AI model comparison
Claude Sonnet 5.5 vs GPT-6 Astra
Pricing, context window, benchmarks, and features compared side by side. Or skip the guesswork and send one prompt to both.
Anthropic
Claude Sonnet 5.5
Claude Sonnet 5.5 is Anthropic's Sonnet-class model for well-scoped everyday work, succeeding Claude Sonnet 5 as a direct upgrade.
- Input / 1M
- $2
- Output / 1M
- $10
- Context
- 1M
OpenAI
GPT-6 Astra
GPT-6 Astra is OpenAI's flagship model for demanding end-to-end work.
- Input / 1M
- $10
- Output / 1M
- $50
- Context
- 1.05M
At a glance
Quick verdict
How the two models stack up on the things people ask about most.
Lower price
Claude Sonnet 5.5
5.0x cheaper for a typical chat
Higher intelligence score
Claude Sonnet 5.5
56 vs 52.7 on Artificial Analysis
Larger context window
GPT-6 Astra
1.05M vs 1M tokens
Newer release
Claude Sonnet 5.5
Released September 28, 2026
Benchmarks
Benchmark scores
Independent scores from Artificial Analysis. Higher is better.
Intelligence index
Claude Sonnet 5.556GPT-6 Astra52.7Coding index
Claude Sonnet 5.5Not availableGPT-6 Astra76.9Agentic index
Claude Sonnet 5.5Not availableGPT-6 Astra51Pricing
Claude Sonnet 5.5 vs GPT-6 Astra API pricing
Per-token API rates. Cheaper option highlighted.
| Metric | Claude Sonnet 5.5 | GPT-6 Astra |
|---|---|---|
| Input tokensPer 1M tokens | $2 | $10 |
| Output tokensPer 1M tokens | $10 | $50 |
| Cached input (read)Per 1M tokens | $0.10 | $1 |
| Cache writePer 1M tokens | $2.50 | $12.50 |
| Long-context pricingPer 1M tokens, for very long prompts | Same rate at any length | $20 in / $75 out above 272K |
| Web searchPer request | $0.01 | $0.01 |
What it costs in practice
Estimated cost per 1,000 requests at standard rates. Coding and long-document figures also show the cost when the input is already cached.
Chat message
2K in, 500 out
Claude Sonnet 5.5$9GPT-6 Astra$45Coding task
30K in, 4K out
Claude Sonnet 5.5$100$43 cachedGPT-6 Astra$500$230 cachedLong document summary
150K in, 2K out
Claude Sonnet 5.5$320$35 cachedGPT-6 Astra$1600$250 cachedSpecs
Context window and capabilities
How much each model can read, how much it can write, and what it accepts as input.
| Metric | Claude Sonnet 5.5 | GPT-6 Astra |
|---|---|---|
| Context window | 1M tokens | 1.05M tokens |
| Max output | 128K tokens | 128K tokens |
| Input types | File, Image, Text | File, Image, Text |
| Output types | Text | Text |
| Reasoning effort levels | Max, Extra high, High, Medium, Low | Max, Extra high, High, Medium, Low |
| Default reasoning effort | High | Medium |
| Release date | September 28, 2026 | September 4, 2026 |
Features
Supported features
API features available for each model.
| Metric | Claude Sonnet 5.5 | GPT-6 Astra |
|---|---|---|
| Tool calling | Supported | Supported |
| Structured outputs | Supported | Supported |
| JSON mode | Supported | Supported |
| Reasoning | Supported | Supported |
| Temperature | Not supported | Not supported |
| Stop sequences | Supported | Not supported |
| Deterministic seed | Not supported | Supported |
| Verbosity control | Supported | Supported |
Keep exploring
More on these models
Other head-to-heads, the full model page, and the alternatives list for each model.
Claude Sonnet 5.5View full model details- Claude Sonnet 5.5 vs Claude Opus 5.5
- Claude Sonnet 5.5 vs Claude Fable 5.1
- Claude Sonnet 5.5 vs GPT-6.1 Sol
- Claude Sonnet 5.5 vs Claude Opus 5
- Claude Sonnet 5.5 vs Claude Fable 5
- Claude Sonnet 5.5 vs Muse Spark 1.3
- Claude Sonnet 5.5 vs GPT-6 Sol
- Claude Sonnet 5.5 vs GPT-5.6 Sol
- Claude Sonnet 5.5 vs Grok 4.7
- Claude Sonnet 5.5 vs GLM 5.3
- Claude Sonnet 5.5 vs DeepSeek V4.1 Flash
- Claude Sonnet 5.5 vs GLM 5.3 Flash
- Claude Sonnet 5.5 vs MiMo-V2.6-Flash
- Claude Sonnet 5.5 vs Hy4 preview
- Claude Sonnet 5.5 vs GPT-6 Luna
- Claude Sonnet 5.5 vs DeepSeek V4 Flash 0731
GPT-6 AstraView full model details- GPT-6 Astra vs Claude Opus 5.5
- GPT-6 Astra vs Claude Fable 5.1
- GPT-6 Astra vs GPT-6.1 Sol
- GPT-6 Astra vs Claude Opus 5
- GPT-6 Astra vs Claude Fable 5
- GPT-6 Astra vs Muse Spark 1.3
- GPT-6 Astra vs GPT-6 Sol
- GPT-6 Astra vs GPT-5.6 Sol
- GPT-6 Astra vs Grok 4.7
- GPT-6 Astra vs GLM 5.3
- GPT-6 Astra vs Kimi K3
- GPT-6 Astra vs GLM 5.3 Flash
- GPT-6 Astra vs Gemini 3.8 Flash
- GPT-6 Astra vs DeepSeek V4.1 Flash
- GPT-6 Astra vs MiMo-V2.6-Flash
- GPT-6 Astra vs Hy4 preview
- GPT-6 Astra vs GPT-6 Luna
- GPT-6 Astra vs DeepSeek V4 Flash 0731
- GPT-6 Astra vs Gemini 3.1 Pro Preview
Our take
Claude Sonnet 5.5 is 5.0x cheaper for a typical chat. Claude Sonnet 5.5 scores higher on the Artificial Analysis Intelligence Index (56 vs 52.7). GPT-6 Astra has the larger context window (1.05M vs 1M tokens). The right pick depends on your workload, so the quickest way to settle it is to send the same prompt to both and compare.
FAQ
Frequently asked questions
Is Claude Sonnet 5.5 or GPT-6 Astra cheaper?
Claude Sonnet 5.5 is cheaper for a typical chat (2K input tokens and 500 output tokens). Claude Sonnet 5.5 costs $2 per 1M input tokens and $10 per 1M output tokens, while GPT-6 Astra costs $10 per 1M input tokens and $50 per 1M output tokens.
Which has a bigger context window, Claude Sonnet 5.5 or GPT-6 Astra?
GPT-6 Astra supports up to 1.05M tokens of context, compared with 1M for Claude Sonnet 5.5.
Is Claude Sonnet 5.5 smarter than GPT-6 Astra?
On the Artificial Analysis Intelligence Index, Claude Sonnet 5.5 scores 56 and GPT-6 Astra scores 52.7, putting Claude Sonnet 5.5 ahead. Benchmarks don't capture everything, so the best test is running your own prompts through both.
Can I use Claude Sonnet 5.5 and GPT-6 Astra at the same time?
Yes. Shortcut Chat sends one prompt to multiple models at once, so you can see Claude Sonnet 5.5 and GPT-6 Astra answer side by side and keep the better response.
Why choose? Ask both.
Send one prompt to Claude Sonnet 5.5 and GPT-6 Astra at the same time. Compare the answers side by side and keep the best one.