Quick answer
- Claude Fable 5 price
- $10 in / $50 out per MTok
- GPT-5.6 Sol price
- $4 in / $20 out per MTok
- Fable 5 headline
- SWE-bench Verified 95.0% (swebench.com leaderboard)
- Sol headline
- Terminal-Bench 2.1 88.8%, 91.9% ultra (OpenAI launch materials)
Head-to-Head: The Verified Specs
Both models were new when this comparison was written. Claude Fable 5 shipped June 9, 2026, and redeployed globally on July 1. GPT-5.6 Sol went GA July 9, 2026. Here is everything we verified side by side, with the gaps in the public record marked as gaps rather than papered over:
| Claude Fable 5 | GPT-5.6 Sol | |
|---|---|---|
| Price (per MTok) | $10 in / $50 out | $4 in / $20 out |
| Released | June 9, 2026 | July 9, 2026 |
| Context window | 1M tokens (128k output) | Not in our verified data |
| Signature capability | Adaptive thinking, always on | Max reasoning effort + ultra mode (parallel subagents) |
| Access today | Claude Code /model claude-fable-5 (/model fable selects Fable 5.1 from v2.1.257) | Codex, still selectable during the GPT-6 rollout |
| Tier in vendor lineup | Frontier (Mythos-class, above Opus) | Frontier (only 5.6 tier with ultra mode) |
Deeper single-model breakdowns live on the dedicated pages: Claude Fable 5 for coding and GPT-5.6 Sol for coding.
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The Benchmark Problem: Two Vendors, Two Features
Here is the thing most head-to-head posts skip: Anthropic and OpenAI publish different benchmarks, so their launch numbers literally cannot be compared cell by cell. Anthropic's feature for Fable 5 is repo-level issue resolution: SWE-bench Verified 95.0% (swebench.com leaderboard) and SWE-bench Pro 80.3%. OpenAI's feature for Sol is terminal-agent competence: Terminal-Bench 2.1 88.8%, rising to 91.9% in ultra mode. Each vendor is showcasing the benchmark family it wins.
The cross-benchmark evidence is thin but not zero. Third-party SWE-bench Pro runs, not OpenAI-published, place Sol at 64.6% against Fable 5's 80.3%, a wide gap on the one shared yardstick we have. On the other side, OpenAI claims an ALE score of 53.6 and an Artificial Analysis Coding Agent Index of 80.0 for Sol; we have not verified either independently, so treat those as OpenAI's claims.
Community sentiment matched the split. The Hacker News discussion titled “Claude Fable 5 vs GPT-5.5: Better Planning, Similar Execution” captured it for the previous match-up, and the pattern held: Claude tended to win on planning and architecture, GPT on terminal execution speed.
Cost Math: What a Feature Actually Costs
Sol undercuts Fable 5 by 60% on both sides of the meter ($4 vs $10 per MTok input, $20 vs $50). On a realistic agentic feature, say 500k input tokens of repo context and spec, 100k output tokens of code and reasoning, the math looks like this:
| 500k in / 100k out | Claude Fable 5 | GPT-5.6 Sol |
|---|---|---|
| Input cost | $5.00 | $2.00 |
| Output cost | $5.00 | $2.00 |
| Feature total | $10.00 | $4.00 |
About $10.00 versus $4.00 per feature. Whether the premium is worth it depends entirely on the story: on a hard cross-cutting refactor, one failed run costs more than the price difference; on a mechanical terminal chain, it probably is not. For the broader Claude-side price ladder, see the best Claude model for coding.
When to Pick Which
This was the split while both models were current. Their successors need their own evidence: start with Claude Opus 5.5 vs GPT-6 Astra.
Pick Claude Fable 5 for
Pick GPT-5.6 Sol for
Or Run Both on One Board
The quiet answer to “Fable or Sol” in mid-2026 was: both. Dual-tool workflows are mainstream now, OpenAI even ships a Codex plugin for Claude Code, because the two vendors' strengths are complementary rather than overlapping.
That is the setup AIDEN is built for. It is a macOS desktop app that orchestrates your existing Claude Code and Codex CLIs on one kanban board: BYOK, local-first, every feature gated behind an approved spec. Assign a Claude model to the gnarly cross-cutting refactor and a GPT model to the migration feature, in the same project, each on its own git branch. The comparison with running Codex bare is covered in AIDEN vs Codex CLI, and the model hub with every current option lives at AI models for coding.