Issue
I want to know why some Web Vitals are missing on the Web Vitals page, how Performance Score is calculated, what the score thresholds mean, and why Sentry’s scores can differ from other tools.
Applies To
All SaaS Customers
Web Vitals / Tracing
Resolution
Web Vitals are measured in the user’s browser and collected by the Sentry browser SDK when available. Not every browser reports every vital, so some fields may be empty. See browser support.
Performance Score is a 0–100 rating of perceived page performance based on those vitals:
Each available Web Vital is scored from 0–100 using a log-normal distribution.
Each vital’s score is multiplied by a weight. For example, LCP and INP are weighted more heavily than CLS.
The weighted scores are combined into one Performance Score, with a maximum of 100.
If a page load is missing some vitals, Sentry redistributes the weights across the vitals that are available. Default weights and Good / Meh thresholds are listed in Performance Score.
Sentry’s scores can differ from Lighthouse or other tools because Sentry uses real-user (RUM) data, its own weights and distributions, and only the vitals available for that load. Use Opportunity on the Web Vitals dashboard to see which pages would have the biggest impact on the overall score if improved to 100.
For pages that never appear in Web Vitals, see Why are some transactions not showing up in Web Vitals?