Claude 4 Sonnet vs Claude Fable 5
Head-to-head specifications
| Metric | Claude 4 Sonnet | Claude Fable 5 | Difference |
|---|---|---|---|
| Intelligence Index | 29.0 | 60.0 | -51.7% |
| Coding Index | 37.6 | 76.5 | -50.8% |
| Agentic Index | 16.6 | 52.8 | — |
| Context window | 1M tokens | 1M tokens | — |
| Blended price ($/1M tokens) | $1.20 | $1.68 | -28.6% |
| Access | Proprietary API | Proprietary API | — |
- Claude Fable 5 leads overall capability (Intelligence Index 60.0 vs 29.0).
- Claude 4 Sonnet is the cheaper model to run at $1.20/1M blended tokens — about 1.4× cheaper.
Verdict: Claude 4 Sonnet or Claude Fable 5?
Claude 4 Sonnet advantages
- Affordability (+29%)
Claude Fable 5 advantages
- General intelligence (+52%)
- Coding ability (+51%)
- Agentic task performance (+69%)
Which should you choose?
- Choose the Claude 4 Sonnet if you want the lowest cost per token at scale.
- Choose the Claude Fable 5 if you need the strongest overall reasoning and accuracy.
Value for money
Claude Fable 5 offers more intelligence per dollar (1.5× the Intelligence-Index-per-cost of the alternative), making it the stronger value for high-volume use.
Claude 4 Sonnet vs Claude Fable 5: which should you choose?
Claude 4 Sonnet — Anthropic multimodal model with an Intelligence Index of 29, a 1M-token context window and a blended price of $1.2/1M tokens.
Claude Fable 5 — Anthropic multimodal model with an Intelligence Index of 60, a 1M-token context window and a blended price of $1.68/1M tokens.
Claude 4 Sonnet vs Claude Fable 5: Claude Fable 5 scores higher on the Intelligence Index. Claude Fable 5 leads overall capability (Intelligence Index 60.0 vs 29.0). Claude 4 Sonnet is the cheaper model to run at $1.20/1M blended tokens — about 1.4× cheaper.
Capability: intelligence, coding and agentic work
On the composite Intelligence Index the Claude Fable 5 scores 60.0 versus 29.0. For software development, the Coding Index puts Claude Fable 5 ahead (76.5 vs 37.6). On agentic, multi-step tool-use tasks, Claude Fable 5 measures stronger. Composite indices summarize many evaluations, but always test on your own workload before committing.
Context window and speed
The Claude 4 Sonnet accepts up to 1 million tokens per request, which sets how much documentation, transcript or code it can reason over at once.
Pricing and access
At blended per-token rates, Claude 4 Sonnet is the cheaper model to run ($1.20 vs $1.68 per 1M tokens). Claude 4 Sonnet is proprietary api and Claude Fable 5 is proprietary api. Open-weight models can be self-hosted, trading per-call cost for infrastructure you manage; for production also weigh rate limits, throughput and data-residency requirements.
The verdict
Both are credible choices in the ai model comparison space; the specification table above lays out every metric so you can weigh the trade-offs that matter to you. Pick the one whose strengths line up with how you will actually use it.
Frequently asked questions
Is the Claude 4 Sonnet better than the Claude Fable 5?
Claude Fable 5 takes the overall edge, though Claude 4 Sonnet wins in specific areas worth weighing. Claude Fable 5 leads overall capability (Intelligence Index 60.0 vs 29.0).
What is the main difference between the Claude 4 Sonnet and the Claude Fable 5?
Claude Fable 5 leads overall capability (Intelligence Index 60.0 vs 29.0). Claude 4 Sonnet is the cheaper model to run at $1.20/1M blended tokens — about 1.4× cheaper.
Which is better value?
Claude Fable 5 offers more intelligence per dollar (1.5× the Intelligence-Index-per-cost of the alternative), making it the stronger value for high-volume use.
Which should I choose?
Choose the Claude 4 Sonnet if you want the lowest cost per token at scale. Choose the Claude Fable 5 if you need the strongest overall reasoning and accuracy.
Methodology
Large language models are compared on independent leaderboard metrics: an Intelligence Index (a composite of reasoning and knowledge evaluations), Coding and Agentic indices where measured, community arena Elo, maximum context window, a blended API price per million tokens (weighted across cache-hit, input and output rates), and measured output speed in tokens per second. Where a model ships multiple reasoning-effort variants, we report its strongest variant. Benchmarks capture only part of real-world quality, which also depends on tool use, latency, safety and task fit — and this space moves quickly, so figures reflect the leaderboard snapshot on the page date.