Model vs model
Claude Opus 5.5 vs Claude Sonnet 5
Claude Opus 5.5 and Claude Sonnet 5 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 Claude Sonnet 5 page.
Short answer
Claude Sonnet 5 gets twice as many messages: up to 125 messages a month on Pro, against up to 62 messages a month for Claude Opus 5.5. Otherwise, only Claude Opus 5.5 can be passed to another model by its maker's safety system and only Claude Sonnet 5 is in the free trial.
Claude Opus 5.5 and Claude Sonnet 5 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 | Claude Sonnet 5 |
|---|---|---|---|
| Free | $0 | Not in the trial | In the one-time trial of 5 messages |
| Pro | $20 a month | Up to 62 a month | Up to 125 a month |
| Max | $50 a month | Up to 200 a month | Up to 400 a month |
| Ultra | $100 a month | Up to 450 a month | Up to 900 a month |
| Studio | $200 a month | Up to 1,000 a month | Up to 2,000 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 Sonnet 5 gets twice as many messages: up to 125 messages a month on Pro, against up to 62 messages a month for Claude Opus 5.5.
Context window
Both take up to 1M tokens of context. 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
Claude Sonnet 5 is in the free trial; Claude Opus 5.5 needs a paid plan.
Where messages go
Both are Claude models, served the same way. Sent to Anthropic directly.
Fact by fact
| Fact | Claude Opus 5.5 | Claude Sonnet 5 |
|---|---|---|
| Context window | 1M tokens | 1M 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 | $2.00 in / $10.00 out per million tokens |
| A typical message at API prices (4,000 tokens in, 700 out) | $0.0300 | $0.0150 |
| A $10 top-up adds | 50 messages | 100 messages |
| Where a message goes | Sent to Anthropic directly. | Sent to Anthropic 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 Anthropic fails before the reply starts (an overload, a server error, a dropped connection), llmwise sends the same request to Claude Sonnet 5 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 Claude Sonnet 5?
From the facts above, not from benchmarks: the rest is how their answers suit your work, which one chat can show you.
Pick Claude Sonnet 5: more messages for the money, up to 125 messages a month on Pro; you can try it in the free trial.
Try Claude Opus 5.5 and Claude Sonnet 5 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 Claude Sonnet 5 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 Claude Sonnet 5 is one pair of models. The page below covers the whole family.
- Claude Opus 5.5: price, limits and messages on every plan
- Claude Sonnet 5: price, limits and messages on every plan
- Claude playground: try Claude online
- Claude Fable 5.1 vs Claude Opus 5.5
- Claude Opus 5.5 vs GPT-6 Astra
- Claude Opus 5.5 vs GPT-6 Sol
- Claude Opus 5.5 vs DeepSeek V4 Pro
- Every model-vs-model page
Both are made by the same company, so they're served the same way.
Questions
Is Claude Opus 5.5 or Claude Sonnet 5 cheaper in llmwise?
Claude Sonnet 5 gets twice as many messages: up to 125 messages a month on Pro, against up to 62 messages a month for Claude Opus 5.5. 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 Claude Sonnet 5 for free?
Claude Sonnet 5 is, in the free trial of 5 messages; Claude Opus 5.5 needs a paid plan.
Which has the bigger context window, Claude Opus 5.5 or Claude Sonnet 5?
Neither: both take 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 Claude Sonnet 5 in the same chat?
Yes. Pick Claude Opus 5.5 for one message and Claude Sonnet 5 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.