Set the profitability question first
The limit is the maximum CAC that keeps an acquired order profitable: CAC = acquisition spend ÷ new customers acquired. Set it from contribution profit, not an industry benchmark; the CAC calculator structures it using your figures. CAC measures new-buyer cost; MER measures total marketing spend against total revenue for whole-system review; attributed ROAS assigns revenue to advertising activity for channel or campaign decisions. Contribution profit, after direct selling and advertising costs, tests offer and order economics. ORVX reports these views with product, collection and customer profitability.
| Measure | What it shows | When to act on it |
|---|---|---|
| CAC | Cost to acquire each new customer | Set or enforce the acquisition limit |
| MER | Blended marketing efficiency across the store | Review total marketing investment |
| Attributed ROAS | Revenue credited to advertising activity | Adjust a channel or campaign |
| Contribution profit | Value left after direct selling and advertising costs | Check whether the sale is economically viable |
What belongs in acquisition cost
Include first-time-buyer acquisition costs: Google, Meta, TikTok and marketplace ads; affiliate or referral commissions; agency fees allocated to acquisition; and campaign creative. Include acquisition software, allocating a documented share for tools used across retention and acquisition. Include sponsorships only if intended to generate new customers and allocated consistently. Store-funded first-order coupons and prospecting promotions belong in CAC; record discounts separately when explaining order economics.
Choose one fixed customer definition: typically, a new customer is a person placing their first delivered order, not an order count or new Shopify profile. Divide same-period acquisition spend by those customers. For delayed campaign effects, use a consistent attribution window rather than moving spend between months. The CAC calculator applies the definition repeatedly.
Keep COGS, shipping and fulfilment, payment fees, returns, customer service, retention campaigns, general software and broad overhead separate from CAC. Sponsorships and brand creative without a defensible acquisition allocation remain brand spend. Decide whether figures are GST-inclusive or exclusive; GST in New Zealand is charged at a rate of 15% (IRD), so match treatment to recoverability and apply it consistently (Source: Inland Revenue (Te Tari Taake)).
Worked example with sample numbers
This example is illustrative. It uses sample numbers for a motorcycle gear store selling in New Zealand. They are made up to show the method, they are not a benchmark, and your own figures will differ.
Formula: Ceiling = margin per order x orders per customer / target ratio.
| Orders per customer | Margin earned | Ceiling at a 3:1 target |
|---|---|---|
| 1.0 | NZ$35.12 | NZ$11.71 |
| 1.5 | NZ$52.68 | NZ$17.56 |
| 2.0 | NZ$70.25 | NZ$23.42 |
| 3.0 | NZ$105.37 | NZ$35.12 |
Run the same sum with your own numbers in the free calculator, or browse guides for sellers in New Zealand and more motorcycle gear guides.
General information only: tax, duty and import rules change and depend on your situation, so check with an accountant or the official source before acting.
Eligible Shopify stores can see these numbers for their own store through the Founding 10,000 offer.
Use first-order margin as a hard ceiling
Set the ceiling from the first order’s contribution, not its sales value. Use realized revenue after delivery, then subtract product cost, payment fees, shipping subsidies, discounts, expected returns and every other cost that rises with the order. If a New Zealand price includes GST, remove GST before calculating; GST is charged at 15% (Inland Revenue).
Example: a delivered order produces $300 ex-GST revenue. Subtract $150 product cost, $8 payment fees, $15 shipping subsidy, $12 expected return cost, $30 discount and $5 packaging: $300 − $220 = $80 first-order contribution. CAC must be below $80 for that order to be immediately profitable; a $90 CAC loses $10 before fixed overhead. Use the CAC calculator to apply the same logic to your store.
| Include | Exclude |
|---|---|
| Product cost; payment fees; shipping subsidy; discounts; expected returns and refunds; packaging; other order-linked costs | Advertising and acquisition costs (tested against the contribution ceiling); fixed rent, salaries and software; GST collected on behalf of the government |
Let repeat purchases change the limit
Repeat purchases can support a higher allowable CAC, but count contribution margin, not repeat revenue. A practical limit is: first-order contribution + expected second-order contribution + later expected contribution, less any retention or service costs. For illustration only, a $50 first-order contribution plus a probability-weighted $30 second-order contribution and $15 from later orders gives a $95 long-run contribution limit before fixed costs. That is not permission to spend $95 automatically: the $45 of future contribution is conditional.
Test whether customers actually reorder, when those orders arrive, and whether returns reduce the contribution. Check that popular replacement items remain in stock; an expected repeat order cannot fund CAC if inventory is unavailable. Set a customer payback period as well: a customer may become profitable after 18 months but still strain cash if acquisition spend is recovered only then. ORVX shows customer-level profitability and repeat behaviour, reports return rates and refund value, and keeps realized revenue tied to delivered orders. Use those observed results to revise the repeat-order assumptions, rather than treating projected lifetime value as a fixed figure.
Track CAC by channel and customer cohort
Track paid social, paid search, email-assisted acquisition, affiliates, organic activity and offline campaigns under one attribution rule. For each new-customer cohort, record delivered first-order revenue, acquisition cost and contribution after CAC. Keep assisted conversions visible: an email click may close a sale that began with search or social, while an affiliate commission may be charged at the final step. Changing the rule between channels makes CAC comparisons unreliable.
Blended CAC is the right measure for the store’s overall acquisition budget: total acquisition cost divided by new customers. Use channel CAC to decide whether to scale, reduce or test a source, checking whether it attracts customers with comparable order margins and repeat behaviour. When product mix varies, contribution after CAC is the action measure: a lower-CAC channel can still lose more if its orders have weaker margins.
Payback period is the right measure when cash timing matters, especially where repeat purchases take months. Compare cohorts by acquisition month and channel, rather than mixing new and returning customers. ORVX shows customer-level profitability and repeat behaviour, and tracks MER and attributed ROAS separately so channel efficiency is not confused with total-store efficiency. Use the CAC calculator to test inputs consistently.
Read the worked example as a decision tool
Read the worked example as a set of decision checks, not as a quoted New Zealand rate. Start with the first-order ceiling: the contribution left after the initial delivered order and its variable costs. If your actual CAC is above that amount, the first order does not pay for acquisition; reduce spend, improve the offer, or fix the order economics before scaling that channel. This is the immediate test because it does not depend on customers buying again.
Then compare it with the repeat-purchase allowance. That higher limit is justified only by the contribution margin from expected future orders, tied to a defined cohort window, not by repeat sales alone. Recheck every input: GST treatment, discounts, delivery costs, payment fees, returns, product cost, attribution, repeat rate, order frequency and the period covered. A small change in any assumption can move the limit materially. Use the CAC calculator to stress-test alternatives, but do not treat the result as a market benchmark or permanent target. It is your current decision limit under stated assumptions; revise it when prices, costs, mix, channels or customer behaviour change.
A motorcycle gear store in New Zealand should treat allowable CAC as a financial limit built from its own contribution margins and customer behaviour. Use first-order economics to protect cash flow, repeat-purchase evidence to justify investment beyond that limit, and channel-level tracking to decide where the next dollar of acquisition spend belongs.
Sources
- GST (goods and services tax) (Inland Revenue (Te Tari Taake), checked 26 October 2026).
How this page was made: drafted with AI from a brief, then checked by automated rules for arithmetic, sources and duplication. The sample numbers were calculated, not reported.