Core Web Vitals Conversion Impact

Forecast the revenue lift from Core Web Vitals projects by pairing the before/after metrics with elasticity coefficients from case studies and Google research.

Average number of visits or sessions affected by the improvement.
Current conversion rate before Core Web Vitals improvements.
Original Web Vital value (e.g., LCP in milliseconds).
Improved Web Vital value after optimisation.
Optional. Defaults to 0.18 if blank (conversion gain per log change).
Optional. Defaults to $0 if blank.
Optional. Defaults to $0 if blank to compute payback.

For growth modelling only—validate assumptions with experimentation and analytics before committing budgets.

Examples

  • 85,000 sessions, 2.8% CR, LCP 4,200→2,500 ms, elasticity 0.18, $170 AOV ⇒ Conversion uplift: 9.34%; +$37,783/month
  • 120,000 sessions, 4.0% CR, INP 380→200 ms, elasticity 0.10, $120 AOV, $78k cost ⇒ Payback 2.1 months

FAQ

Where do the elasticity coefficients come from?

Use published studies or your A/B test history—Google, Deloitte, and Akamai often cite elasticities between 0.08 and 0.25 depending on industry.

Can I model negative outcomes?

Yes—if performance regresses (after > before), the log ratio becomes negative and the tool outputs a conversion decline.

How do I incorporate multiple Web Vitals?

Run the calculator separately for LCP, INP, and CLS improvements, then combine the incremental conversions in your forecast spreadsheet.

Does this replace experimentation?

No—treat it as a directional model. Validate gains with controlled experiments or observe conversion trends post-launch.

Additional Information

  • Elasticity represents the percentage conversion change for each natural log change in the Web Vital—adjust it using your own test data.
  • Enter metric values in the same unit (ms or seconds) so the log ratio reflects proportional improvement.
  • Add a project cost to convert monthly revenue gains into an estimated payback period for stakeholder buy-in.

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