Claude Fable 5 vs GPT-5.6 Sol
Pricing, benchmarks, and use case comparison
Verdict
Our pick: Claude Fable 5The two most capable frontier models of mid-2026: pick Claude Fable 5 for the highest generally-available coding and reasoning ceiling, or GPT-5.6 Sol if you have preview access and want its top terminal-agent Ultra score.
Specs comparison
| Claude Fable 5 | GPT-5.6 Sol | |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Type | Closed source | Closed source |
| Context window | ✓1M | Not announced |
| Input / 1M tokens | $10.00 | ✓$5.00 |
| Output / 1M tokens | $50.00 | $30.00 |
| Release date | 2026-06 | 2026-06 |
Benchmarks
| Benchmark | Claude Fable 5 | GPT-5.6 Sol |
|---|---|---|
| SWE-bench Verified | 95.0% | - |
| Terminal-Bench 2.1 | 88.0% | ✓88.8% |
| GPQA Diamond | 92.6% | - |
| SWE-bench Pro | 80.3% | - |
| 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
Both sit at the very top. Claude Fable 5 shows state-of-the-art results on nearly all tested benchmarks: reportedly ~95.0% SWE-bench Verified, 88.0% Terminal-Bench 2.1, 80.3% SWE-bench Pro, and 92.6% GPQA Diamond (coding 99, reasoning 98). GPT-5.6 Sol reports 88.8% Terminal-Bench 2.1, climbing to 91.9% in Ultra mode (subagent orchestration), with coding 97 and reasoning 97. Fable 5 leads on SWE-bench and general capability; Sol's Ultra mode takes the single highest terminal-agent figure between them.
Availability, price, and context
Fable 5 is generally available across the Claude API and major clouds with a documented 1M context, priced at $10/$50 per 1M (it also routes a small share of sensitive queries to Opus 4.8). GPT-5.6 Sol is a gated, government-coordinated limited preview with an unstated context window and an inferred model id, priced at $5/$30. So Sol is cheaper per token but hard to access; Fable 5 is deployable today at a premium.
Which to pick
- Pick Claude Fable 5 for long-horizon autonomous agents and frontier engineering you can deploy now, where its lead widens on longer, harder tasks and maximum accuracy outweighs cost.
- Pick GPT-5.6 Sol if you are an approved preview partner wanting the top terminal-agent Ultra score and lower per-token pricing, and can accept gated access and an unconfirmed context window.
Which should you choose?
Choose Claude Fable 5 if...
- →You need the absolute highest capability Anthropic offers for hard tasks
- →You run long, complex autonomous agents where quality compounds over many steps
- →You do frontier-level engineering, research, or analytics and cost is secondary
- →You want maximum accuracy on the toughest coding and reasoning benchmarks
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