Introductory rates: $0.75/M input, $3.75/M output through Dec 31, 2026. Both double to $1.50/$7.50 on Jan 1, 2027.
Predecessor pricing: Google applied the same promo rate to 3.6 Flash, so both models cost the same during the window. Migration becomes a capability decision, not a cost one.
Thinking tokens count as output. 3.7 Flash offers three reasoning levels (low, medium, high); higher settings increase output volume substantially, pushing agent-loop costs well beyond headline input pricing.
Promotional windows aren't synchronized. Claude Sonnet 5's introductory pricing expired Aug 31. Gemini's runs through Dec 31. GPT-5.6 Luna lists lower base rates without a published expiration. Teams choosing providers during one window may face different economics when another closes.
Cost per task vs. cost per token. For agent workflows, the meaningful unit is cost per completed task, including retries, tool calls, evaluation loops, and recovery. Token price is one input to that calculation.