Anthropic Claude Fable 5 (1M) vs GPT-5.4
Side-by-side comparison of pricing, context window, capabilities, and a real-cost sample workload.
Option A
Anthropic Claude Fable 5 (1M)
by Anthropic
Context: 1M
Input: $10.00 / 1M
Output: $50.00 / 1M
Released: 2026-06
Detailed Comparison
| Dimension | Anthropic Claude Fable 5 (1M) | GPT-5.4 |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Context window Winner | 1M | 256K |
| Input price ($/1M) Winner | $10.00 | $25.00 |
| Output price ($/1M) Winner | $50.00 | $100.00 |
| Sample workload cost Winner 1M input + 500K output tokens
|
$35.00 | $75.00 |
| Released Winner | 2026-06 | 2026-03 |
| Tokenizer | claude-4 | cl100k_base |
The verdict
On the dimensions we measured, Anthropic Claude Fable 5 (1M) wins more often - particularly on cost-effectiveness for a typical 1M+0.5M workload.
Anthropic Claude Fable 5 (1M) - Key features
The first public Mythos-class model - Anthropic's most powerful generally available model, sharing Mythos 5's underlying intelligence with added safeguards that fall back to Opus 4.8 on sensitive prompts.
- Mythos-class intelligence for everyone
- Adaptive thinking (no fixed budget)
- 1M token context window
- Top-tier coding & agentic work
- Built-in safety classifiers
GPT-5.4 - Key features
OpenAI's most advanced model with enhanced reasoning, longer context, and multimodal capabilities. Top of the line for complex tasks.
- 256K context window
- Advanced reasoning
- Multimodal (vision+audio)
- Improved instruction following
- Function calling v3
How to choose
- Pick the cheaper model if your workload is mostly straightforward classification, extraction, or summarization.
- Pick the bigger context if you process long documents, large codebases, or multi-document research.
- Pick the more recent release if you need state-of-the-art reasoning quality and don't mind paying a bit more.
- Use both via a routing layer - send simple tasks to the cheaper one and complex tasks to the smarter one. This is the highest-ROI optimization in production AI.
Estimate the real cost of either model for your prompts using our Token Calculator.