Real ROAS vs Reported ROAS: Why Your Google Ads Numbers Lie (And How to Fix It)
Google Ads tells you ROAS 5. Your accountant tells you ROAS 2.8. The difference isn't minor: it's the difference between a profitable campaign and one that's losing money. This gap is systematic and has identifiable causes. This guide explains where it comes from and how to calculate your real ROAS.
Why Google Ads Reported ROAS Is Overestimated
ROAS displayed in Google Ads = (Tracked conversion value) / (Ad spend)
Each of these two elements can be biased:
**On the conversion value side:**
1. **Gross vs net value**: Google Ads tracks gross order value (with taxes, shipping). Your real margin is calculated on net value after returns and refunds.
2. **Multi-touch attribution**: with Last Click or Data-Driven, a conversion may be attributed to Google Ads even if the user was first influenced by Meta, email, or organic. Google Ads claims 100% of the credit.
3. **Assisted vs direct conversions**: assisted conversions (Google Ads contributed but isn't the last click) may be counted depending on your configuration.
4. **Secondary conversion values**: if you've configured micro-conversions (add to cart, page view, newsletter signup), make sure they're not counted in ROAS with a fictional value.
**On the spend side:**
5. **Costs not included**: agency fees, visual creation costs, tool subscriptions aren't included in reported Google Ads spend. Your real acquisition cost is higher.
6. **Spend timing**: Google Ads may spend with a delay relative to actual billing.
Calculating the Gap Between Reported and Real ROAS
**Calculation method:**
**Real ROAS = (Net revenue attributable to PPC campaigns) / (Total PPC campaign cost)**
Where: - Net revenue = Gross revenue - Returns - Refunds - Taxes - Total cost = Media spend + Agency fees + Creation costs + Tools
**Concrete example:**
Google Ads reports: - Conversion value: $50,000 - Spend: $10,000 - Reported ROAS: 5.0
Reality: - Customer returns: -$8,000 (16% return rate) - Taxes included in gross value: -$7,000 - Real net revenue: $35,000 - Agency fees: +$1,500 - Creative costs: +$500 - Real total cost: $12,000 - Real ROAS: $35,000 / $12,000 = **2.9**
Gap: 5.0 reported vs 2.9 real. The campaign is still profitable if your threshold is 2.5, but optimization decisions would be radically different.
Cross-Channel Attribution Biases
Multi-channel attribution is another source of gap. Your different channels often claim the same conversion.
**Triple counting example:** A user: 1. Sees a YouTube ad (impression) 2. Clicks on a Meta Ads ad 3 days later 3. Clicks on a branded Google Search ad and purchases
Google Ads Search counts: 1 conversion (ROAS = value / Search spend) Meta Ads counts: 1 conversion (within its 7-day click attribution window) YouTube Ads counts: potentially 1 assisted conversion
**If you add up the reported ROAS of all channels, you probably get 150-250% of your real revenue.**
**How to measure each channel's real contribution:**
1. **Blended View-Through Attribution**: look at ROAS after subtracting overlapping attributions. 2. **Incrementality testing**: turn off a channel for 2-4 weeks and measure the impact on total revenue. The difference = the channel's real increment. 3. **Marketing Mix Modeling (MMM)**: statistical modeling of each channel's impact on revenue. Requires 18-24 months of historical data. 4. **Last Non-Direct Click**: pragmatic attribution that credits the last non-direct channel before conversion. Undervalues YouTube and Display, but avoids branded bias.
The Monthly Reconciliation Dashboard
The practical solution: create a monthly reconciliation table between your Google Ads data and your real data.
**Recommended structure (Google Sheets):**
| Metric | Google Ads | Back-office / Accounting | Gap | % Gap | |---|---|---|---|---| | Number of orders | X | Y | X-Y | % | | Gross value | X | Y | X-Y | % | | Return rate | - | Z% | - | - | | Net value | - | Y*(1-Z%) | - | - | | Media spend | X | X | 0 | 0% | | Agency/tool fees | - | Z | - | - | | Gross ROAS | X/A | - | - | - | | Real net ROAS | - | Y*(1-Z%)/(X+Z) | - | - |
**Frequency:** monthly minimum, weekly if you're managing significant budgets.
**Tolerance rule:** a 5-10% gap between Google Ads conversions and your back-office is acceptable. Beyond that, there's probably a tracking issue to investigate.
Adjusting Your Targets Accordingly
If your real ROAS is systematically 40-50% lower than reported ROAS, you need to adjust your targets in Google Ads.
**Calibration example:** - Minimum profitable real ROAS: 2.5 - Average reported/real gap: 40% - Target ROAS in Google Ads: 2.5 / (1 - 0.40) = **4.2**
By setting a ROAS target of 4.2 in Google Ads tROAS, you get a real ROAS of 2.5 in practice, which is your break-even threshold.
**Note:** this calibration must be reviewed periodically (seasonality, change in return rate, agency fee modifications).
**The end goal:** have a dashboard where the ROAS you're piloting matches the ROAS your accountant confirms. That's rarely the case initially, but it's achievable with 2-3 months of reconciliation work.
Key Takeaways
- Reported ROAS from Google Ads is systematically overestimated: gross value, multi-touch attribution, excluded costs.
- Calculate real ROAS: (Net revenue after returns and taxes) / (Media spend + agency fees + tools).
- The sum of reported ROAS across all your channels often represents 150-250% of your real revenue.
- Create a monthly reconciliation table between Google Ads and your back-office/accounting.
- Calibrate your tROAS target in Google Ads accounting for the systematic gap to pilot on real ROAS.
This article is based on episode 0 of the podcast
Listen to the full version with Alexia and Maxence to dive even deeper.