Models, measured side by side
Claude Fable 5.1 vs Claude Opus 5.5
Compare Claude Fable 5.1, Claude Opus 5.5 by token pricing, context length, benchmark results, speed and tool support.
Monthly workload
Monthly cost breakdown
InputOutput
Claude Fable 5.1
$450 / mo
Claude Opus 5.5
$180 / mo
Performance comparison
Claude Fable 5.1
53.4
Claude Opus 5.5
57.6
Overview
Pricing & capacity
| Pricing & capacity | Claude Fable 5.1 | Claude Opus 5.5 |
|---|---|---|
| Input / 1M tokens | $10 | $4.00 |
| Output / 1M tokens | $50 | $20 |
| Cached input / 1M | $0.25 | $0.20 |
| Monthly cost | $450 | $180 |
| Context window | 1M | 1M |
| Maximum output | 128K | 128K |
Input / 1M tokens
- Claude Fable 5.1
- $10
- Claude Opus 5.5
- $4.00
Output / 1M tokens
- Claude Fable 5.1
- $50
- Claude Opus 5.5
- $20
Cached input / 1M
- Claude Fable 5.1
- $0.25
- Claude Opus 5.5
- $0.20
Monthly cost
- Claude Fable 5.1
- $450
- Claude Opus 5.5
- $180
Context window
- Claude Fable 5.1
- 1M
- Claude Opus 5.5
- 1M
Maximum output
- Claude Fable 5.1
- 128K
- Claude Opus 5.5
- 128K
Benchmarks & performance
| Benchmarks & performance | Claude Fable 5.1 | Claude Opus 5.5 |
|---|---|---|
| Arena Elo | Not listed | Not listed |
| MMLU-Pro | Not listed | Not listed |
| Intelligence Index | 53.4 | 57.6 |
| GPQA | 93.7% | Not listed |
| Humanity’s Last Exam | 59.1% | 61.4% |
| SciCode | 63.1% | 66.9% |
| Output speed | 61 tokens/s | 91 tokens/s |
| Time to first token | 259.12 s | 755.54 s |
| DesignArena rating | 1,340 | 1,407 |
| DesignArena win rate | 59.3% | 65.3% |
Arena Elo
- Claude Fable 5.1
- Not listed
- Claude Opus 5.5
- Not listed
MMLU-Pro
- Claude Fable 5.1
- Not listed
- Claude Opus 5.5
- Not listed
Intelligence Index
- Claude Fable 5.1
- 53.4
- Claude Opus 5.5
- 57.6
GPQA
- Claude Fable 5.1
- 93.7%
- Claude Opus 5.5
- Not listed
Humanity’s Last Exam
- Claude Fable 5.1
- 59.1%
- Claude Opus 5.5
- 61.4%
SciCode
- Claude Fable 5.1
- 63.1%
- Claude Opus 5.5
- 66.9%
Output speed
- Claude Fable 5.1
- 61 tokens/s
- Claude Opus 5.5
- 91 tokens/s
Time to first token
- Claude Fable 5.1
- 259.12 s
- Claude Opus 5.5
- 755.54 s
DesignArena rating
- Claude Fable 5.1
- 1,340
- Claude Opus 5.5
- 1,407
DesignArena win rate
- Claude Fable 5.1
- 59.3%
- Claude Opus 5.5
- 65.3%
Tools & features
| Tools & features | Claude Fable 5.1 | Claude Opus 5.5 |
|---|---|---|
| Function calling | Supported | Supported |
| Structured outputs | Supported | Supported |
| JSON mode | Supported | Supported |
| Reasoning | Supported | Supported |
| Built-in web search | Not listed | Not listed |
| Log probabilities | Not listed | Not listed |
| Deterministic seed | Not listed | Not listed |
| Parallel tool calls | Not listed | Not listed |
| Prompt caching | Supported | Supported |
Function calling
- Claude Fable 5.1
- Supported
- Claude Opus 5.5
- Supported
Structured outputs
- Claude Fable 5.1
- Supported
- Claude Opus 5.5
- Supported
JSON mode
- Claude Fable 5.1
- Supported
- Claude Opus 5.5
- Supported
Reasoning
- Claude Fable 5.1
- Supported
- Claude Opus 5.5
- Supported
Built-in web search
- Claude Fable 5.1
- Not listed
- Claude Opus 5.5
- Not listed
Log probabilities
- Claude Fable 5.1
- Not listed
- Claude Opus 5.5
- Not listed
Deterministic seed
- Claude Fable 5.1
- Not listed
- Claude Opus 5.5
- Not listed
Parallel tool calls
- Claude Fable 5.1
- Not listed
- Claude Opus 5.5
- Not listed
Prompt caching
- Claude Fable 5.1
- Supported
- Claude Opus 5.5
- Supported
API & availability
| API & availability | Claude Fable 5.1 | Claude Opus 5.5 |
|---|---|---|
| API identifier | claude-fable-5.1 | claude-opus-5.5 |
| API providers | Not listed | Not listed |
| Knowledge cutoff | Not listed | Not listed |
| Prices checked | Oct 8, 2026 | Oct 8, 2026 |
API identifier
- Claude Fable 5.1
claude-fable-5.1- Claude Opus 5.5
claude-opus-5.5
API providers
- Claude Fable 5.1
- Not listed
- Claude Opus 5.5
- Not listed
Knowledge cutoff
- Claude Fable 5.1
- Not listed
- Claude Opus 5.5
- Not listed
Prices checked
- Claude Fable 5.1
- Oct 8, 2026
- Claude Opus 5.5
- Oct 8, 2026
About the models
Claude Fable 5.1
Claude Fable 5.1 improves on Claude Fable 5 across the board, with the biggest gains in agentic coding, long-running agentic workflows, and knowledge work: long code refactors, front-end and visual...
Full pricing & detailsClaude Opus 5.5
Claude Opus 5.5 is Anthropic's flagship model for demanding reasoning, coding, and long-horizon agentic work, succeeding Claude Opus 5. It is particularly strong at multi-step changes in large codebases, code...
Full pricing & detailsComparison FAQ
Claude Fable 5.1: $10 input and $50 output per million tokens. Claude Opus 5.5: $4.00 input and $20 output per million tokens. The cheaper choice depends on your input-to-output ratio; a model can have a lower input rate but a higher output rate.