Core Web Vitals Mobile Calculator

Audit mobile speed using weighted vital scorecards. Review thresholds, grades, trends, and action-ready recommendations instantly. Download clean reports and compare sample results before deployment.

Calculator Inputs

Enter mobile field or lab values, then calculate an overall mobile readiness score.

Use measured values from PageSpeed, CrUX, Lighthouse, WebPageTest, or your own RUM dashboard.
Optional. Use this to label the report and downloads.

Core and supporting metrics

Largest Contentful Paint.
Interaction to Next Paint.
Cumulative Layout Shift.
First Contentful Paint.
Time to First Byte.
Visual completion speed.
Total Blocking Time.
Total transferred page size.
Total network requests.
Downloaded JavaScript size.
Transferred image size.
Ads, analytics, chat, widgets, and embeds.
Render-blocking files on load.
Static assets served with cache policy.
Eligible text assets using Brotli or Gzip.

Delivery and optimization options

Above-the-fold styles prioritized.
Images and iframes delayed below the fold.
Static assets delivered from edge nodes.
WebP or AVIF served when possible.
Prevents invisible text on mobile.

Formula Used

Primary Metric Score
Each metric is normalized to a 0 to 100 score. Lower values score better. Good thresholds score 100. Poor thresholds score 0. Values between them are linearly interpolated.
Primary Weighted Score
Primary Score = (LCP × 28%) + (INP × 24%) + (CLS × 20%) + (FCP × 10%) + (TTFB × 8%) + (Speed Index × 6%) + (TBT × 4%)
Architecture Score
Supporting delivery factors are also scored from 0 to 100. Lower payload, fewer requests, fewer blockers, better cache coverage, and stronger compression raise the score.
Final Score
Overall Score = (Primary Score × 0.80) + (Architecture Score × 0.20)
This calculator is meant for mobile page analysis. Treat inputs as mobile measurements, ideally from field data or repeated lab tests.

How to Use This Calculator

  1. Collect mobile values for LCP, INP, CLS, FCP, TTFB, Speed Index, and TBT from your preferred performance tool.
  2. Enter supporting inputs such as page weight, requests, JavaScript payload, image payload, and third-party calls.
  3. Mark the delivery options that are already implemented, such as CDN use, lazy loading, or modern image formats.
  4. Click the calculate button to generate the score, grade, metric statuses, graph, and priority recommendations.
  5. Download CSV for raw values and PDF for a clean shareable report.
  6. Use the output to identify whether the main problem is interactivity, loading, layout stability, or delivery overhead.

Example Data Table

Sample Page LCP (s) INP (ms) CLS FCP (s) TTFB (s) Speed Index (s) TBT (ms) Weight (KB) Requests
Homepage 2.10 170 0.06 1.50 0.62 2.90 150 1320 46
Category Page 2.95 230 0.09 2.00 0.88 4.20 260 1760 69
Blog Post 3.70 310 0.18 2.60 1.20 5.30 420 2480 102

Frequently Asked Questions

1. What does this calculator measure?

It estimates mobile page health using Core Web Vitals, supporting performance metrics, and delivery factors like payload size, requests, caching, and compression.

2. Is the score a direct search ranking score?

No. It is a decision-support score for technical review. It helps prioritize fixes, but it does not represent an official search ranking formula.

3. Should I use field data or lab data?

Field data is better for real user experience. Lab data is still useful for debugging, testing templates, and tracking changes before deployment.

4. Why are LCP, INP, and CLS weighted more heavily?

They are the main Core Web Vitals. The calculator gives them more influence because they represent loading, responsiveness, and visual stability.

5. Why include page weight and request count?

Heavy pages and high request counts often slow mobile loading. They also increase CPU work, network delay, and rendering pressure.

6. Can this calculator compare multiple URLs?

Yes. Run it once per page, save the CSV outputs, and compare the scores, metric statuses, and top priorities across templates.

7. What score should I target?

Aim for 90 or above while also passing LCP, INP, and CLS. A high score without a CWV pass still needs attention.

8. What is the fastest way to improve poor mobile results?

Start with the metric causing the worst score, then reduce JavaScript, optimize images, improve caching, and remove blocking resources.

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.