How to Test Website Speed
“How fast is my website?” seems like a simple question, but honest tools answer a set of narrower ones: how quickly does the server respond, how many redirects does the page go through before loading, how long does a round trip take, and is anything about the setup obviously slow. This guide explains what different tools measure, what a browser can genuinely measure about another site, and how to avoid being misled by a single number.
Know what is being measured
There are at least five different things people call “website speed”:
- Server response time (TTFB) — how long until the first byte of the response arrives.
- Round-trip time (RTT) — how long a request takes to reach the server and come back.
- Load time — how long until the page is fully rendered in a specific browser.
- Throughput — how much data can move per second (measured by internet speed tests).
- Core Web Vitals — field metrics like LCP, INP and CLS, measured from real visitors.
These are related but not interchangeable. A site on a fast CDN with a slow backend can have a quick RTT and a slow TTFB. A connection speed test tells you about your network, not about the target site.
What a browser can measure about another site
Your browser is allowed to measure quite a lot just by making normal requests: the HTTP status, the redirect chain, response headers, DNS behavior, and (for requests it makes itself) network timing. It is not allowed to read another site’s live TLS certificate details, and browsers deliberately hide detailed timing of cross-origin resources unless the target sends a Timing-Allow-Origin header. That is why honest browser-based tools report TTFB as “not available” for most sites instead of estimating it.
Run the Website Speed Test correctly
Use the Website Speed Test like this:
- Enter the full URL, including
https://. - Run the test three times, at different times of day, and note the range.
- Read the report’s source labels: browser timings are yours; status and header checks come from the named server-side APIs.
- If the report says a measurement is “Not available in this test”, accept that. It is the honest answer, not a failure of the tool.
Read the Website Diagnostic Score with context
If you see a 0–100 score, check what it is actually made of. On YourAnalystAI, the score is computed only from the checks this page performed (HTTPS, HTTP status, redirects, round-trip time, DNS and content type), and the report lists every factor, its maximum weight and the measured value. It is this site’s own simplified summary — not a Google score and not a substitute for real field data.
Three honest comparisons
Useful tests to run, and how to compare:
- You vs. your previous version. Make one change, re-test under the same conditions, compare. This isolates the effect of your change.
- You vs. a direct competitor. Same network, same tool, back to back. Compare categories (server response, redirects), not just a single number.
- Desktop vs. mobile. Mobile network latency and weaker devices change results meaningfully.
Do not compare your small site against Google or YouTube. Their infrastructure is not a realistic benchmark for anything you control.
What to do with the results
Prioritize problems in this order: hard failures (5xx errors, broken HTTPS, huge redirect chains) first, then server response time, then asset issues (which the speed test can’t fully see, but the Core Web Vitals guide covers). Remember that speed gives an unfair advantage; results have a range, not a single truth.