CAC Payback Calculator
A cheap CAC means nothing if your margin can't pay it back. This shows how many orders it actually takes to recover what you spent acquiring a customer, based on your real margin — not just the CAC number by itself.
What your result means
The calculator shows how many orders a new customer must place before the gross profit from those orders covers what you paid to acquire them.
A result below 1 means the first order pays back the acquisition cost on its own. Above 1, you need repeat purchases to break even, so retention matters as much as the ad budget.
How the CAC payback formula works
Profit per order = Average order value × Gross margin Orders to pay back CAC = CAC ÷ Profit per order
- CAC
- customer acquisition cost = acquisition spend ÷ new customers acquired
- Average order value
- revenue ÷ number of orders
- Gross margin
- share of revenue left after product costs
This calculator measures payback in orders. The usual finance definition measures it in months:
CAC payback (months) = CAC ÷ Monthly gross profit per customer
The two are linked by how often customers buy. Orders to payback ÷ orders per customer per month gives payback in months.
Worked example
Worked exampleExample numbers
These match the calculator's default inputs.
| Input | Value |
|---|---|
| CAC | $40 |
| Average order value | $75 |
| Gross margin | 45% |
- Profit per order = $75 × 45% = $33.75
- Orders to pay back = $40 ÷ $33.75 = 1.2 orders
The first order recovers most of the $40. The customer pays back fully partway through their second order. If customers order once every two months, that's roughly 2.4 months.
How to shorten CAC payback
- Lower CAC by moving spend away from campaigns that don't break even. The Ad Profit Leak Score shows whether your ads cover their cost.
- Raise first-order value with bundles, thresholds and upsells. The AOV uplift calculator shows what it's worth.
- Improve gross margin through pricing and product costs.
- Bring customers back sooner with post-purchase emails and replenishment reminders for consumables.
The guide to customer acquisition cost covers blended vs paid CAC and payback in more depth. For ad-driven customers, the guide to ROAS and break-even ROAS shows how margin sets what you can afford to pay per sale.
Common mistakes with CAC payback
- Using blended CAC to judge a single channel. Blended CAC includes free organic customers, so it flatters paid channels. Use each channel's own CAC.
- Leaving out the welcome discount. If new customers get 15% off their first order, use the discounted first-order value, or add the discount to CAC.
- Assuming every customer comes back. If most customers buy once, a payback of 2 or 3 orders means most customers never pay back. Check your repeat purchase rate.
- Using revenue instead of gross profit. CAC is paid back from what each order earns after product costs, not from the order total.
- Ignoring time. Two orders over two months and two orders over two years are very different for cash flow. Convert orders to months using how often customers buy.
FAQ
How do I turn orders to payback into months?
Divide the orders to payback by how many orders a typical customer places per month. If payback takes 3 orders and customers order once every two months (0.5 a month), payback takes about 6 months.
How do I calculate CAC?
Divide what you spent to acquire customers in a period by the number of new customers you won in it. Paid CAC uses ad spend and the customers those ads brought in; blended CAC uses all marketing spend and all new customers.
What if the result says 'Never at this margin'?
That appears when gross margin is zero or negative, so no order earns back anything. Fix pricing or product costs before spending more on acquisition.