What Is CPA (Cost per Acquisition)?
CPA (Cost per Acquisition) is the ad spend required to generate one conversion — usually a purchase, lead, signup, or install. It's the operational number ad platforms optimise toward and the number that decides whether a campaign can scale profitably.
Formula
The 'conversion' must be defined the same way every time — if you sometimes count leads and sometimes count qualified leads, CPA becomes meaningless. Pick one primary conversion per campaign objective and stick to it.
Worked example
You spend $2,400 on a lead-gen campaign and Meta reports 60 leads. CPA = $2,400 ÷ 60 = $40 per lead. If your sales team closes 20% of leads at $600 gross profit each, contribution per lead is $600 × 20% = $120 — so $40 CPA is healthy. If close rate drops to 5%, contribution is $30 and you lose money at the same CPA.
Benchmarks
- D2C ecommerce (Meta): $15–$45 CPA at $60+ AOV is typical breakeven zone.
- B2B lead-gen (LinkedIn / Meta): $30–$120 per marketing-qualified lead.
- SaaS free trial: $8–$40 per signup; scale gated by trial→paid conversion.
- Local services (Google Ads): $20–$80 per lead depending on category.
Why it matters
CPA is the honest gate for scaling. Every ad platform will happily spend more of your money at a rising CPA — most auto-bid strategies do exactly that. Setting a CPA ceiling tied to gross margin and close rate is how you stop the algorithm from turning your budget into low-quality volume.
Common mistakes
- 1.Setting a CPA target that ignores gross margin. Your CPA ceiling is a math problem, not a wish.
- 2.Chasing lower CPA by narrowing audiences. It works short-term, then CPMs explode and CPA rebounds.
- 3.Ignoring the funnel below the ad. A great ad + a broken landing page = high CPA. Fix the landing page first, always.
- 4.Comparing platform CPA and CRM CPA as equal. Platform CPA counts view-through and same-user cross-device; CRM does not.
Put CPA to work
Free calculators
Related services
FAQs about CPA
What is a good CPA?
A CPA below your contribution margin per customer. If a new customer earns you $100 of gross profit on the first order, any CPA under $100 buys growth — anything over $100 buys losses.
What's the difference between CPA and CAC?
CPA is per platform-reported action. CAC (Customer Acquisition Cost) is total marketing + sales spend ÷ new customers acquired — the company-level number your CFO uses.
How do I lower CPA?
In order of impact: (1) better creative (raises CTR, lowers CPC), (2) better landing page (raises CVR), (3) better offer, (4) broader audience with strong signal — narrower is not automatically cheaper.
Why does my CPA change every week?
Small conversion counts. Below ~50 conversions per ad set, weekly CPA swings ±30% are noise, not signal. Aggregate to 14- or 28-day windows to see the real trend.
Related terms
Revenue attributed to ads ÷ ad spend — the fastest efficiency read.
Spend divided by leads captured — a top-of-funnel efficiency metric.
Ad spend divided by clicks — what one click into your site costs.
% of clicks or sessions that complete the target action.
Average revenue per transaction — total revenue ÷ number of orders.
Lifetime value ÷ acquisition cost — the unit-economics gate for scaling.
How credit for a conversion is assigned across ad touchpoints.