Claude Sonnet 5.5 vs Claude Opus 5.5
Sonnet 5.5 nearly matches Opus 5.5 on most measured work at a lower rate — it even beat Opus on Terminal-Bench 4.0. Pay for Opus when the work is long, open-ended and needs judgement throughout, which Anthropic says is where Opus is clearly stronger.
Choose Claude Sonnet 5.5 if
- Everyday coding and terminal work — 70.6% on Terminal-Bench 4.0 against Opus’s 66.4%.
- Speed.
- High volumes.
Choose Claude Opus 5.5 if
- Long, open-ended work that needs sustained judgement.
- Reviewing large codebases.
- The most dependable answer on hard professional tasks.
Side by side
| Claude Sonnet 5.5 | Claude Opus 5.5 | |
|---|---|---|
| Made by | Anthropic | Anthropic |
| Released | September 2026 | September 2026 |
| Input price, per 1M tokens | $2.30 | $4.60 |
| Output price, per 1M tokens | $11.50 | $23.00 |
| Cached input, per 1M tokens | $0.23 | $0.23 |
| Batch (about half price) | Yes | Yes |
| Context window | 1M tokens | 1M tokens |
| Longest answer | 128K tokens | 128K tokens |
| Reads | Text, Images, PDFs | Text, Images, PDFs |
| Thinks before answering | Yes, adjustable | Always on |
| Open weights | No | No |
| Runs in Sri Lanka | No | No |
Prices are Roar AI’s published rates, live from our price list. Specs are each lab’s own published figures.
What a real job costs
Take 1,000 requests, each about 3,000 tokens in and 1,000 out — a long prompt and a page of answer.
Claude Sonnet 5.5 does the same job for 2.0× less. Models that think before answering spend extra output tokens doing it, so on hard prompts the real gap can be wider than the rates suggest.
Use both, switch any time
On Roar AI both are on the same key and the same monthly invoice. Trying the other one is a one-word change:
client.chat.completions.create(model="claude-sonnet-5-5", …) client.chat.completions.create(model="claude-opus-5-5", …)
Send the same prompts to both for a day and compare the answers on your own work — that settles it faster than any benchmark. Read the docs.