Gartner: worldwide AI-optimized IaaS spending 2026 — $42.3B (+96% YoY from $21.5B), with inference ($23.3B) overtaking training ($19B) for the first time; inference = 55% of this spend in 2026, forecast 59% in 2027. Cloud IaaS dollars, not fleet MW — complements, does not replace, the ~2/3-of-compute figure

$42.3B; inference $23.3B > training $19Bforecast

Where the guide uses it

• 1.3 Inference Data Centers: Bursty, Distributed, Always-On

← Full numbers register — every date-stamped figure in the guide, with revision history.