“We know our sitewide CAC goal is $40, so all channels should be targeting a $40 CPA, right?”

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This assumption comes up constantly, as many brands default to arbitrary benchmarks or copy industry averages, while others assign the same goal to every channel.

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Both approaches miss the point: channel goals only matter if they ladder up to sitewide CAC.

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Why This Matters at the Business Level

At the end of the day, you don’t deposit Meta CAC or TikTok CAC into the bank, you deposit profit. That’s why Sitewide CAC (or MER) is the only number that matters.

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If your sitewide CAC is on target, the business is healthy. If it isn’t, nothing else matters. Channel CPAs must be managed in the context of how they affect the blended number, Not necessarily.

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And because influencer spend often doesn’t have trackable conversions, it should be treated as a variable cost in the model. Instead of assigning it a CPA, you add it into total spend so it weighs against sitewide CAC. This way, your regression accounts for influencer dollars even if attribution doesn’t.

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How to Set Channel Goals (Step by Step)

1. Map All Spend and CPAs in One Daily View

Build a sheet with every channel: Meta, Google, TikTok, plus influencer spend.

Track daily spend, conversions, and CPA for the paid channels.

Add influencers as spend-only to make sure the blended CAC reflects reality.

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2. Run Regression to Tie Channels to Sitewide CAC

Regression shows how tightly a channel’s CPA moves with sitewide CAC. This lets you calculate the CPA ceiling for each channel that still keeps the blended goal intact.

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Here’s a 14-day lookback regression formula in Google Sheets (replace “20” with your site goal, and “14” with the number of days that you would want to view):

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1=INDEX(
2  LINEST(
3    FILTER(
4      S10:S,
5      (S10:S>0)
6      * (W10:W>0)
7      * (A10:A >= MAX(A10:A) - 14)
8    ),
9    FILTER(
10      W10:W,
11      (S10:S>0)
12      * (W10:W>0)
13      * (A10:A >= MAX(A10:A) - 14)
14    ),
15    FALSE
16  ),
17  1
18) * 20
19

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Where:

• S10:S = channel CPA series
• W10:W = sitewide CAC series
• A10:A = date column (daily granularity)
• Output = regression-informed channel CPA target aligned to the sitewide goal (in the example above $20(+)

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3. Apply Nuance by Channel

• Meta: Volatile but scalable. If it trends below sitewide CAC, push aggressively.
• Google: Often higher CPA but adds incremental demand. Allow a cushion above target.
• TikTok: Early-stage, higher variance. Regression will show whether its CPA is helping or hurting blended CAC.
• Influencer: Don’t assign a CPA. Just account for its spend in the total so it’s weighing the blended CAC appropriately.

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4. Use multiple windows & refresh

Run 7/14/30-day lookbacks. Short windows catch shifts; longer windows stabilize targets. Recompute targets weekly (or daily at scale).

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Metrics That Matter

• Sitewide CAC (daily): Non-negotiable North Star.
• Channel CPA vs. regression-based target: The operational lever to scale, hold, or cut.

Takeaway

Channel goals shouldn’t be guesses or borrowed benchmarks.

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Tie each channel’s CPA to sitewide CAC via regression, treat influencer as spend-only, and update targets on rolling lookbacks. You’ll know exactly how strict or flexible to be on Meta, Google, TikTok, and influencer, with goals that actually protect the business.

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How We Can Help

We constantly and consistently build regression-driven, trend aware dashboards that keep every channel accountable to sitewide CAC. If your channel targets feel disconnected from results, we’ll connect the dots so budget decisions get simpler, and more profitable.

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