The cost formula (the part with two streams)
Every Sonar API call adds two streams together. There is no platform fee, no minimum spend, no per-seat charge — but you absolutely cannot model your bill with the OpenAI-style token-only formula. The right shape:
``` cost = (input_tokens / 1,000,000) × input_price_per_M + (output_tokens / 1,000,000) × output_price_per_M + (requests / 1,000) × per_request_fee_per_1K ```
On Sonar (the entry tier), a 1,000-in / 500-out call with a medium-depth search at the $8/1K request rate bills as: $0.001 (input) + $0.0005 (output) + $0.008 (one search) = $0.0095 per call. The per-request fee is 84% of the total. On Sonar Pro the token side is bigger, but the per-request fee is still the line item that surprises teams who modeled the bill in a spreadsheet copied from an OpenAI calculator.
Sonar Reasoning Pro folds the search fee into the token price — useful when you want a predictable per-call cost or when the workload runs many shallow searches that would otherwise stack request fees. Sonar Deep Research adds a third stream: citation and reasoning tokens, billed separately and often dwarfing the prompt/answer tokens themselves on a long-form research run.