GA4 vs Sealmetrics
Google Analytics 4 and Sealmetrics take fundamentally different approaches to web analytics. GA4 relies on cookies and user consent. Sealmetrics uses consentless, privacy-preserving tracking that captures 100% of traffic without cookies or consent banners.
This comparison covers the core differences across data accuracy, privacy compliance, features, implementation, and pricing.
The Core Problem: Consent-Based Data Loss
GA4 depends on cookies to identify users and track sessions. Under GDPR, visitors must consent before GA4 can set cookies. When they refuse — or simply ignore the banner — GA4 records nothing.
Industry data shows rejection rates vary significantly by country:
| Country | Estimated cookie rejection rate |
|---|---|
| Germany | 70–87% |
| France | 60–73% |
| Netherlands | 55–65% |
| Spain | 40–55% |
| United Kingdom | 35–50% |
Rates vary by industry, banner design, and implementation. Sources: CNIL annual reports, Eurostat digital economy surveys, CMP vendor benchmarks.
Result: rejection is not the same as data loss — some visitors accept, and Consent Mode models part of the rest — but in practice GA4 loses 15–60% of EU visitor data, depending on sector, brand strength and traffic mix. Branded direct traffic consents at a very different rate from cold paid social. Sealmetrics captures 100% because it never requires consent — no cookies are set, and no personal data is collected.
Feature Comparison
Data Collection
| Feature | GA4 | Sealmetrics |
|---|---|---|
| Tracking method | Cookies + client ID | Cookieless session + isolated hits |
| Consent required | Yes (GDPR) | No |
| Data capture rate (EU) | 40–85% (15–60% lost to consent) | 100% |
| Cookie banners needed | Yes | No |
| IP address storage | Yes (processed) | No (never stored) |
| Cross-site tracking | Yes | No |
| Ad blocker resistance | Low (blocked by most) | High (first-party setup) |
Reporting & Analytics
| Feature | GA4 | Sealmetrics |
|---|---|---|
| Real-time dashboard | Yes | Yes |
| Traffic sources & UTM | Yes | Yes |
| Conversion tracking | Yes | Yes |
| Funnel analysis | Yes (Explorations) | Yes (built-in) |
| E-commerce tracking | Yes | Yes |
| Geographic reports | Yes | Yes (country-level) |
| Device & browser reports | Yes | Yes |
| Custom events | Yes | Yes |
| Content grouping | Yes | Yes |
| AI insights | Limited | LENS AI (ask your data in plain language) |
| Unique visitors | Yes | No (requires individual tracking) |
| Bounce rate | Yes | Yes (aggregate-only, no individual tracking) |
| Session duration | Yes | No (requires individual tracking) |
Why some metrics differ: Metrics that require identifying and following individual users across page loads (unique visitors, session duration, individual user journeys) constitute personal data processing under GDPR — Sealmetrics deliberately excludes them. Bounce rate is not one of them: Sealmetrics computes it in aggregate as (Entrances − Engaged Entrances) / Entrances × 100, where "engaged" means a session with more than one pageview. No personal identifier is needed. Sealmetrics also exposes entrances, engaged entrances, and pages per session as additional privacy-safe traffic-quality signals.
Privacy & Compliance
| Feature | GA4 | Sealmetrics |
|---|---|---|
| GDPR compliant without consent | No | Yes |
| ePrivacy Directive compliant | Requires consent | Yes |
| Meets CNIL criteria for analytics sans consentement | No | Yes (self-assessment) |
| Meets AEPD audience-measurement criteria | No | Yes (self-assessed) |
| UK PECR compliant | Requires consent | Yes |
| Data hosting | US (Google Cloud) | EU only (Dublin, Ireland) |
| Sub-processors | Multiple (Google) | Short list — visitor analytics data processed only in the EU (see list) |
| Data sharing with third parties | Yes (Google Ads, etc.) | No |
| International transfers of analytics data | Yes (US) | No |
| Schrems II compliant | Requires SCCs/DPF | Yes (EU-only analytics processing) |
Technical Specifications
| Spec | GA4 (gtag.js) | Sealmetrics |
|---|---|---|
| Script size (gzipped) | ~146 KB | 1.1 KB |
| Cookies set | 6+ (_ga, _gid, etc.) | 0 |
| localStorage usage | Yes | No |
| Page load impact | High (render-blocking) | Minimal (defer, async) |
| SPA support | Yes (manual config) | Yes (automatic detection) |
| Server-side tracking | Yes (GA4 MP) | Yes (API) |
Data Accuracy: A Practical Example
Consider an e-commerce site with 100,000 monthly visitors in an EU market, losing 60% of its analytics data to consent — the high end of the range, typical of a site with weak brand recognition running mostly cold paid traffic.
| Metric | GA4 reports | Sealmetrics reports | Difference |
|---|---|---|---|
| Visitors tracked | ~40,000 | 100,000 | 2.5x more |
| Conversions tracked | ~400 | 1,000 (1% of 100K actual) | 2.5x more |
| Revenue attributed | €40,000 | €100,000 | €60,000 missing in GA4 |
| Traffic sources accurate | Partial (consent bias) | Complete | GA4 over-reports "Direct" |
A strong consumer brand whose visitors mostly arrive direct would sit nearer the 15% end, and the gap would be correspondingly smaller.
The consent bias problem: the shortfall is not evenly distributed. Visitors who accept cookies tend to be more engaged, so what is left is a skewed sample, not a smaller random one — GA4's data does not just have fewer rows, it over-represents your most engaged visitors. That biases exactly the comparisons budget decisions rest on.
Direct Traffic Inflation in GA4
One of the most common data discrepancies between GA4 and Sealmetrics is inflated "Direct" traffic in GA4.
Why it happens:
- A visitor arrives from a Google Ads campaign
- GA4 shows a consent banner
- The visitor rejects cookies
- GA4 cannot read UTM parameters or set attribution cookies
- The visit is classified as "Direct / (none)"
Sealmetrics reads UTM parameters from the URL on every page load without cookies, so attribution works regardless of consent status. This means campaigns, referrals, and organic search traffic are attributed correctly 100% of the time.
When to Use GA4
GA4 may still be the better choice if you:
- Need Google Ads integration with automated bidding and audience sync
- Require user-level analysis (individual user journeys, cohort analysis)
- Operate primarily outside the EU where cookie rejection rates are lower
- Need predictive metrics (purchase probability, churn probability)
- Already invested heavily in BigQuery + GA4 pipelines
Many teams use GA4 and Sealmetrics together — GA4 for Google Ads optimization (with consented users) and Sealmetrics as the source of truth for total traffic and conversions.
When to Use Sealmetrics
Sealmetrics is the better choice if you:
- Need accurate data across all EU markets
- Want to remove cookie banners or reduce consent friction
- Want to measure without processing personal data, so GDPR, CNIL and AEPD questions about analytics have a short answer
- Want 100% conversion attribution for budget decisions
- Need a lightweight tracker that does not slow down your site
- Want an AI assistant on your own data (LENS) out of the box
- Require EU-only data hosting with no international transfers
Pricing Comparison
| GA4 (Free) | GA4 360 | Sealmetrics Growth | Sealmetrics Scale | |
|---|---|---|---|---|
| Monthly cost | Free | ~€12,500/mo | €599/mo (€499 annual) | €1,079/mo (€899 annual) |
| Events included | 10M/mo | 25B/mo | 5M/mo | 15M/mo |
| Data retention | 14 months | 50 months | 24 months | 24 months |
| Consent required | Yes | Yes | No | No |
| Overage charges | N/A | Custom | None | None |
| Support | Community | Dedicated | Email + Chat | Priority |
| Data hosting | US | US | EU | EU |
GA4 Free is technically free but carries hidden costs: CMP platforms (€100-500/mo), legal reviews, lost revenue from missing data, and engineering time for Consent Mode implementation.
See full plan details for all Sealmetrics tiers.
Migration: GA4 to Sealmetrics
Switching from GA4 to Sealmetrics takes minutes, not weeks:
- Add the Sealmetrics tracker — one script tag (installation guide)
- Configure conversions — map your GA4 events to Sealmetrics conversions
- Set up UTM parameters — Sealmetrics reads standard UTMs automatically
- Run both in parallel — keep GA4 running alongside Sealmetrics to compare data
- Remove GA4 when you are confident in the data
You do not need to migrate historical data. Sealmetrics starts collecting from day one, and within 30 days you will have enough data for meaningful comparison.
For platform-specific guides, see our integration docs for WordPress, WooCommerce, Shopify, Magento, Next.js, and more.
Frequently Asked Questions
Can I use GA4 and Sealmetrics at the same time?
Yes. Many customers run both during a transition period. Sealmetrics does not interfere with GA4, and the 1.1 KB script adds negligible load. Running both lets you verify data differences firsthand.
Does Sealmetrics integrate with Google Ads?
Sealmetrics tracks Google Ads campaigns via UTM parameters and provides ROAS reporting. However, it does not sync audiences back to Google Ads for automated bidding — that requires GA4 with consented user data.
Is Sealmetrics data less detailed than GA4?
Sealmetrics intentionally does not track unique visitors, session duration, or individual user journeys because doing so requires personal data and consent. Bounce rate is calculated — in aggregate, using entrances vs engaged entrances, without any individual tracking. For aggregate traffic analysis, conversion tracking, attribution, and campaign performance, Sealmetrics provides equal or better accuracy since it captures 100% of traffic.
What about Google Consent Mode v2?
Google Consent Mode v2 uses statistical modeling to estimate conversions from users who reject consent. These are modeled estimates, not actual measurements. Sealmetrics captures real data from every visitor without modeling or estimation.
How does Sealmetrics handle bot traffic?
Sealmetrics includes built-in bot detection that filters automated traffic, crawlers, and known bot signatures. This ensures your data reflects real human visitors.
Summary
| GA4 | Sealmetrics | |
|---|---|---|
| Best for | Google Ads optimization, user-level analysis | Accurate total traffic, privacy compliance |
| Data accuracy (EU) | 40–85% of traffic | 100% of traffic |
| Consent required | Yes | No |
| Privacy exposure | Personal data processed, transferred to the US | No personal data processed, EU-only storage |
| Script size | ~146 KB | 1.1 KB |
| Pricing | Free (with hidden costs) | From €499/mo (annual billing) |
The question is not whether GA4 or Sealmetrics has more features. The question is whether you can make business decisions while 15–60% of your actual data is missing.
Related reading:
- Sealmetrics vs Google Analytics: Complete Comparison — In-depth blog post with real-world data examples
- Sealmetrics vs Plausible — How Sealmetrics compares to another privacy-first alternative
- Cookie Banner Ghosting — why visitors who ignore the banner are the largest missing group
Need help deciding? Contact us at support@sealmetrics.com or start a free trial.