CAC Calculator

How to use the CAC calculator

1. Pick one period. Last month or last quarter both work. Every number you enter must come from that period.
2. Ad and marketing spend: what you paid for ads, sponsorships, content, events and anything else meant to bring in customers.
3. Other sales and marketing costs: pay and commissions for anyone who sells or markets, freelancers, and tools such as an email platform. Enter 0 if you have none.
4. New paying customers: people who paid you for the first time in the period. Do not count leads, signups or free users.
5. Monthly revenue per customer and gross margin (optional): fill these in to see the payback period. Gross margin is the share of revenue left after the direct cost of serving a customer.

The result updates as you type. It shows your CAC, your total spend, the gross profit one customer brings in each month, the payback period and how many customers $1,000 buys you at this rate.

The CAC formula

This is the blended version of customer acquisition cost: it divides all spend by all new customers, including the ones who found you through word of mouth. It is the most common way to state CAC and the right one for a first look. The payback part uses gross profit, not revenue, because only the money left after serving a customer can pay back what you spent to win them.

A worked example

Say you run a small subscription product. Last month you spent $2,400 on ads and $600 on a freelance writer and an email tool. You won 40 new paying customers. Each pays $30 a month and your gross margin is 80%.

So each customer costs $75 to win and has paid that back early in their fourth month. If only 20 customers had signed up for the same spend, CAC would double to $150 and payback would stretch to 6.3 months.

How to read your CAC

There is no good CAC on its own. A $500 CAC is fine if a customer brings you thousands in profit and ruinous if they bring you $50. Read it against two other numbers.

• Payback period. This is how long your cash is tied up in each new customer. In his widely read SaaS Metrics 2.0 guide, investor David Skok shows that profitability suffers when it takes longer than 12 months to recover CAC. That guide is about software subscriptions, so treat it as a reference point, not a rule for every business. The calculator turns the result green at 12 months or less.
• Lifetime value. Compare CAC with what a customer is worth over the whole time they stay, using the LTV calculator. The same guide says the strongest software businesses have an LTV more than three times their CAC.
• Your cash. A short payback matters most when money is tight. Check how many months you can fund with the startup runway calculator.

How to lower your CAC

• Win the first customers by hand. Direct messages, communities and people you already know cost time, not ad money. See how to find your first 10 customers.
• Narrow who you sell to. A clear ideal customer profile means fewer wasted clicks and calls.
• Fix the leaks before buying more traffic. If visitors do not sign up, more visitors will not help. Work on the page, the offer and the price first.
• Split CAC by channel. Run the calculator once per channel with only that channel's spend and customers. Stop paying for the ones that cost the most per customer.
• Test demand before you spend. Founders often pay high CAC because the problem is not painful enough. Validate the idea with real conversations first.

What the calculator leaves out

• Timing. It assumes the customers you won this period came from this period's spend. If your sales cycle is long, last quarter's spend may be what won this month's customers.
• Paid versus organic. It gives one blended number. It does not separate customers who came from ads from those who came for free.
• Your own unpaid time. If you do the selling yourself and take no pay, your real cost is higher than the number shown.
• Churn and upgrades. Payback assumes every customer keeps paying the same amount each month until the cost is recovered. Customers who cancel early never pay it back.
• Discounts, refunds and onboarding costs are not included unless you add them to your spend.