AI Reasoning Token Cost Calculator

Reasoning models think before they answer. That thinking is a stream of reasoning tokens (OpenAI's term), thinking tokens (Anthropic, Google) that the model generates internally. You usually never see them — the API discards or summarises the trace — but every provider counts and bills them, and crucially they are billed at the model's output rate, not the cheaper input rate.

A naive cost estimate prices only what you can point at: the prompt you sent and the answer you received. The real bill adds a third, invisible line. The calculator above uses this model:

1. Convert the published per-million rates to per-token prices: Pin = input$/1M ÷ 1,000,000 and Pout = output$/1M ÷ 1,000,000.
2. inputCost = inputTokens × Pin
3. reasonCost = reasoningTokens × Pout — the hidden cost.
4. outputCost = visibleTokens × Pout
5. costPerCall = inputCost + reasonCost + outputCost, while naivePerCall = inputCost + outputCost. The multiplier is their ratio, and the monthly figure is costPerCall × callsPerMonth.

Because reasoning tokens and visible tokens are both billed at Pout, the per-call cost can also be written inputCost + (reasoning + visible) × Pout. The tool computes the cost both ways and they agree to the cent — a built-in cross-check on the math. Effort levels (Low, Medium, High, Max) seed a typical reasoning-token estimate; reasoning counts are non-deterministic, so the field is editable and the methodology is a planning aid, not a guarantee. For an exact figure, read your real reasoning_tokens value from the API response.

• Anthropic — Pricing (base input/output rates)
• Anthropic — Extended thinking (thinking tokens billed as output)
• OpenAI — API pricing
• OpenAI — Reasoning guide (reasoning_tokens billed as output)
• Google — Gemini API pricing
• Google — Gemini thinking (thinking output billing)

Anthropic rates were cross-checked against the Anthropic pricing page on 2026-06-06. OpenAI and Gemini rows are published list prices that change without notice — re-check them against the linked source before relying on a figure. No live API calls are made; pricing is a static, dated table.