What is CPA?

CPA (Cost Per Action) is the ad spend per defined target action — purchase, signup, form fill, or app install. The simple formula hides complexity: every platform defines "action" slightly differently (Google: last-click conversion; Meta: 7-day click + 1-day view), so the same purchase can be double-counted across networks if attribution isn't reconciled.

// formula

// target CPA (tCPA)

Google Ads and Meta both expose tCPA automated bidding — you set a target, the algorithm bids to deliver actions near that price. Set it 30%+ below your historical average and the campaign starves; set it too loose and you buy low-quality actions.

// how to lower CPA

• Audience quality — switching from broad to ICP-aligned targeting cuts CPA 20-40%.
• Landing page conversion rate — same spend, 2x conversions = 50% lower CPA.
• Proper attribution — data-driven attribution removes double-counting and reveals true CPA.
• Negative keywords — cleaning search waste drops CPA within 1-2 weeks.

// CPA in context

CPA alone misleads. A high CPA is fine if AOV is even higher. Read CPA with AOV (average order value) and marginal ROI together. d-lens shows CPA, AOV, LTV and ROAS in a single panel so you don't over-optimize one metric at the expense of profit.