Facebook Ads vs Google Ads: One Report for Both Platforms

A large share of Meta Ads accounts also run Google Ads, more Meta Ads accounts pull Google Ads data in the same week than any other cross-platform pairing. If you’re one of them, the real question isn’t which platform is better, it’s how to compare them on one report without the numbers silently disagreeing.

Field mapping between the two platforms

The same metric often has a different field name and a slightly different definition on each platform. Here’s the mapping for the fields that matter most:

Metric	Meta Ads field	Google Ads field
Spend / cost	`spend`	`cost`
Impressions	`impressions`	`impressions`
Clicks	`clicks`	`clicks`
Click-through rate	`ctr`	`ctr`
Conversions	`actions_omni_purchase` (or the specific action type)	`conversions`
Conversion value	`action_values_purchase`	`conversions_value`
Campaign name	`campaign`	`campaign_name`
Account currency	`account_currency`	`account_currency_code`

The names line up more closely than the definitions do. “Conversions” on Google Ads is whatever you’ve marked as a primary conversion action in the account; Meta’s actions_omni_purchase and similar fields are specific action types. Match the actual business event, don’t assume “conversions” means the same funnel step on both sides just because the column headers look similar. If a Meta field name comes back “not valid,” see the Facebook Ads “Field Not Valid” error guide for the exact fix; Google Ads has its own field-combination guide for the equivalent problem on that side.

The blended ROAS method

Pull spend, conversions, and conversion value from both Meta Ads and
Google Ads for the last 30 days. Calculate ROAS for each platform
separately, then a blended ROAS across both combined. Show all three
numbers side by side.

Blended ROAS (total conversion value across both platforms divided by total spend across both) is the number that answers “is my ad spend working,” platform-level ROAS answers “which platform is more efficient.” Both matter, they answer different questions.

Three joins that go wrong

Date grains

Meta and Google don’t always close out a reporting day at the same time in every timezone setup. Comparing a Tuesday-to-Tuesday week from one platform against a slightly offset week from the other produces a mismatch that looks like a performance difference but is actually a date-boundary issue. Pull both on the same explicit date range, not a rolling “last 7 days” resolved separately by each platform.

Currency

If any account runs in a different currency, account_currency on Meta and account_currency_code on Google Ads tell you what you’re actually looking at before you add two spend numbers together. Adding raw spend across accounts in different currencies without converting first is a quiet way to get a blended number that means nothing.

Conversion definitions

“Conversions” is a configured setting on Google Ads, it can include or exclude whatever actions you’ve chosen. Meta’s action fields are specific and explicit. Before blending, confirm both platforms are actually counting the same business event, a purchase compared against a purchase, not a purchase compared against a broader “conversion” that also includes leads or sign-ups.

Ready-made templates

If you’d rather start from a template than build the report from scratch:

FAQs

Why don't my blended numbers match what I see in each platform separately?

Usually a date-grain, currency, or conversion-definition mismatch, see the three common issues above. Pin both platforms to the same explicit date range and confirm you’re comparing the same conversion event before blending.

Should I use blended ROAS or platform-level ROAS?

Both, for different questions. Blended ROAS tells you whether your total ad spend is working. Platform-level ROAS tells you which platform is more efficient with the budget it has.

Does this work the same in ChatGPT, Claude, and Copilot?

Yes. Once both Meta Ads and Google Ads are connected to Windsor.ai, the same blended pull and prompt works in any of the three.