A campaign with a high ROAS can still leave the business short of cash. A channel with a low CAC does not necessarily bring good customers. CAC, LTV and ROAS are only useful when calculated consistently and read next to margin, cash flow and payback period.

You do not need a complex financial model to start. What matters more is defining clearly which costs are included, which revenue has actually been recognised, and how differently each customer group behaves.

CAC: the cost of acquiring one customer

CAC is total sales and marketing spend in a period divided by the number of new customers it produced. Beyond the ad budget, include people, tools, content production, commissions and agency fees where they serve customer acquisition.

Note: Do not compare a channel CAC that only counts ad spend with a company-wide CAC that includes salaries and tools; the two numbers use different definitions.

LTV: customer value across the relationship

LTV should reflect contribution profit, not just revenue. For repeat-purchase models you can start with average order value multiplied by purchase frequency and retention period, then multiply by the margin. When data is thin, use conservative estimates and update them per customer group.

ROAS: revenue per unit of ad spend

ROAS is the revenue attributed to advertising divided by the advertising cost. It is easy to read but does not deduct cost of goods, payment fees, operations and refunds. The break-even ROAS for a business with a 30% gross margin is very far from one with an 80% margin.

Read the three together

  • ROAS shows how efficiently the ad budget generates short-term revenue.
  • CAC shows the total cost required to win a new customer.
  • LTV shows whether you can recover CAC and profit afterwards.
  • Payback period shows how long the business must fund its own growth.
  • Cash flow shows whether the current pace of expansion is affordable.

A reporting process you can audit

  1. 01

    Lock the definitions

    Write down the data source, the time window and which cost types belong in each metric.

  2. 02

    Break it down

    View by channel, campaign, product and customer group rather than one average number.

  3. 03

    Reconcile

    Compare the revenue in the ad tool against orders, refunds and money actually received.

  4. 04

    Decide

    Raise the budget when profit and payback allow it, not just because the dashboard is green.

UTM is a set of parameters added to a URL so analytics tools can identify the source, medium and campaign of a visit. Used consistently, UTM answers which content brings customers rather than just clicks.

UTM does not create accurate data on its own. You still need a naming convention, link checks and connected conversion events. If everyone writes tags their own way, one channel gets split across several rows in the report.

The 5 common UTM parameters

  • utm_source: the specific source sending the traffic, such as a newsletter or a partner name.
  • utm_medium: the channel type, such as email, social, referral or paid_social.
  • utm_campaign: a consistent campaign name based on the goal or the period.
  • utm_content: distinguishes the ad creative, the button or the content variant.
  • utm_term: records the keyword group or targeting criteria when you genuinely need it.

Build a naming convention you can manage

  • Use lower case and one consistent separator.
  • No spaces, no accented characters and no per-person spelling variations.
  • Names should describe the source and purpose but contain no personal data.
  • Store every link in a shared sheet with an owner and a creation date.
  • Define the list of valid values for source and medium.

An example link structure

Example URL 
https://example.com/san-pham?utm_source=newsletter&utm_medium=email&utm_campaign=ra_mat_thang_09&utm_content=nut_chinh

Note: Never put an email address, phone number, customer name or sensitive data into URL parameters, because links show up in browsing history, server logs and third-party reports.

How to roll it out and check it

  1. 01

    Build links from a standard template

    Pick values from the agreed list instead of typing them freely each time.

  2. 02

    Check the landing page

    Open the link, confirm the page loads and that the parameters do not break a redirect or the checkout.

  3. 03

    Check the report

    Confirm the session appears under the correct source, medium and campaign in your analytics tool.

  4. 04

    Attach conversions

    Track sign-ups, enquiries, checkout starts and transactions to judge traffic quality.

How to read the report correctly

Compare campaigns by cost, conversions, revenue and profit rather than by visits alone. A channel may support the customer early in the journey without being the last touch, so also read the conversion paths and ask customers how they found you.

  • Separate new and returning customers when judging performance.
  • Check for conversion windows longer than a single session.
  • Reconcile revenue with the order system rather than trusting one report.
  • Note major changes to content, budget or landing pages.