How to read the gcd parameter in Google Consent Mode v2

You open your browser's developer tools, filter by g/collect and spot a long parameter: gcd=11r1r1r1r5. It doesn't look like the gcs=G111 you already know. It's the gcd parameter — the most complete diagnostic tool Consent Mode v2 offers, and the one that has replaced gcs as the primary reference since 2025.

What is the gcd parameter

gcd stands for Google Consent Data. Unlike gcs (which only encodes two permissions in 4 characters), gcd encodes all four Consent Mode v2 permissions along with how each state was reached: the default value, the user's update, or both.

The gcd is sent with every request to Google, whether Consent Mode is active or not. This makes it the most reliable signal for understanding what's happening with consent on your site.

The gcd format: what each position means

The gcd value is a string with a fixed format:

11{signal1}1{signal2}1{signal3}1{signal4}5

The 11 at the start and 1 between each signal are fixed separators (they don't change). The 5 at the end is a closing value. What matters are the letters in the 4 signal positions:

Position	Signal	What it controls
1	ad_storage	Advertising cookies (conversions, remarketing)
2	analytics_storage	Analytics cookies (GA4)
3	ad_user_data	Permission to send user data to Google
4	ad_personalization	Permission for personalization and remarketing

Each letter encodes the full trajectory of consent for that signal: what was declared by default and what the user decided afterward.

The 9 letter codes: the alphabet of consent

The letters aren't random. They follow an alphabetical pattern across two dimensions: what was declared by default (column) and what the user did afterward (row).

Group 1: l, m, n — No default recorded

Letter	Default	Update	Meaning
l	(none)	(none)	Consent Mode didn't set a default or update.
m	(none)	Denied	No default, user explicitly denied.
n	(none)	Granted	No default, user explicitly granted.

Group 2: p, q, r — Default denied (most common)

Letter	Default	Update	Meaning
p	Denied	(none)	Default denied, user hasn't decided yet.
q	Denied	Denied	Default denied, user confirmed denial.
r	Denied	Granted	Default denied, user granted afterward. ✅

Group 3: t, u, v — Default granted

Letter	Default	Update	Meaning
t	Granted	(none)	Default granted, no user update.
u	Granted	Denied	Default granted, user denied afterward.
v	Granted	Granted	Default granted, user confirmed grant.

Memory trick: within each group of 3 letters, the first is "no update", the second is "update to denied", the third is "update to granted".

Practical examples: how to read a gcd

Before the user interacts (advanced mode)

gcd=11p1p1p1p5

All 4 letters are p: default denied, no update. This is correct in advanced mode — tags load with a denied default state and send cookieless pings until the user decides.

User accepts everything

gcd=11r1r1r1r5

All 4 letters are r: default denied → update granted. This is the ideal flow when the user accepts all categories. Each signal went from denied to granted via the banner update.

User rejects everything

gcd=11q1q1q1q5

All 4 letters are q: default denied → update denied. The user explicitly rejected. Cookieless pings still travel (advanced mode), but without cookies.

Partial selection: analytics yes, advertising no

gcd=11q1r1q1r5

Position 1 (ad_storage): q — denied → denied. Position 2 (analytics_storage): r — denied → granted. Position 3 (ad_user_data): q — denied → denied. Position 4 (ad_personalization): r — denied → granted.

This means the user accepted analytics and data, but rejected advertising and personalization.

Default granted without update (incorrect configuration)

gcd=11t1t1t1t5

All 4 letters are t: default granted, no update. This indicates the default was declared as granted instead of denied — an implementation error. Advanced mode requires the default to be denied.

gcs vs gcd: why gcd is better

Aspect	gcs	gcd
Permissions	2 (ad_storage, analytics_storage)	4 (all Consent Mode v2 signals)
Detail	Final state only (granted/denied)	Full trajectory (default + update)
Sent	Only with Consent Mode active	Always, with or without Consent Mode
Debugging	Basic	Complete
Format	G1xy (3-4 chars)	11l1l1l1l5 (9 chars)

gcs is still useful for a quick read (G111 = everything granted), but when you need to debug why something isn't working, gcd tells you the full story: what was declared, what the user decided, and in what order.

How to verify in Chrome DevTools

1. Open Developer Tools (F12 or Cmd+Opt+I).
2. Go to the Network tab.
3. Filter by g/collect (GA4 requests) or doubleclick (Google Ads requests).
4. Click any request and look for the gcd parameter in the query string.
5. Decode the 4 letters using the table above.

What to look for

State	Expected gcd	What to verify
Page loaded, no decision yet	11p1p1p1p5	Defaults correct (denied)
Accepted everything	11r1r1r1r5	All 4 signals changed to granted
Rejected everything	11q1q1q1q5	All 4 signals stayed denied
Only accepted analytics	11q1r1q1r5	Mix of q and r per choice
Default set to granted	11t1t1t1t5	⚠️ Error: default must be denied
Missing 1 separators	Unexpected format	⚠️ Possible incorrect implementation

Common errors the gcd reveals

Default set to granted (t, u, v)

If you see letters from the t/u/v group, your Consent Mode snippet declares granted as the default value. This violates advanced mode: Google expects the default to be denied and the user to change it to granted via the banner.

Missing ad_user_data or ad_personalization

If positions 3 and 4 show l (no default recorded) while positions 1 and 2 show p or r, your CMP isn't declaring the mandatory permissions since March 2024. Google Ads disables ad personalization even if the user accepted.

Update never arrives (p persists after banner)

If after the user accepts the banner the letters remain p (default denied, no update), your CMP isn't firing gtag('consent', 'update', …). The banner shows it worked, but the signal never reaches Google.

Inconsistent letter mix

If you see a combination like r1p1r1p5 (some r, some p), it means some signals were updated and others weren't. This usually happens when the CMP maps banner categories to Consent Mode parameters incorrectly.

Why it matters

The gcd isn't just a technical detail — it's the proof that your implementation works:

• Compliance: demonstrates that the default is denied and that consent is only granted after an explicit choice, as required by the GDPR.
• Modeling: Google needs correct signals in all 4 positions to activate conversion modeling in GA4 and Google Ads.
• Diagnostics: instead of guessing why the numbers don't add up, you read directly what's happening in each request.
• Audit: a privacy officer or auditor can verify compliance by inspecting the gcd in network requests.

How Conma solves it

Conma declares all 4 permissions as denied by default, synchronously, before any Google tag runs. When the user decides, it updates the state in under 500 ms. The result in the Network tab:

gcd=11r1r1r1r5

All 4 signals show r (denied → granted): the complete, correct flow, ready for audit. If you need an implementation that always arrives in the right order, read our guide to comply with Google Consent Mode v2.