Models, measured side by side
Claude Opus 5.5 vs GPT-6 Astra
Compare Claude Opus 5.5, GPT-6 Astra by token pricing, context length, benchmark results, speed and tool support.
Monthly workload
Monthly cost breakdown
InputOutput
Claude Opus 5.5
$180 / mo
GPT-6 Astra
$450 / mo
Performance comparison
Claude Opus 5.5
57.6
GPT-6 Astra
52.7
Overview
Pricing & capacity
| Pricing & capacity | Claude Opus 5.5 | GPT-6 Astra |
|---|---|---|
| Input / 1M tokens | $4.00 | $10 |
| Output / 1M tokens | $20 | $50 |
| Cached input / 1M | $0.20 | $1.00 |
| Monthly cost | $180 | $450 |
| Context window | 1M | 1.1M |
| Maximum output | 128K | 128K |
Input / 1M tokens
- Claude Opus 5.5
- $4.00
- GPT-6 Astra
- $10
Output / 1M tokens
- Claude Opus 5.5
- $20
- GPT-6 Astra
- $50
Cached input / 1M
- Claude Opus 5.5
- $0.20
- GPT-6 Astra
- $1.00
Monthly cost
- Claude Opus 5.5
- $180
- GPT-6 Astra
- $450
Context window
- Claude Opus 5.5
- 1M
- GPT-6 Astra
- 1.1M
Maximum output
- Claude Opus 5.5
- 128K
- GPT-6 Astra
- 128K
Benchmarks & performance
| Benchmarks & performance | Claude Opus 5.5 | GPT-6 Astra |
|---|---|---|
| Arena Elo | Not listed | 1,288 |
| MMLU-Pro | Not listed | 88.3% |
| Intelligence Index | 57.6 | 52.7 |
| GPQA | Not listed | 96.1% |
| Humanity’s Last Exam | 61.4% | 54.7% |
| SciCode | 66.9% | 56.5% |
| Output speed | 91 tokens/s | 60 tokens/s |
| Time to first token | 755.54 s | 287.74 s |
| DesignArena rating | 1,407 | 1,384 |
| DesignArena win rate | 65.3% | 64.8% |
Arena Elo
- Claude Opus 5.5
- Not listed
- GPT-6 Astra
- 1,288
MMLU-Pro
- Claude Opus 5.5
- Not listed
- GPT-6 Astra
- 88.3%
Intelligence Index
- Claude Opus 5.5
- 57.6
- GPT-6 Astra
- 52.7
GPQA
- Claude Opus 5.5
- Not listed
- GPT-6 Astra
- 96.1%
Humanity’s Last Exam
- Claude Opus 5.5
- 61.4%
- GPT-6 Astra
- 54.7%
SciCode
- Claude Opus 5.5
- 66.9%
- GPT-6 Astra
- 56.5%
Output speed
- Claude Opus 5.5
- 91 tokens/s
- GPT-6 Astra
- 60 tokens/s
Time to first token
- Claude Opus 5.5
- 755.54 s
- GPT-6 Astra
- 287.74 s
DesignArena rating
- Claude Opus 5.5
- 1,407
- GPT-6 Astra
- 1,384
DesignArena win rate
- Claude Opus 5.5
- 65.3%
- GPT-6 Astra
- 64.8%
6 of 10
Tools & features
| Tools & features | Claude Opus 5.5 | GPT-6 Astra |
|---|---|---|
| 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 | Supported |
| Parallel tool calls | Not listed | Not listed |
| Prompt caching | Supported | Supported |
Function calling
- Claude Opus 5.5
- Supported
- GPT-6 Astra
- Supported
Structured outputs
- Claude Opus 5.5
- Supported
- GPT-6 Astra
- Supported
JSON mode
- Claude Opus 5.5
- Supported
- GPT-6 Astra
- Supported
Reasoning
- Claude Opus 5.5
- Supported
- GPT-6 Astra
- Supported
Built-in web search
- Claude Opus 5.5
- Not listed
- GPT-6 Astra
- Not listed
Log probabilities
- Claude Opus 5.5
- Not listed
- GPT-6 Astra
- Not listed
Deterministic seed
- Claude Opus 5.5
- Not listed
- GPT-6 Astra
- Supported
Parallel tool calls
- Claude Opus 5.5
- Not listed
- GPT-6 Astra
- Not listed
Prompt caching
- Claude Opus 5.5
- Supported
- GPT-6 Astra
- Supported
6 of 9
API & availability
| API & availability | Claude Opus 5.5 | GPT-6 Astra |
|---|---|---|
| API identifier | claude-opus-5.5 | gpt-6-astra |
| API providers | Not listed | OpenAI, Azure, OpenAI, Amazon Bedrock, Azure, OpenAI |
| Knowledge cutoff | Not listed | Not listed |
| Prices checked | Oct 8, 2026 | Oct 8, 2026 |
API identifier
- Claude Opus 5.5
claude-opus-5.5- GPT-6 Astra
gpt-6-astra
API providers
- Claude Opus 5.5
- Not listed
- GPT-6 Astra
- OpenAI, Azure, OpenAI, Amazon Bedrock, Azure, OpenAI
Knowledge cutoff
- Claude Opus 5.5
- Not listed
- GPT-6 Astra
- Not listed
Prices checked
- Claude Opus 5.5
- Oct 8, 2026
- GPT-6 Astra
- Oct 8, 2026
About the models
Claude 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 & detailsGPT-6 Astra
OpenAI's flagship GPT-6 model for the hardest reasoning, coding and agentic work. Long-context requests (above 272K input tokens) bill at $20 input / $75 output per 1M.
Full pricing & detailsComparison FAQ
Claude Opus 5.5: $4.00 input and $20 output per million tokens. GPT-6 Astra: $10 input and $50 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.