Claude Opus 4.8 vs GPT-5.6 Sol
Pricing, benchmarks, and use case comparison
Verdict
Our pick: Claude Opus 4.8Pick Claude Opus 4.8 for the strongest generally-available frontier model you can deploy today; pick GPT-5.6 Sol only if you have preview access and want the highest terminal-agent ceiling via its max and ultra modes.
Specs comparison
| Claude Opus 4.8 | GPT-5.6 Sol | |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Type | Closed source | Closed source |
| Context window | ✓1M | Not announced |
| Input / 1M tokens | $5.00 | $5.00 |
| Output / 1M tokens | $25.00 | $30.00 |
| Release date | 2026-05 | 2026-06 |
Benchmarks
| Benchmark | Claude Opus 4.8 | GPT-5.6 Sol |
|---|---|---|
| SWE-bench Verified | 88.6% | - |
| SWE-bench Pro | 69.2% | - |
| Terminal-Bench 2.1 | 74.6% | ✓88.8% |
| GPQA Diamond | 93.6% | - |
| Artificial Analysis Intelligence Index | 61.4 | - |
| Terminal-Bench 2.1 (Ultra) | - | 91.9% |
| ExploitBench | - | competitive with Mythos Preview |
Scores sourced from official provider release posts and independent benchmark aggregators.
Capability and benchmarks
On paper GPT-5.6 Sol has the higher ceiling: 88.8% Terminal-Bench 2.1, rising to 91.9% in Ultra mode (subagent orchestration), with capability scores of coding 97 and reasoning 97. Claude Opus 4.8 answers with 88.6% SWE-bench Verified, 69.2% SWE-bench Pro, 74.6% Terminal-Bench 2.1, and 93.6% GPQA Diamond (coding 96, reasoning 95). Sol edges the terminal-agent and raw-intelligence numbers; Opus is right behind and stronger on the science benchmark shown here.
Availability, price, and context
The decisive gap is access. Opus 4.8 is generally available across the Claude API, Bedrock, Vertex AI, and Microsoft Foundry with a documented 1M context and $5/$25 pricing. GPT-5.6 Sol is a gated, U.S.-government-coordinated limited preview: its context window is not stated, its API id is an inferred placeholder, and access needs case-by-case approval. Preview pricing matches GPT-5.5 at $5/$30, so Sol's output is also pricier than Opus's $25.
Which to pick
- Pick Opus 4.8 for essentially every production scenario today: it is deployable, documented, cheaper on output, and near the top of the leaderboard.
- Pick GPT-5.6 Sol only if you are an approved preview partner chasing the absolute highest terminal-agent score and want the max reasoning-effort and ultra subagent modes, accepting an unconfirmed context window and gated access.
Which should you choose?
Choose Claude Opus 4.8 if...
- →You need top-tier autonomous coding and multi-step agentic reliability
- →You run long-horizon agent traces that previously derailed after compaction
- →You want enterprise-grade reasoning with 1M context and 128k output
- →You need throughput and are willing to pay fast-mode premium for 2.5x speed
Choose GPT-5.6 Sol if...
- →You are an approved preview partner needing the most capable model for agentic software engineering
- →Complex multi-step tasks that benefit from subagent orchestration (Ultra) or maximum reasoning depth (max)
- →Frontier scientific research, professional knowledge work, or security-sensitive workloads