stores, the new buyer's onboarding has its own characteristics. The goal is not to teach how to use a tool, but to build enough trust for the user to make their first purchase.
The most effective levers in ecommerce:
Post-purchase onboarding also counts: a well-designed confirmation email that explains what happens next, when the order will arrive, and how to get in touch if there are questions reduces buyer anxiety and increases the likelihood of a repeat purchase.
Forced, non-skippable tour. Users who want to explore on their own get frustrated with modals that block the interface. There should always be an option to skip.
Too much information at once. Cognitive overload is real. More steps do not mean more learning; they mean more abandonment.
Onboarding disconnected from the real product. If the tour shows features the user will not use in the first few days, it creates confusion instead of clarity.
Not measuring or iterating. Onboarding that nobody analyzes does not improve. Continuous iteration based on behavioral data is what generates real improvements in the activation rate.
CRO applied to onboarding works exactly like in any other funnel: identify where people drop off, formulate hypotheses about why, design experiments, and measure the impact.
The difference is that here the impact multiplies: a 10% improvement in activation rate can represent a 20-30% increase in 30-day retention, which in turn translates into more trial-to-paid conversions or more repeat purchases.
If you want to improve your product's activation and retention with a rigorous experimentation methodology, our CRO team can help.
View CRO servicesOr start today by auditing your conversion funnel for free:
Audit your site for free with Scan&BoostAdrià Vidal is a conversion optimization and growth specialist at Boost. He works with digital companies to improve their activation, retention, and conversion rates through data-driven experimentation. Connect on LinkedIn
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