Google Ads without cookies: conversions, remarketing and Smart Bidding with Consent Mode v2
Google Ads runs on conversion data. When a user rejects ad storage
(ad_storage), Google can no longer use cookies to measure and re-engage them.
The impact shows up on three fronts — measurement, audiences and automated bidding
— and each is cushioned differently.
1. Conversions: from exact data to modeling
Without ad_storage, Google Ads doesn't write conversion cookies, so it can't
accurately attribute which click drove which sale. Instead, it relies on
conversion modeling: it estimates the lost conversions from the behavior of
users who did consent and from aggregated click patterns.
Advertisers typically see a 15-25% uplift in reported conversions from modeling alone, versus sending no signal at all. It's the difference between a campaign that "looks" like it doesn't convert and one that proves its real return.
Example: if 60% of your European traffic rejects and you stop measuring those conversions, your apparent CPA spikes and you might pause profitable campaigns over a measurement problem, not a performance one.
2. Remarketing: audiences run dry
Remarketing depends on cookies to remember who visited your site. Without consent
for ad_storage and ad_personalization, that user doesn't enter your
remarketing lists. The effect is cumulative: every day without consent is a day of
audiences that don't grow.
The practical consequences:
- Smaller remarketing lists and, below Google's minimum, ones that can't even be used.
- Less effective re-engagement campaigns (abandoned cart, recent visitors).
- Lookalike audiences built on a poorer base.
3. Smart Bidding: worse fuel, worse bids
Automated bidding strategies (tCPA, tROAS, maximize conversions) learn from conversion data. If that data shrinks due to missing consent, the algorithm bids with less information, its learning phase drags on, and your efficiency drops. Conversion modeling feeds Smart Bidding again and helps stabilize performance — but only if the consent signals arrive correctly.
The 4 permissions you can't forget
Since the March 2024 update, keeping ad personalization in the EEA requires sending all four permissions, not just the storage ones:
| Permission | If missing… |
|---|---|
ad_storage | No measurement cookies or remarketing |
ad_user_data | User data can't be sent to Google |
ad_personalization | Remarketing and personalization are disabled |
analytics_storage | Affects conversion import from GA4 |
Sending only
ad_storageandanalytics_storage(the classics) is no longer enough: Google turns off personalization ifad_user_dataandad_personalizationare missing, even if the user accepted everything.
Reinforce the signal with first-party data
Modeling cushions the loss, but you can go further by recovering signal with consented first-party data:
- Enhanced Conversions: sends Google hashed data (email, phone) from users who did consent, to match conversions the cookie couldn't attribute.
- Server-side tagging: centralizes the sending, improves measurement durability and gives you more control over what's shared and when.
Both require honoring consent: they only apply to the traffic that accepted.
How to minimize the loss
- Use Consent Mode v2 in advanced mode to enable modeling.
- Ensure all 4 permissions travel with every measurement.
- Enable Enhanced Conversions and consider server-side tagging.
- Monitor the
gcs/gcdparameter to confirm signals arrive (how to read them).
What modeling can't recover
Modeling is powerful, but it's not magic, and it's worth managing expectations. Modeled conversions arrive at the campaign level, not the individual user, so you won't be able to re-engage whoever rejected through remarketing: that traffic is measured, but never re-targeted. It also doesn't fill very small segments or audiences below Google's minimum threshold. And it needs history: during the first weeks after enabling it, the estimates are still calibrating and you shouldn't jump to conclusions. That's why the correct order is to first maximize real consent — with a clear, honest, well-designed banner that doesn't push people toward rejecting — and then lean on modeling to cover the rest.
Conma guarantees all four permissions are declared and updated in the right order, so your Ads campaigns keep as much signal as legally possible.