When OpenAI launched GPT-5.6, the headline was that its flagship, Sol, was priced against Anthropic's second tier rather than its top one. With Claude Opus 5 now sitting at $5/$25, that comparison has become the most relevant flagship-to-flagship matchup for most API buyers — and on output tokens, Opus 5 is actually the cheaper of the two.
Claude Opus 5 vs GPT-5.6 Sol at a glance
| Claude Opus 5 | GPT-5.6 Sol | |
|---|---|---|
| Price (per 1M tokens) | $5 in / $25 out | $5 in / $30 out |
| Context window | 1M tokens | 1.5M tokens |
| Max output | 128K tokens | Not published |
| Cheaper siblings | Sonnet 5 $3/$15 · Haiku 4.5 $1/$5 | Terra $2.50/$15 · Luna $1/$6 |
| Premium sibling | Fable 5 $10/$50 | Sol Ultra (parallel sub-agent mode) |
| Multi-cloud | Bedrock, Vertex AI, Foundry | Azure-centric |
GPT-5.6 figures are from our GPT-5.6 vs Claude Fable 5 breakdown, current as of July 2026. We have not seen a published head-to-head benchmark between Claude Opus 5 and GPT-5.6 Sol, so treat any single-number claim about which is "better" with scepticism.
Choose Claude Opus 5 if
- Output-heavy workloads — $25 against $30 per million output tokens compounds fast on generation-heavy tasks.
- Deployment inside AWS or Google Cloud, where Claude runs natively on Bedrock and Vertex AI.
- Long agentic runs, self-verification, and multi-file software work.
Choose GPT-5.6 Sol if
- Single-shot ingestion beyond 1M tokens — Sol's 1.5M window is a real 50% edge.
- Existing OpenAI tooling, Codex workflows, and Azure-first infrastructure.
- Workloads already benchmarked on the GPT family where switching costs exceed the gain.
The verdict
Closer than the marketing on either side suggests. Run a twenty-task private evaluation on your own workload before committing — published benchmarks between these two are not directly comparable.
Whichever way you lean, run the decision on your own workload rather than a benchmark table. Twenty representative tasks from your real queue will tell you more than any published score.
More on Claude Opus 5
Start with the complete Claude Opus 5 guide for the overview, or go deeper:
Ready to go deeper?
Read the full Claude Opus 5 guideFrequently Asked Questions
Which is cheaper, Claude Opus 5 or GPT-5.6 Sol?
They match on input at $5 per million tokens, and Opus 5 is cheaper on output — $25 against Sol's $30. For generation-heavy workloads that 20% output difference is the number that matters; for ingestion-heavy workloads they are effectively level.
Which has the bigger context window?
GPT-5.6 Sol, at 1.5M tokens against Claude Opus 5's 1M — a genuine 50% advantage for single-shot ingestion of very large corpora. Opus 5 counters with a published 128K maximum output, where Sol's ceiling has not been published.
Which is better for coding?
There is no published head-to-head benchmark between these two specific models, so the honest answer is: test on your own repository. Broadly, the Claude line's strength is end-to-end work in unfamiliar codebases and long autonomous runs, while the GPT-5.6 family emphasises parallel breadth and raw speed.
