Definition
GCLID is a click identifier Google Ads appends to landing page URLs to help attribute sessions and conversions back to ads.
How to use it
- Store GCLID on click and pass it to your conversion system (CRM, offline conversions) when needed.
- Treat GCLID as an attribution aid, not a guarantee (privacy and cross-device still matter).
- Use consistent UTMs alongside GCLID for readable reporting.
Common mistakes
- Dropping the click ID on redirects or cross-domain hops.
- Relying on click IDs without validating conversion deduplication.
Why this matters
This term matters because it affects how you interpret performance and make budget decisions. If you use inconsistent definitions or windows, ROAS/CPA can look "better" while profit gets worse.
Practical checklist
- Write a 1-line definition for "GCLID (Google Click ID)" that your team will use consistently.
- Keep the time window consistent (weekly/monthly/quarterly) when comparing trends.
- Segment results (channel/plan/cohort) before drawing big conclusions from blended averages.
- Sanity-check with a related calculator from the same category on MetricKit.
- Read the related guide (e.g., UTM + GA4 attribution: practical tracking for paid ads (without lying to yourself)) for context and common pitfalls.
Where to use this on MetricKit
Calculators
- Break-even CTR Calculator: Compute the CTR required to break even (and hit a target) given CPM, CVR, AOV, and contribution margin.
- A/B Test Sample Size Calculator: Estimate sample size per variant for a conversion rate A/B test given baseline CVR, MDE, significance, and power.
- CPL to CAC Calculator: Convert cost per lead (CPL) into CAC using lead-to-customer rate (and compute targets).
- Break-even CVR Calculator: Compute the CVR required to break even (and hit a target) given CPM, CTR, AOV, and contribution margin.
- Click-through Conversion Rate Calculator: Calculate click-through conversion rate (click-to-conversion CVR) and estimate required clicks for target conversions.
Guides
- UTM + GA4 attribution: practical tracking for paid ads (without lying to yourself): A practical guide to UTMs and GA4: consistent source/medium/campaign tagging, conversion deduplication, and common attribution traps.
- Attribution vs incrementality: what to trust, when, and how to test: A practical guide to attribution vs incrementality: common attribution models, window pitfalls, how MER/marginal ROAS fit in, and how to run holdout/geo tests.