What Is Customer Acquisition Cost?
CAC is what you spend to win a customer. Blended and paid CAC answer different questions. This article lists what belongs in that spend—and what does not.
Customer acquisition cost (CAC) is how much you spend to gain a new customer.
CAC = acquisition spend / number of new customers
Same period on both sides. Use the customer acquisition cost calculator. CAC is a cousin of ROAS: ROAS thinks in revenue per ad dollar; CAC thinks in people. When AOV changes, they disagree. That is useful.
CAC only means something next to what you earn after variable costs from that customer over time—see Customer Lifetime Value Explained and the LTV calculator. Comparing CAC to revenue is how stores celebrate unprofitable growth.
Blended vs paid CAC
Paid CAC uses a spend pile that is mostly media (and maybe affiliates or influencers you treat as acquisition). Denominator: new customers you are willing to attribute to paid, or all new customers if you want a conservative number.
Blended CAC uses a wider spend pile (paid + tools that exist to acquire + sometimes marketplace ads) divided by all new customers, including SEO, direct, and email.
| Paid CAC | Blended CAC | |
|---|---|---|
| Question | What did paid acquisition cost per new customer we count? | What did it cost to add a customer to the file, all in? |
| Spend | Media, affiliates, maybe agency | Often the above plus more channels |
| Denominator | New customers (paid-attributed or all) | Usually all new customers |
| Failure mode | Looks cheap if organic is doing the work and you still divide by all new customers | Looks expensive if you dump brand spend into the numerator |
Pick one primary definition for the weekly meeting. You can compute both; you cannot average them into one “CAC” without a footnote.
Marketplace-first brands should not pretend Amazon Ads are comparable to D2C Meta without also modeling marketplace fees on the contribution side.
What to include in spend
Write a list. A reasonable paid acquisition numerator:
- On-platform media (search, social, shopping, retail media).
- Affiliate commissions for new customers (if you can split new vs repeat).
- Agency or freelancer fees that exist only to run those programs.
- Creative production you would not buy without ads (optional; be consistent).
A reasonable blended numerator adds:
- Other measurable acquisition (influencers treated as ads, comparison-shopping feeds).
- Sometimes a share of SEO retainers—only if you are explicit that this is fully loaded.
Usually leave out of classic CAC:
- COGS, shipping, payment fees (those belong in contribution and LTV, not in CAC).
- Warehouse rent and pick-and-pack for all orders.
- Founder salary unless you are doing a fully loaded investor model and say so.
- Retention tools (email platform) if their job is repeat purchase—those sit closer to LTV.
Including everything is “fully loaded unit economics.” That model is valid. Calling it CAC while another slide uses unpaid media-only CAC is how arguments start.
New customers
Define new:
- First paid order ever (recommended for D2C).
- First order in a trailing window (if you cannot identity-match; say so).
- Exclude returning customers from the denominator even if they clicked an ad.
If COD is common, consider new delivered customers rather than checkout GMV—see COD vs Prepaid Orders. Paying CAC on orders that never cash is fiction.
How CAC relates to ROAS and ROI
High ROAS with rising AOV can hide a CAC that no longer fits first-order contribution. Low ROAS on a subscription might still be fine if you trust LTV and payment survival.
ROAS vs ROI is the media-vs-investment frame. CAC vs LTV is the customer frame. You want both on the metrics dashboard.
Practical cadence
- Lock definitions in a one-pager.
- Export new customers from the commerce platform (first-order flag).
- Export spend from ads and affiliates for the same dates.
- Compute paid and blended separately.
- Compare to first-order contribution and to a conservative LTV range—not to a single magic LTV.
Organic is not free CAC
Blended CAC includes customers who arrived from SEO, email, and direct. Those channels have cost (content, tools, discounts in email). If you treat organic new customers as zero-cost in paid CAC’s denominator while celebrating a low paid CAC, you hid the mix. Either:
- Paid CAC = paid spend / paid-attributed new customers, or
- Blended CAC = selected spend / all new customers,
and you never divide paid spend by all new customers unless you are deliberately making paid look cheaper.
Affiliate networks: count commission on new customers in CAC if that is how you pay. Repeat-affiliate orders are closer to a selling cost on LTV, not acquisition.
When CAC should not be the weekly north star
Wholesale and long B2B cycles, or a launch week with one huge order, will spike the ratio. Use a rolling 28-day window or a note on the dashboard. Marketplace ads plus D2C ads should not share a CAC unless contribution stacks are similar.
Refunds and chargebacks after the first order do not change the new-customer count, but they change whether that CAC was worth it. Pair CAC with first-order contribution net of early returns when return rates are material.
Influencer seeding (free product) is acquisition cost in kind. If you ignore it, paid CAC looks better than the full picture.
The e-commerce analytics guide slots CAC into reporting. Cheap acquisition of the wrong customer (wrong SKU, high return) is still expensive. Fix merchandising and conversion as well as bids.
Key takeaways
- CAC = acquisition spend / new customers in the same period. The definition of both sides must be written down.
- Paid CAC uses ad (and similar) spend only. Blended CAC includes more channels and often organic, email, and marketplace.
- Leave out costs that would exist with zero new customers unless you are doing a fully loaded model on purpose.
- Compare CAC to contribution LTV, not to revenue. A cheap customer who returns the goods is not cheap.
Frequently asked questions
Should I include salaries in CAC?+−
Include people whose job is primarily acquiring new customers if you want a fully loaded CAC. Exclude warehouse and support that scale with all orders unless you are building a fully loaded unit economic model. Do not mix loaded and unpaid CAC in the same chart.
New customers or all orders?+−
Classic CAC uses new customers. Using all orders turns the metric into a cost-per-order hybrid that hides retention. If you need cost per order, name it that.
How often should I calculate CAC?+−
Monthly is a common operating cadence. Match spend and new customers to the same window. Ads paid in March that convert in April will skew a single week; use a lag you can live with and stay consistent.
Related tools
- Customer Acquisition Cost Calculator
Calculate CAC from sales and marketing spend and the number of new customers won.
- Customer Lifetime Value Calculator
Estimate simple LTV from AOV, purchase frequency and gross margin.
- ROI Calculator
Calculate return on investment from net profit and the amount invested.
- ROAS Calculator
Calculate return on ad spend from attributed revenue and ad cost.
Related guides
- E-Commerce Analytics Guide
Define the store metrics that matter, run a simple reporting cadence, stay humble about attribution, and connect numbers to decisions — not to dashboards for their own sake.
- E-Commerce Conversion Optimization Guide
Improve store conversion with research, hypotheses and honest changes to product pages, cart, checkout, trust and shipping promises — without dark patterns.
Related articles
- Customer Lifetime Value Explained
LTV estimates future contribution from a customer. Simple averages hide cohorts. Use a contribution model and treat precision as a range, not a forecast.
- ROAS vs ROI
ROAS measures media efficiency. ROI measures return after costs. Use this comparison to pick the right question for ads, margin and contribution profit.
- What Is ROAS?
ROAS is ad revenue divided by ad spend. Useful for media, incomplete for profit. Learn the formula, break-even ROAS from margin, and attribution limits.