LCP Budget Calculator

Summary

Enter your measured or target LCP value and instantly see how it rates against Core Web Vitals thresholds — Good, Needs Improvement, or Poor.

How it works

1. Enter your current or measured LCP value in milliseconds or seconds.
2. The calculator normalizes your input and maps it to the three Core Web Vitals bands.
3. A color-coded result shows whether you are Good, Needs Improvement, or Poor.
4. The budget gap section tells you exactly how many milliseconds you need to save to reach the next threshold.
5. The percentile context panel explains what score to target for the 75th-percentile user.
6. Copy the summary to share your performance budget with your team.

Use cases

• Set a measurable LCP performance budget before starting a project.
• Evaluate Lighthouse or CrUX field data against Core Web Vitals thresholds.
• Estimate how much render time you need to cut to reach a Good score.
• Communicate performance targets clearly to designers and stakeholders.
• Track LCP improvement week-over-week by comparing old vs. new values.
• Quickly sanity-check a synthetic test result from WebPageTest or Lighthouse.
• Prioritize optimization work by knowing exactly how far you are from each band.
• Audit multiple pages at once by repeating the calculation for each URL.

Frequently Asked Questions