Why would AdSense page views suddenly double while page RPM drops by about half?

A near-doubling of page views can cut Page RPM roughly in half if estimated earnings didn’t rise with it. That’s just the AdSense formula: estimated earnings divided by page views, times 1,000. So the RPM drop is probably the symptom, not a separate pricing problem. The thing to investigate is why AdSense started counting more page views: compare the exact hour the change began with your analytics and server logs, then review recent traffic-source, template, redirect, and navigation changes. If the spike looks artificial or comes from an unfamiliar source, review it promptly; Google treats artificially inflated impressions or clicks as invalid traffic. Don’t make ad-layout changes just to chase the RPM until you know whether the extra page views were real visitor page loads.