Is Claude Sonnet 5.5 cheaper than GPT-6.1 Sol?

Not at list price — both charge $2 per million input tokens and $10 per million output tokens, making them identical for standard requests. The cost difference only appears with cached input (GPT-6.1 Sol is cheaper at $0.10/M vs $0.20/M) or very long prompts, where GPT-6.1 Sol applies a surcharge past 272K tokens.

What is the context window for each model?

Claude Sonnet 5.5 offers roughly a 1 million token context window, while GPT-6.1 Sol offers approximately 1.05 million tokens. Both are large enough for most long-document or long-conversation workloads, though GPT-6.1 Sol's pricing changes above 272K input tokens in a single request.

How much would 100M input and 30M output tokens cost per month?

At list prices, both models cost exactly $500/month for this workload: $200 from 100M input tokens (at $2/M) plus $300 from 30M output tokens (at $10/M). The totals are identical since both models share the same base input and output rates.

Are Claude Sonnet 5.5 and GPT-6.1 Sol both currently available?

Yes, both models are active and available via their respective provider APIs as of early October 2026. They launched within a day of each other in late September 2026 and remain current flagship-tier offerings from Anthropic and OpenAI respectively.

HEAD-TO-HEAD · FLAGSHIP-TIER · VERIFIED OCTOBER 3, 2026

Claude Sonnet 5.5 vs GPT-6.1 Sol: which is actually cheaper?

Claude Sonnet 5.5 and GPT-6.1 Sol launched a day apart and landed on an identical headline price: $2 per million input tokens and $10 per million output tokens. On paper, that makes this one of the rare true price ties in the flagship-tier market.

Spec	Claude Sonnet 5.5	GPT-6.1 Sol
Input / 1M tokens	$2.00	$2.00
Output / 1M tokens	$10.00	$10.00
Context window	1M	1.05M

The output price gap

There is no output price gap here — both models charge exactly $10 per million output tokens, and both charge $2 per million input tokens. For teams comparing sticker prices alone, this matchup is a wash; any real-world cost difference will come from secondary factors like cached-input rates and long-context surcharges rather than the base input/output rates themselves.

Context window

Claude Sonnet 5.5 ships with roughly a 1 million token context window, while GPT-6.1 Sol edges slightly ahead at approximately 1.05 million tokens. Both are large enough for most document-, codebase-, and long-conversation use cases, so the gap is unlikely to be a deciding factor for typical workloads — though GPT-6.1 Sol applies a surcharge (2x input, 1.5x output) once a single request passes 272K input tokens, whereas Sonnet 5.5 holds standard rates across its full window.

Worked example

At 100M input tokens and 30M output tokens in a month, the math is identical for both models at list price: input cost = 100M × $2/M = $200; output cost = 30M × $10/M = $300; total = $200 + $300 = $500/month for Claude Sonnet 5.5, and the same $200 + $300 = $500/month for GPT-6.1 Sol. At base rates, this workload costs exactly $500/month on either model — the tie-breaker for heavy, cache-light usage will come down to cached-input pricing (GPT-6.1 Sol's $0.10/M cache read vs Sonnet 5.5's $0.20/M) or long-context surcharges on large single requests.

Prices from the LLM Price Watch daily tracker, 2026-10-03. Prices change; use the calculator with your own usage for an exact comparison, or see the full price table for every tracked model.