Model vs model
Claude Opus 5.5 vs GPT-6 Astra
Claude Opus 5.5 and GPT-6 Astra are both in llmwise. What each gets on every plan, what it reads, how it's served and what happens when its provider fails, from the catalog and the code that runs them.
Model prices and specs checked against OpenRouter's Claude Opus 5.5 page, OpenRouter's GPT-6 Astra page.
Short answer
Claude Opus 5.5 gets twice as many messages: up to 62 messages a month on Pro, against up to 31 messages a month for GPT-6 Astra. Otherwise, only Claude Opus 5.5 can be passed to another model by its maker's safety system.
Claude Opus 5.5 and GPT-6 Astra on every plan
Whether the one-time free trial reaches each model, then each paid plan's messages on it.
| Plan | Price | Claude Opus 5.5 | GPT-6 Astra |
|---|---|---|---|
| Free | $0 | Not in the trial | Not in the trial |
| Pro | $20 a month | Up to 62 a month | Up to 31 a month |
| Max | $50 a month | Up to 200 a month | Up to 100 a month |
| Ultra | $100 a month | Up to 450 a month | Up to 225 a month |
| Studio | $200 a month | Up to 1,000 a month | Up to 500 a month |
Prices don't include tax, which is added where it applies and shown before you pay. A paid plan's month is one allowance shared by every model, so each monthly count is the most you get if all of it goes to that model. It renews each billing period; everyday models refill daily at 00:00 UTC. Long chats count more per reply. How pricing works.
Every limit is published. Paid plans also have a monthly fair-use limit on AI cost: Pro $7.50, Max $20, Ultra $42, Studio $85. Using every message on your plan at typical sizes stays under it; very large messages and heavy research use it faster. Every limit, explained.
What differs
Messages on Pro
Claude Opus 5.5 gets twice as many messages: up to 62 messages a month on Pro, against up to 31 messages a month for GPT-6 Astra.
Context window
Claude Opus 5.5 takes up to 1M tokens; GPT-6 Astra up to 1.05M tokens. A chat in llmwise holds up to 200k tokens, which fits in either, so the difference shows only through each maker's own API.
Images and PDFs
Both read images. Both take a PDF as the whole file, pages and all.
On Free
Neither is in the free trial: both need a paid plan.
Where messages go
Claude Opus 5.5: Sent to Anthropic directly. GPT-6 Astra: Sent to OpenAI directly.
Fact by fact
| Fact | Claude Opus 5.5 | GPT-6 Astra |
|---|---|---|
| Context window | 1M tokens | 1.05M tokens |
| Reads images | Yes | Yes |
| PDFs | Whole file | Whole file |
| Reasoning | Yes | Yes |
| API price (September 2026) | $4.00 in / $20.00 out per million tokens | $10.00 in / $50.00 out per million tokens |
| A typical message at API prices (4,000 tokens in, 700 out) | $0.0300 | $0.0750 |
| A $10 top-up adds | 50 messages | 25 messages |
| Where a message goes | Sent to Anthropic directly. | Sent to OpenAI directly. |
| If the provider fails | If Anthropic fails before the reply starts (an overload, a server error, a dropped connection), llmwise sends the same request to Claude Opus 5.5 through OpenRouter instead. | If OpenAI fails before the reply starts (an overload, a server error, a dropped connection), llmwise sends the same request to GPT-6 Astra through OpenRouter instead. |
| Anthropic's safety fallback | Anthropic's safety system can pass a Claude Opus 5.5 message to another Claude model. The reply then names the model that answered and says what you were charged for. | Doesn't apply |
Claude Opus 5.5 or GPT-6 Astra?
From the facts above, not from benchmarks: the rest is how their answers suit your work, which one chat can show you.
Pick Claude Opus 5.5: more messages for the money, up to 62 messages a month on Pro.
Try Claude Opus 5.5 and GPT-6 Astra on your own question
Start a chat on Claude Opus 5.5 and ask a real question from your work, with any files it needs.
Switch the model picker to GPT-6 Astra and ask for its answer to the same question. It sees the whole chat, including Claude Opus 5.5's answer.
Compare the two on what matters to you: accuracy, tone, length, how much you'd have to fix. If it's close, ask each a follow-up.
The badge by each model in the picker shows what a message uses before you send it.
Each model's page, the families, and other pairs
Claude Opus 5.5 vs GPT-6 Astra is one pair of models. The page below covers the whole families.
- Claude Opus 5.5: price, limits and messages on every plan
- GPT-6 Astra: price, limits and messages on every plan
- GPT vs Claude
- Claude Fable 5.1 vs Claude Opus 5.5
- Claude Opus 5.5 vs Claude Sonnet 5
- Claude Opus 5.5 vs GPT-6 Sol
- Claude Opus 5.5 vs DeepSeek V4 Pro
- Claude Fable 5.1 vs GPT-6 Astra
- GPT-6 Astra vs GPT-6 Sol
- GPT-6 Astra vs Grok 4.7
- Every model-vs-model page
Claude Opus 5.5 is a Claude model; GPT-6 Astra is a GPT model.
Questions
Is Claude Opus 5.5 or GPT-6 Astra cheaper in llmwise?
Claude Opus 5.5 gets twice as many messages: up to 62 messages a month on Pro, against up to 31 messages a month for GPT-6 Astra. Every paid plan's monthly allowance is shared by all models, so each count is the most you get if it all goes to that model.
Can I try Claude Opus 5.5 and GPT-6 Astra for free?
Neither is in the free trial of 5 messages: both need a paid plan, from Pro.
Which has the bigger context window, Claude Opus 5.5 or GPT-6 Astra?
GPT-6 Astra: 1.05M tokens, against 1M tokens. A chat in llmwise holds up to 200k tokens, which fits in either, so the difference shows only through each maker's own API.
Can I use Claude Opus 5.5 and GPT-6 Astra in the same chat?
Yes. Pick Claude Opus 5.5 for one message and GPT-6 Astra for the next; the second sees the whole chat, including the first one's answer.
Claude, GPT, Gemini, DeepSeek, Grok, Kimi, and GLM, in one chat.
See what a message costs before you send it. Free is 5 messages to try; sign in with an email link, no password or card.