New-customer cost rises as ads cost more or response falls

What you see

New-customer acquisition cost rises. Impression price, click rate, purchase rate, or new-customer share explains the arithmetic change.

Illustration: higher impression cost raises acquisition cost while other inputs stay constant. — Only impression cost changed.

Check this first

Break the cost into its measured parts before changing ads, bids, or landing pages.

Data needed

Spend, impressions, clicks, purchases, and new customers for the same population
Campaign, placement, device, and date
Attribution settings and purchase-delay coverage

Run the check

#1
Confirm that spend, impressions, clicks, orders, and new customers describe the same population.
#2
Compare each factor over equally mature periods.
#3
Hold mix constant where practical and measure each factor’s contribution to the change.
#4
Investigate the factor that changed, using campaign and source settings.

Calculate

For one aligned click-based population: spend/new customers = CPM / (1,000 × clicks/impressions × orders/clicks × new customers/orders). If populations don't align, report the factors separately and show the unexplained difference.

Compare groups

Channel and campaign
Audience and placement
Device
Product and promotion period

What a healthy result looks like

The measured factors reconcile to the cost change. The resulting acquisition cost remains within the brand’s stated limit.

When to investigate

Use the brand’s comparison range and acquisition limit. No universal CPM, click-rate, or purchase-rate cutoff applies.

Possible causes

CPM increased.
Click-through rate declined.
Purchase conversion rate or new-customer share declined.

Rule out these explanations

View-through orders mixed with click-based orders
Changed placement, device, or customer mix
Different click and conversion dates

What to do next

Investigate price, click response, purchase response, or customer mix according to the measured change. Change one relevant factor in a controlled test.

What this check can tell you

This calculation locates the cost change. It doesn't identify the cause of a lower click or purchase rate.

Use this check with AI

Run a read-only check for: New-customer cost rises as ads cost more or response falls.
First confirm the available sources, columns, row grain, date basis, currency, and customer definition. Use only authorized data.
Required inputs: Spend, impressions, clicks, purchases, and new customers for the same population; Campaign, placement, device, and date; Attribution settings and purchase-delay coverage.
Check: New-customer acquisition cost rises. Impression price, click rate, purchase rate, or new-customer share explains the arithmetic change.
Calculate: For one aligned click-based population: spend/new customers = CPM / (1,000 × clicks/impressions × orders/clicks × new customers/orders). If populations don't align, report the factors separately and show the unexplained difference.
Slice by: Channel and campaign; Audience and placement; Device; Product and promotion period.
Use this comparison rule: Use the brand’s comparison range and acquisition limit. No universal CPM, click-rate, or purchase-rate cutoff applies.
Show the source totals, calculation, unknown groups, missing inputs, and result. Don't invent fields, thresholds, customer matches, or causal effects.
Rule out: View-through orders mixed with click-based orders; Changed placement, device, or customer mix; Different click and conversion dates.
Describe the observed signal separately from possible explanations. If the check is incomplete, state the exact data needed.
Make no account or budget changes.

Sources and definitions

Google: attribution settingsTime zone, attribution settings, and conversion windows affect comparisons.Read source