CrUX vs your own speed tracking (RUM)

CrUX vs your own speed tracking (RUM)

CrUX (Chrome User Experience Report) is Google's free field data, but it only counts Chrome users, updates monthly, and rolls 28 days together. RUM (Real User Monitoring — a script you add to measure every visit) is your own data, instant and complete.

Think of CrUX like a monthly weather summary, and RUM like a thermometer on your porch.

When each one wins:
— Diagnosing what you ship right now: RUM, because you see today's numbers, not last month's blur.
— Matching what Google uses for ranking: CrUX, since that's literally their source.

Try this: if you have no budget, lean on CrUX. If you can add one small script, try a free RUM tool like the web-vitals JavaScript library. Start tiny, watch one metric. You don't need both on day one.