Claude Opus 4.8 vs GPT-5.6 Sol
GPT-5.6 Sol and Claude Opus 4.8 are the comparison many teams run when deciding whether to stay on an existing Opus 4.8 deployment or move to OpenAI's July 2026 GA frontier route. OpenAI's GPT-5.6 launch materials compare Sol against Opus 4.8 on agent, cyber, and knowledge-work rows. Opus 4.8 remains a relevant Claude high-end baseline, but Claude Fable 5 is now Anthropic's newer top-tier anchor.
Pick GPT-5.6 Sol for new frontier OpenAI work after the July 2026 GA launch, especially when OpenAI launch-table rows on OSWorld 2.0, BrowseComp, GPQA Diamond, and cyber tasks matter in procurement. Keep Claude Opus 4.8 when you need established Claude behavior, fallback predictability, or a prior-deployment baseline while evaluating Fable 5. Do not treat Opus 4.8 as Anthropic's newest top model after Fable 5 access was restored.
Decision scorecard
Local evidence first| Signal | Claude Opus 4.8 | GPT-5.6 Sol |
|---|---|---|
| Best for | reasoning-heavy apps, multimodal apps, and tool-calling agents | reasoning-heavy apps, multimodal apps, and tool-calling agents |
| Decision fit | Coding, RAG, and Agents | Coding, RAG, and Agents |
| Context window | 1m | 1.05m |
| Cheapest output | $25/1M tokens | $30/1M tokens |
| Provider routes | 6 tracked | 2 tracked |
| Shared benchmarks | SWE-bench Pro leader | 5 shared |
Decision tradeoffs
- Claude Opus 4.8 holds a shared-benchmark lead on SWE-bench Pro, ahead by 4.6 points.
- Claude Opus 4.8 has the lower cheapest tracked output price at $25/1M tokens.
- Claude Opus 4.8 has broader tracked provider coverage for fallback and procurement flexibility.
- Claude Opus 4.8 uniquely exposes Structured outputs, Computer use, and Parallel agents in local model data.
- Local decision data tags Claude Opus 4.8 for Coding, RAG, and Agents.
- GPT-5.6 Sol holds a shared-benchmark lead on Google-Proof Q&A, ahead by 1 points.
- GPT-5.6 Sol has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Local decision data tags GPT-5.6 Sol for Coding, RAG, and Agents.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output route or tier on this page.
Claude Opus 4.8
$10,250
Cheapest tracked route/tier: Anthropic
GPT-5.6 Sol
$11,500
Cheapest tracked route/tier: OpenAI API 0-272K input tokens
Estimated monthly gap: $1,250. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on OpenRouter; start route-level A/B tests there.
- GPT-5.6 Sol is $5/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- Check replacement coverage for Structured outputs, Computer use, and Parallel agents before moving production traffic.
- Provider overlap exists on OpenRouter; start route-level A/B tests there.
- Claude Opus 4.8 is $5/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Claude Opus 4.8 adds Structured outputs, Computer use, and Parallel agents in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-05-28 | 2026-07-09 |
| Context window | 1m | 1.05m |
| Parameters | — | — |
| Architecture | Decoder Only | Decoder Only |
| License | Proprietary | Proprietary |
| Openness | Proprietary | Proprietary |
| Weights | Not released | Not released |
| Code | Not released | Unknown |
| Commercial use | Commercial use: conditional | Commercial use: conditional |
| Knowledge cutoff | 2026-01 | - |
Pricing and availability
| Pricing attribute | Claude Opus 4.8 | GPT-5.6 Sol |
|---|---|---|
| Input price | $5/1M tokens |
|
| Output price | $25/1M tokens |
|
| Providers |
Capabilities
| Capability | Claude Opus 4.8 | GPT-5.6 Sol |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | Yes | Yes |
| Function calling | Yes | Yes |
| Tool use | Yes | Yes |
| Structured outputs | Yes | No |
| Code execution | Yes | Yes |
| IDE integration | No | No |
| Computer use | Yes | No |
| Parallel agents | Yes | No |
Benchmarks
| Benchmark | Claude Opus 4.8 | GPT-5.6 Sol |
|---|---|---|
| SWE-bench Pro | 69.2 | 64.6 |
| Google-Proof Q&A | 93.6 | 94.6 |
| Terminal-Bench 2.1 | 74.6 | 88.8 |
| GeneBench-Pro | 16.0 | 31.5 |
| BrowseComp — Multi-Agent | 88.5 | 92.2 |
Deep dive
OpenAI positions this as a launch-era comparison. Use GPT-5.6 Sol GA rows from OpenAI launch and API docs, and keep Opus 4.8 rows separate from Claude Fable 5 evidence.
Migration framing should be route-level testing, not a blanket replacement claim. Opus 4.8 may still fit regulated workflows or integrations that depend on its prior behavior profile, while Sol is the forward OpenAI path across ChatGPT, Codex, and the API.
Price and context should be compared with real prompt lengths. GPT-5.6 Sol lists $5/$30 up to 272K input tokens and $10/$45 above that threshold with a 1.05M context window. Opus 4.8 uses Anthropic's prior Opus pricing pattern in the seed and should be checked against current Anthropic docs before procurement.
For Anthropic teams evaluating upgrades inside Claude, route onward to Claude Fable 5 versus Opus 4.8 rather than assuming Opus 4.8 remains the top Anthropic tier.
FAQ
Is Claude Opus 4.8 still worth using?
Yes for teams that depend on Opus 4.8's established behavior profile or need a Claude fallback baseline. For new Anthropic top-tier work, evaluate Claude Fable 5 after verifying live access rather than treating Opus 4.8 as the newest flagship.
How does GPT-5.6 Sol compare on agent benchmarks?
OpenAI's July 2026 launch materials include Opus 4.8 comparison rows for agentic and knowledge-work tasks. Use those source-labeled OpenAI rows for Sol and Opus-specific Anthropic or independent rows for Opus 4.8 without mixing in Fable 5 data.
Should Opus 4.8 users move to Fable 5 instead?
For Anthropic-only upgrades, Fable 5 is the newer top-tier route once live access is verified. GPT-5.6 Sol is the relevant comparison when the decision is OpenAI versus an existing Opus 4.8 deployment.
Which model is cheaper?
Compare current OpenAI and Anthropic pricing for your prompt length. GPT-5.6 Sol uses OpenAI's tiered short- and long-context API rows. Opus 4.8 pricing should be checked on Anthropic's current docs and your cloud partner route.
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Last reviewed: 2026-07-09. Data sourced from public model cards and provider documentation.