GPT-5.6 vs Claude Opus 4.8

This is the closest price matchup in the flagship lineup, so the decision comes down to access and agentic tooling, not sticker price. GPT-5.6 Sol costs $5 input and $30 output per million tokens; Claude Opus 4.8 costs $5 input and $25 output. Opus 4.8 is slightly cheaper on output and, more importantly, generally available today. GPT-5.6 is still preview-only.

This page compares the two on the things a buyer controls: can you get it, what it costs, how it handles coding and agentic work, and whether it fits your compliance rules. We skip benchmark chasing. The goal is a clear, defensible pick for your workload.

GPT-5.6 Sol adds max and ultra reasoning modes, where ultra uses subagents for complex work. Claude Opus 4.8 is Anthropic's strong general-purpose coder and powers Claude Code. Both are capable; the deciding factors here are access and agentic ecosystem.

GPT-5.6 (Sol) vs. Claude Opus 4.8: Side-by-Side

Price: the closest matchup in the lineup

GPT-5.6 Sol and Claude Opus 4.8 are near price parity, with Opus slightly cheaper on output. Both cost $5 per million input tokens. Sol costs $30 per million output tokens, while Opus 4.8 costs $25.

That $5 output gap is small for most workloads. On output-heavy jobs like long drafting or code generation, it adds up, and Opus 4.8 wins on cost there. On input-heavy jobs like document review, the two are even.

Price should not decide the pick on its own while access is uneven. A near-tie on token cost has no value if you cannot license one of the models yet. Weigh price against availability and compliance together.

• GPT-5.6 Sol: $5 input / $30 output per million tokens.
• Claude Opus 4.8: $5 input / $25 output per million tokens.
• Same input price; Opus 4.8 is $5 cheaper per million output tokens.

→ Compare per-token pricing for every AI model

Availability: what can you deploy today?

Claude Opus 4.8 is the only one of these two you can deploy today without a waitlist. It is generally available in Claude Code and the API. GPT-5.6 is in a limited preview open only to a small set of vetted organizations, via API and Codex, at the US government's request.

For most teams, this ends the debate for near-term projects. You cannot build a launch plan around a model you cannot license. GPT-5.6 general availability is planned in the coming weeks, but no firm date is public.

Because the price is nearly tied, access is the real separator here. Opus 4.8 ships now; Sol may ship later. If your team is not in the preview, Opus 4.8 is the practical flagship choice today.

• Need to ship this quarter: Claude Opus 4.8 is deployable now.
• Not in the GPT-5.6 preview: you cannot use Sol yet.
• Planning ahead: track the GPT-5.6 GA date before committing.

Coding and agentic workflows

Both models are strong at coding and agentic work, so the split is about ecosystem and reasoning modes. Claude Opus 4.8 is a strong general-purpose coder and powers Claude Code, Anthropic's agentic coding tool. That tight integration is a real advantage for teams already building agent workflows.

GPT-5.6 Sol targets the hardest coding and security research. It adds max and ultra reasoning modes, where ultra uses subagents to speed up complex work. Those modes can help on deep, multi-step problems.

The practical difference is what you can wire up today. Opus 4.8 has a shipping agentic tool in Claude Code you can adopt now. Sol's reasoning modes are promising, but you need preview access to test them on your own tasks.

• Opus 4.8: strong coder, powers the shipping Claude Code agentic tool.
• GPT-5.6 Sol: max and ultra reasoning modes for hard coding and security work.
• Agentic ecosystem you can use today favors Opus 4.8.

Compliance: which fits regulated data?

Claude Opus 4.8 ships with a documented compliance stack and standard Claude guardrails. It inherits Anthropic SOC 2 and ISO 27001, with a HIPAA BAA on the API and Enterprise plans. It uses standard Claude safety guardrails rather than the Mythos-class retention rules that apply to Fable 5.

GPT-5.6 inherits OpenAI's platform coverage: SOC 2, ISO 27001, and a HIPAA BAA on the API and Enterprise, once a model is in scope. Because GPT-5.6 is still a preview, confirm the specific model is named in your BAA before sending regulated data.

The key compliance difference is confirmability. You can verify Opus 4.8 coverage and sign a BAA today. For GPT-5.6, you must wait for the model to be in scope and named in your agreement.

• Opus 4.8: SOC 2, ISO 27001, HIPAA BAA on API and Enterprise; standard guardrails.
• GPT-5.6: inherits OpenAI SOC 2, ISO 27001, HIPAA BAA once in scope.
• Confirm the exact model is named in your BAA before sending regulated data.

How to choose for your business

Choose based on access first, then agentic fit, then the small price gap. If you must ship soon, Claude Opus 4.8 is the deployable flagship today. If you are in the GPT-5.6 preview and want its max or ultra reasoning modes, Sol is worth evaluating.

Match the model to the workload, not the hype. Agentic coding and Claude Code adoption favor Opus 4.8 now. Deep multi-step reasoning may favor Sol's ultra mode, once you can access it.

Run a short pilot before you commit. Test agentic tool use, latency, and cost on your own tasks. A one-week trial reveals more than any benchmark table.

• Ship now with a shipping agentic tool: Claude Opus 4.8.
• Deep reasoning modes, if you have preview access: GPT-5.6 Sol.
• Output-heavy and cost-sensitive: Opus 4.8 is $5 cheaper per million output tokens.

The Verdict

Claude Opus 4.8 wins for most businesses today on availability. It is generally available in Claude Code and the API, while GPT-5.6 stays in a restricted preview at the US government's request. With price nearly tied, access is the deciding factor.

On price the two are close, with Opus 4.8 slightly cheaper. Both cost $5 per million input tokens; Opus 4.8 costs $25 output versus Sol's $30. Output-heavy workloads tilt toward Opus 4.8.

GPT-5.6 Sol earns a look for its max and ultra reasoning modes if your organization is in the preview. For agentic coding you can deploy now, Opus 4.8 and Claude Code are the safer bet.