A good GTmetrix grade is an A or B. The grade is a letter from A (best) to F (worst), worked out by combining your Performance score and your Structure score into one percentage. Treat the grade as a quick summary, and use Core Web Vitals from real visitors as the real measure of speed. You can cross-check your page with our free website speed test.
Key takeaways
- The GTmetrix grade combines two scores: Performance and Structure.
- The Performance score is based on Lighthouse, the same engine behind Google PageSpeed Insights.
- The Structure score checks how well the page is built for speed.
- A or B is a sensible target, though a high grade does not guarantee passing Core Web Vitals.
What is the GTmetrix grade?
The GTmetrix grade is a letter grade that summarizes how fast and well built a page is. GTmetrix combines the Performance score and the Structure score into one percentage and converts it to a letter. For example, a combined result between 70% and 79% earns a C.
How is the GTmetrix grade calculated?
| Score | What it measures |
|---|---|
| Performance | The Lighthouse performance score measured in GTmetrix’s test environment, covering loading and responsiveness metrics |
| Structure | A GTmetrix score for how well the page is built for speed, based on a set of audits |
GTmetrix has described the grade as a weighted combination of the two scores. Because the exact weighting has been described differently over time, check the current GTmetrix documentation if you need the precise figures.
What is the difference between Performance and Structure score?
The Performance score is the stopwatch: it measures how quickly the page loads and becomes usable. The Structure score is the checklist: it shows whether the page follows good practice, such as compressed images and efficient caching. Improving the Structure audits usually improves the Performance score too.
What is a good GTmetrix grade?
An A or B is a good grade for most sites. A C means there is clear room to improve, and anything lower points to larger problems. This is a practical guideline, not an official Google standard. A perfect result is not needed, and chasing it gives little extra benefit.
Is the GTmetrix grade the same as the PageSpeed Insights score?
No. The Performance part is based on Lighthouse, as is PageSpeed Insights, but GTmetrix tests from its own locations with its own settings and then adds the Structure score. That is why the two tools show different numbers. For score ranges on Google’s side, see what a good PageSpeed score is, and read GTmetrix alternatives if you want a second tool.
How do you improve your GTmetrix grade?
- Open the Structure tab and fix the failing audits with the biggest impact.
- Compress and resize images. See how to optimize images for page speed.
- Enable caching and compression on your server.
- Defer or remove unused JavaScript and CSS.
- Cut third-party scripts you do not need.
- Test again two or three times and compare the pattern.
For the full list, read our guide on how to improve website speed.
Frequently asked questions
Is a GTmetrix grade of B good?
Yes, a B is a good result for most sites. Check Core Web Vitals as well, because a good grade does not guarantee you pass them.
Does the GTmetrix grade affect SEO?
Not directly. Google does not use the GTmetrix grade. It uses Core Web Vitals from real visitors as part of its page experience signals.
Why is my GTmetrix grade different each time?
Lab results vary with server response, network conditions and test settings. Small changes are normal, so test more than once.
Why is my GTmetrix score lower than PageSpeed Insights?
The tools use different test locations, devices and connection settings, and GTmetrix adds the Structure score. Compare results from the same tool over time.
Is there a free alternative to GTmetrix?
Yes. You can use Google PageSpeed Insights, WebPageTest or our free page speed checker.
Conclusion
A good GTmetrix grade is an A or B, built from your Performance and Structure scores. Use it as a quick health check, fix the failing Structure audits first and confirm real-world speed with Core Web Vitals. Run a second opinion on your page with our free website speed test.
