How to calculate CAC and payback: a guide with a CHF example

Customer acquisition cost (CAC) is your total marketing and sales spend divided by the number of new customers won in a period. The payback period tells you how many months it takes for a customer's gross margin to repay that cost. You can work out both in a handful of simple steps.

Updated: June 2026

Once you know these two numbers, you know whether growth is profitable or quietly burning cash. According to the Optifai Sales Ops Benchmark (April 2026, 939 companies), the median CAC payback period in B2B SaaS sits at around 15 months – a long stretch that shows just how much capital gets tied up in winning customers. That is precisely why you should know your own figures rather than trust a gut feeling.

What do CAC and payback actually mean?

CAC and payback are two linked unit-economics metrics. CAC measures what a new customer costs you to acquire. The payback period measures how long it takes that customer to repay the cost through their gross margin. Together they show whether your growth is sustainably financed.

CAC is purely a cost figure per customer won. The payback period relates that cost to monthly profit, answering the question that keeps every SME owner up at night: when do I get my money back?

Both metrics build on a solid understanding of your CRM data, because without clean numbers on deals and costs, every calculation is just guesswork.

What is the formula for CAC?

The CAC formula is refreshingly simple: divide your total sales and marketing costs for a period by the number of new customers won in that same period. The result is the average effort per new customer, expressed in CHF. The hard part is deciding which costs to include.

CAC = (marketing costs + sales costs) / number of new customers

Which costs you count makes all the difference. A complete CAC typically includes:

• Ad budget and campaign costs (Google, LinkedIn, trade shows)
• Salaries and commissions for marketing and sales
• A share of tool costs such as CRM, newsletter or analytics
• Agency fees and content production

What does not belong in CAC is the cost of serving existing customers or general admin. Keep new-customer acquisition cleanly separate from account management, or the number becomes useless.

How do you calculate the payback period?

The payback period divides CAC by the monthly gross margin per customer. Gross margin is the monthly revenue per customer minus variable costs. The result is the number of months until a customer has repaid the cost of acquiring them. It is the cash-flow view that CAC alone cannot give you.

Payback (months) = CAC / (monthly revenue per customer x gross margin)

If you use revenue instead of gross margin, your payback period looks far too optimistic. The clean version always factors in the margin, because only the gross margin actually contributes to repaying the cost.

Step-by-step guide: CAC and payback in CHF

You can run the whole calculation in six steps. All you need are your cost figures, the number of new customers and the average revenue per customer. Work through them in order – each step gives you a concrete intermediate result you can sanity-check.

1. Set the period. Pick a clean window, such as a quarter or a year. Outcome: a clearly bounded measurement period.
2. Add up acquisition costs. Sum all marketing and sales costs for the period. Outcome: your total costs in CHF.
3. Count new customers. Count only customers newly won in the period. Outcome: the number of new customers.
4. Calculate CAC. Divide the costs by the new customers. Outcome: your CAC per customer in CHF.
5. Work out gross margin. Multiply monthly revenue per customer by the gross margin. Outcome: the monthly gross margin in CHF.
6. Calculate payback. Divide CAC by the monthly gross margin. Outcome: the payback period in months.

A worked example in CHF

Take a fictional Swiss SME selling software on subscription. In one quarter it spends CHF 30'000.00 on marketing and sales and wins 20 new customers. Each customer pays CHF 250.00 per month, and the gross margin is 80 per cent. Here is how the numbers fall out:

CAC works out at CHF 30'000.00 / 20 = CHF 1'500.00. The monthly gross margin is CHF 250.00 x 0.8 = CHF 200.00. The payback period is therefore CHF 1'500.00 / CHF 200.00 = 7.5 months.

7.5 months is a healthy result: it sits well below the benchmark median and inside the range most investors treat as self-funding growth. If you understand how CRM pricing models work, you can see exactly how such tool spend feeds into your CAC.

What is a good payback period?

A good payback period in B2B SaaS is under 12 months; anything under 18 months still counts as healthy. Top-quartile companies repay the cost in 6 months or fewer. The shorter the period, the faster you can recycle cash into fresh growth instead of waiting it back.

These reference points come from the Optifai Sales Ops Benchmark (April 2026), broken down by annual contract value (ACV):

For smaller Swiss SMEs with affordable subscriptions, a payback period under 12 months is a realistic and healthy target to aim for.

How does CAC relate to customer lifetime value?

CAC only becomes meaningful in relation to customer lifetime value (LTV). The LTV:CAC ratio shows how much a customer brings in over the whole relationship versus what it cost to win them. A short payback period alone is not enough – the ratio has to stack up too.

The rule of thumb is a ratio of at least 3:1: every franc invested in acquisition should bring back roughly three francs over the customer's lifetime. This rule was popularised around 2010 by David Skok of Matrix Partners and remains the standard today. If your ratio falls below that, you are spending too much for too little lasting return.

A high LTV forgives a higher CAC, because repayment plays out over a longer relationship. This is exactly where customer retention pays off twice over.

How do you reduce CAC and payback period?

You cut CAC and payback with two levers: lower cost per new customer, or higher gross margin per customer. In practice, small consistent improvements across the whole funnel often beat one big dramatic lever. Both ends of the equation are worth working on.

Effective measures include:

• Improving conversion rates so fewer leads are needed per deal
• Strengthening cheaper, organic channels such as referrals and content
• Raising the average order value through upsells and bundles
• Reducing churn, which lengthens LTV and improves the ratio
• Tightening the sales process so deals close faster

A lean, well-maintained CRM helps here, because fewer leads slip through the cracks and sales moves faster. If you avoid the common CRM rollout mistakes, you often see an effect on conversion within just a few weeks.

What mistakes should you avoid in the calculation?

The most common mistakes come from sloppy boundaries and the wrong reference figures. If you mix account-management costs into CAC, or calculate with revenue instead of gross margin, you get numbers that look prettier than reality – and you end up fooling yourself.

Watch out for these pitfalls in particular:

• Ignoring timing lag. Costs and deals often fall in different periods; adjust for that.
• Forgetting salaries. Staff costs are usually the biggest single part of CAC.
• Hiding the margin. Without gross margin, the payback period is flattering nonsense.
• Lumping everything together. Calculate per segment or channel, or good and bad sources blur into one.

Frequently asked questions

What is the difference between CAC and payback period?
CAC is a cost figure: it tells you what a new customer costs on average to acquire. The payback period is a time figure: it tells you how many months it takes a customer's gross margin to repay that cost. The two always belong together as a pair.

Which costs belong in CAC?
CAC includes all costs of winning new customers: ad budget, salaries and commissions for marketing and sales, a share of tool costs, plus agency and content costs. It should not include the effort of serving existing customers or general admin, as that distorts the figure.

What is a good payback period for an SME?
For small Swiss SMEs with affordable subscriptions, a payback period under 12 months is healthy and realistic. The B2B SaaS benchmark median sits at around 15 months according to Optifai (April 2026). The shorter it is, the faster you can recycle cash into further growth.

Should I calculate with revenue or gross margin?
Always calculate with gross margin, meaning revenue minus variable costs. Only that portion actually contributes to repaying the acquisition cost. If you calculate with full revenue, you get a payback period that is too short and therefore misleading about your real economics.

How often should I measure CAC and payback?
A quarterly rhythm suits most SMEs: often enough to spot trends, rarely enough not to be fooled by monthly outliers. During rapid growth or when launching new channels, a monthly look at the trend is also worthwhile to catch problems early.

Do I need expensive software for this?
No. To get started, a spreadsheet and clean numbers from your CRM are enough. More important than the tool is the discipline of recording costs and deals consistently. A simple CRM gives you the raw data for this without any extra effort.

Your CAC and payback checklist

Before you start, run through these points. They make sure your numbers are reliable and that you draw the right conclusions from them rather than chasing a flattering figure.

• Measurement period clearly defined (quarter or year)
• All acquisition costs captured, including salaries and commissions
• Only genuine new customers counted
• Gross margin known and reflected in the contribution
• Calculated with gross margin rather than revenue
• Result benchmarked (target under 12 months)
• Broken out per channel or segment

When every box is ticked, you have an honest basis for your next growth decision. Start for free at advanzo.app – no credit card – and use your CRM as a clean data source for CAC and payback.