Claude Opus 5 vs GPT-5.6 Sol: which flagship reasoning model is cheaper?
On raw price, GPT-5.6 Sol wins - cheaper on input, output, and cached input. Pick Opus 5 when Anthropic's tool-use ecosystem or instruction following matters more than the bill.
Same-tier flagship reasoning from Anthropic and OpenAI, with close but not identical pricing.
Claude Opus 5 and GPT-5.6 Sol are the two top-tier reasoning models from Anthropic and OpenAI's 2026 generation. Sol is the cheaper of the two on both input ($4 vs $5) and output ($20 vs $25), so on cost alone it wins. Opus 5 fights back on Anthropic's tooling ecosystem.
By TechCompare · Updated
Cost Comparison
Based on 100,000 input tokens (50% cached), 5,000 output tokens, and 100 requests.Prices are fetched live from OpenRouter and may include temporary promotional discounts not accounted for in our article and comparison figures.
Side-by-side specs
| Spec | Claude Opus 5 | GPT-5.6 Sol |
|---|---|---|
| Input Cost (per M) | $5.00 | $4.00 (better on this spec) |
| Output Cost (per M) | $25.00 | $20.00 (better on this spec) |
| Cached Input (per M) | $0.50 | $0.40 (better on this spec) |
| Batch Discount | 50% | 50% |
| Context Window | 1M | 1.05M (better on this spec) |
How they differ
Claude Opus 5 is priced at $5.00 per million input tokens and $25.00 per million output tokens, with a 90% caching discount ($0.50 per million) and a 50% batch discount. GPT-5.6 Sol is priced at $4.00 per million input tokens and $20.00 per million output tokens, also with a 90% caching discount ($0.40 per million) and a 50% batch discount. For a typical 100K input + 10K output request, Opus 5 costs $0.75 and Sol costs $0.60 - a $150K difference over a million calls. On capability, both target the same 'hardest reasoning tier' but lean on different strengths: Opus 5's long-context agentic tool use vs Sol's math and code synthesis.
Verdict
Sol wins all three priced rows: $4.00/M input versus $5.00, $20.00/M output versus $25.00, and $0.40/M cached input versus $0.50, with a 50% batch discount and near-tied context (1.05M versus 1M) on both. A representative 100K input + 10K output call costs $0.60 on Sol against $0.75 on Opus, roughly a $150K difference at a million calls. There's no mode where Opus 5 is cheaper - the decision realistically rests on Anthropic-vs-OpenAI tooling fit and which model handles the workload better.
Which should you pick?
Choose Claude Opus 5
Long-context agentic chains, tool-heavy automations, and Anthropic-flavored instruction following. Opus 5's 1M context and mature tool-use ecosystem pay off when you push the model hard.
Choose GPT-5.6 Sol
Cost-sensitive flagship reasoning, math-heavy scientific work, code synthesis, and pipelines where OpenAI's tooling ecosystem is already wired in. Sol is cheaper on every priced row.