• to content
  • to footer
  • Features
  • Customers
  • Pricing
  • Resources
    • Blog
      Speed matters, what's new and/ or important?
    • About us
      The story behind our tooling, mission and mindset
    • GDPR & security
      Guaranteeing privacy is one of our top priorities
    • Help Center
      Need help or guidance? Take a look in our help center
    • Use cases
      Learn how others, and you can use RUMvision
    • Contact us
      Questions about our real user monitoring solution?
  • Free tools
    • UX score check
      A single score, based on your own users + your ranking compared to 20k+ sites
    • Web Vitals history
      Get Core Web Vitals data up to 6 months in the past, of any domain.
    • Return on Investment calculator
      Want to know how much ROI you can get investing in webperformance?
    • Check your competitors
      Get Core Web Vitals data of your competitors and be the fastest.
  • Log in
  • Sign up
  • Book demo
  • Monitoring
    • Getting Started
      • Account setup
      • Installing the snippet
      • No (metric) data
      • Adding pages
      • Invite users
      • Adding competitors
    • Dashboards
      • Introduction
      • Audience
      • Core Web Vitals
      • Metrics table
      • Geography
      • Technical
      • Competitors
      • Third parties
      • Baseline
    • Workflow
      • To-do's
      • Annotations
      • Conversations
    • Settings
      • Domain settings
      • Custom timing
      • Logs
    • Configure snippet
      • Introduction
      • - General
      • - Track and block
      • - Advanced
      • - RUM
      • Updates & new data
    • SPA & Soft Navs
      • Introduction
      • Customize SPA tracking
      • Detailed TTFB tracking
      • - NextJS
      • - NuxtJS
      • - Other frameworks
      • Analyzing the data
  • Filters
    • Introduction
      • Your start with filters
      • By subscription
    • Webpage
      • Page URL
      • Page template
      • Page language
    • Metric
      • Metric Element
      • Element text
      • Element Type
      • File Type
      • Lazy Loading
      • Image Priority
      • Resource hint (LCP)
      • Cached
      • LoAF
      • Back & forward cache
      • Load state
    • Browser
      • Viewport
      • Bot Name
      • Browser Name
      • Browser Version
      • In-app Browsing
      • Ad blocker status
    • User
      • Pageview type
      • Navigation type
      • Pageview count
      • Rage clicks
    • Geography
      • CDN location
      • Country
    • Server
      • HTTP request method
      • GET parameters
    • Connectivity
      • Effective bandwidth
      • Bandwidth category
      • Reduced data usage
    • Device
      • Device memory
      • Processors
      • Battery level
      • Pixel ratio
      • OS name
      • OS version
      • Model
  • Account
    • Registration
      • Creating an account
      • Registration errors
      • On invitation
      • Expire/pause account
      • Reset password
      • Existing domain
    • Subscription
      • Plans
      • Add-ons
      • Your usage
      • Manage pageviews
      • Upgrading
      • Cancellation
    • Invoices
      • Billing procedure
      • Payment
      • Download & share
      • Received invitation
      • Change recipient(s)
      • Change (credit) card
      • Retroactive invoicing
    • Profile
      • Introduction
      • Settings
      • Dashboard
      • Theme
      • Apps
      • Notifications
      • Security
      • Two-factor authentication
      • Edit password
      • Logins
  • Workflow
    • Reports
      • Intro
      • Subscribe
      • Dashboard
      • Report history
    • Alerts
      • Intro
      • Budgets
      • Video tutorial
    • Your first alerts
      • Where to find alerts
      • Import preset alerts
      • Alerts overview
    • Customize alerts
      • Create your own alert
      • Subscribed users
    • Notifications
      • Enable notifications
      • Example notifications
  • APIs
    • Apps
      • Installing an app
      • Apps and users
      • - Discord
      • - MS Teams
      • - Slack
      • - Webhooks
      • - Zapier
      • Build your own
    • JS API
      • Introduction
      • Get and set
      • Config
      • CWV metrics
      • Custom dimensions
      • Custom timing
      • Functions
      • Debugging
    • API Client
      • Introduction
  • Releases
    • Changelog
      • Monitoring
      • Application
      • Web vitals library
      • JS API
      • Client API
    • Roadmap
      • In progress
      • Planned
    • Maintenance
      • Incidents
      • Scheduled
  • Privacy & security
    • Application
      • PII data
      • Account security
      • Domain security
      • Accountability
      • Verify with password
    • Monitoring
      • JavaScript integrity
      • PII data
      • Privacy by default
      • Anonymizing data
      • User country data
      • Browser & UA
      • Other data
    • Website
      • Privacy policy
  • Glossary
    • Monitoring
      • Core Web Vitals
      • PageSpeed Insights
      • Google Search Console
      • CrUX API
      • Real User Monitoring
      • Synthetic monitoring
      • - Lighthouse
      • - Webpagetest
    • Metrics
      • Web Vitals
      • - TTFB
      • - FCP
      • - LCP
      • - CLS
      • - INP
      • - FID
      • Field data
      • - FMP
      • - DCL
      • Lab data
      • - TTI
      • - TBT
      • - SpeedIndex
    • Browser
      • Chromium
      • Google Chrome
      • Origin trials
      • - Soft navigations
    • Dashboarding
      • 75th percentile
      • Aggregation
      • Distribution
      • Histogram
      • Timeline
    • Other
      • Low-entropy images
      • Page Experience ranking signal
      • Server-Side Rendering
      • Multi-Page Application
      • Client-side Rendering
      • Single Page Application
      • Progressive Web Apps
      • Accelerated Mobile Pages
  • Video tutorials
    • Getting started
      • Adding a domain
      • Installing the snippet
      • Configure your URLs
    • Dashboards
      • Competitors
      • Audience
      • Core Web Vitals
      • Metrics table
  • FAQ
    • General
      • Tracking
      • Data
      • Dashboard
      • Notifications
    • Pricing
    • Docs
    • Monitoring
    • Filters
    • Account
    • Workflow
    • APIs
    • Releases
    • Privacy & security
    1. Home
    2. Help Center
    3. Glossary
    4. Metrics
    5. SpeedIndex
    • Monitoring
      • Core Web Vitals
        • PageSpeed Insights
          • Google Search Console
            • CrUX API
              • Real User Monitoring
                • Synthetic monitoring
                  • • Lighthouse
                    • • Webpagetest
                    • Metrics
                      • Web Vitals
                        • • TTFB
                          • • FCP
                            • • LCP
                              • • CLS
                                • • INP
                                  • • FID
                                    • Field data
                                      • • FMP
                                        • • DCL
                                          • Lab data
                                            • • TTI
                                              • • TBT
                                                • • SpeedIndex
                                                • Browser
                                                  • Chromium
                                                    • Google Chrome
                                                      • Origin trials
                                                        • • Soft navigations
                                                        • Dashboarding
                                                          • 75th percentile
                                                            • Aggregation
                                                              • Distribution
                                                                • Histogram
                                                                  • Timeline
                                                                  • Other
                                                                    • Low-entropy images
                                                                      • Page Experience ranking signal
                                                                        • Server-Side Rendering
                                                                          • Multi-Page Application
                                                                            • Client-side Rendering
                                                                              • Single Page Application
                                                                                • Progressive Web Apps
                                                                                  • Accelerated Mobile Pages

                                                                                  SpeedIndex

                                                                                  This metric is only available in synthetic monitoring, WebPageTest being a good example here.

                                                                                  • PreviousTotal Blocking Time
                                                                                  • back to parent

                                                                                  With RUMvision, you can be sure your site is performing optimally

                                                                                  Discover how RUMvision helps your team to:

                                                                                  • Gain real-time insight into website performance
                                                                                  • Continuously improve user experience
                                                                                  • Create more conversions and satisfied visitors

                                                                                  Yes, book a free demo Start on your own

                                                                                  Product

                                                                                  • Features
                                                                                  • Customers
                                                                                  • Pricing
                                                                                  • Book free demo

                                                                                  Free tools

                                                                                  • Core Web Vitals UX score checker
                                                                                  • Core Web Vitals 6 month History
                                                                                  • Core Web Vitals compare 5 competitors
                                                                                  • Investing in Core Web Vitals ROI calculator

                                                                                  Resources

                                                                                  • About us
                                                                                  • Blog
                                                                                  • Use cases
                                                                                  • Help center
                                                                                  • Contact us

                                                                                  Subscribe to our Newsletter: RUMor has it

                                                                                  2025 All Rights Reserved © RUMvision, The Netherlands

                                                                                  • Sitemap
                                                                                  • Terms and conditions
                                                                                  • Privacy policy
                                                                                  • Accessibility

                                                                                  This website uses Google Analytics compliant to European privacy regulations, but wishes your approval for additional cookies to improve this website.

                                                                                  Settings Deny all Accept