CPC is spend per click; CPA is spend per conversion. Together they connect ad budget to results — and CPA × orders shows what acquisition really costs.
The example
$5,000 spend, 2,500 clicks, 120 orders.
| A | B | |
|---|---|---|
| 1 | Metric | Value |
| 2 | CPC | $2.00 |
| 3 | CPA | $41.67 |
The formula
The formula:
How it works
How it works:
- CPC = ad spend ÷ clicks — the price of a visit.
- CPA = ad spend ÷ conversions — the price of a customer or order.
- CPA =
CPC / conversion_rate— cheaper clicks or better conversion both cut it. - Compare CPA to margin per order to see if the channel is profitable.
CPA is the one that matters. A low CPC looks great but means nothing if those clicks don’t convert — CPA = CPC / conversion_rate. A $0.50 click at 1% conversion is a $50 CPA; a $2 click at 8% is a $25 CPA. Optimize toward CPA (and profit per order), not cheap clicks.
Try it: interactive demo
Spend, clicks, conversions.
Variations
Cost per acquisition
Per order:
CPM (per 1000 impressions)
Awareness cost:
CPA from CPC
The link:
Pitfalls & errors
Cheap clicks can mislead. Low CPC with poor conversion = high CPA. Optimize for CPA.
CPM is per 1,000. Multiply by 1000 after dividing by impressions.
Profit check. CPA must sit below margin per order to be profitable.
Practice workbook
Frequently asked questions
How do I calculate CPC and CPA in Excel?
How are CPC and CPA related?
What is CPM?
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