Claude Fable 5 vs GPT-5.1
Benchmarks, API pricing and specs, head to head. Data updated 2026-06-10.
Claude Fable 5
Anthropic · Jun 2026
The first GA model of Anthropic's Mythos class — a tier above Opus — and the current SWE-bench Verified leader, at $10/$50 per 1M tokens.
GPT-5.1
59.6OpenAI · Nov 2025
A November 2025 update to GPT-5 with adaptive reasoning that spends thinking tokens only when a task needs them.
The verdict
Claude Fable 5 wins 1 of the 1 benchmarks these models share, against 0 for GPT-5.1. On price the gap is dramatic: GPT-5.1 works out roughly 5.8x cheaper per blended million tokens. Claude Fable 5 also takes 1M of context versus 400K for GPT-5.1.
Benchmark head-to-head 1–0
Specs & pricing
| Claude Fable 5 | GPT-5.1 | |
|---|---|---|
| modhub Index | — | 59.6 |
| Input price / 1M | $10 | $1.25 |
| Output price / 1M | $50 | $10 |
| Context window | 1M | 400K |
| Max output | 128K | 128K |
| Open weights | no | no |
| Reasoning model | yes | yes |
| Multimodal input | text, image | text, image |
| Knowledge cutoff | Jan 2026 | Sep 2024 |
| Released | Jun 2026 | Nov 2025 |
| Example monthly cost* | $175.00 | $27.50 |
* 10M input + 1.5M output tokens per month at list prices, no caching. Green = better value on that row.
Frequently asked questions
- Which is better, Claude Fable 5 or GPT-5.1?
- Claude Fable 5 wins 1 of the 1 benchmarks these models share, against 0 for GPT-5.1. On price the gap is dramatic: GPT-5.1 works out roughly 5.8x cheaper per blended million tokens. Claude Fable 5 also takes 1M of context versus 400K for GPT-5.1.
- Which is cheaper, Claude Fable 5 or GPT-5.1?
- Claude Fable 5 costs $10/$50 per million input/output tokens, while GPT-5.1 costs $1.25/$10. For a typical workload of 10M input and 1.5M output tokens per month, that's $175.00 versus $27.50.
- Which model is better for coding, Claude Fable 5 or GPT-5.1?
- On SWE-bench Verified — the standard agentic-coding benchmark — Claude Fable 5 scores ~95% versus 76.3% for GPT-5.1, making Claude Fable 5 the stronger pick for coding agents.