Model vs model
Claude Opus 5.5 vs Kimi K3.1 Pro
Claude Opus 5.5 scores higher on the Artificial Analysis Intelligence Index (57.6 vs 55.1), but costs 2× as much: $8 per 1M tokens blended against $4 for Kimi K3.1 Pro. Pick Kimi K3.1 Pro for high-volume work where cost matters, and Claude Opus 5.5 when quality matters most. The biggest gap is on Humanity's Last Exam (hard reasoning), where Claude Opus 5.5 scores 61.4 against 52.5 for Kimi K3.1 Pro.
At a glance
Longer bar means the bigger number.
Blended price · per 1M tokens, lower is better
Intelligence Index · Artificial Analysis, higher is better
Where they sit among all 31 models
Claude Opus 5.5 ranks 1st of the 30 models with an Intelligence Index, Kimi K3.1 Pro 3rd. Up and to the left is smarter for less money. Hover or tap a dot for its numbers, then click it to compare that model with Claude Opus 5.5.
Which one to pick
Pick Claude Opus 5.5 if
- you want the higher overall score (57.6 vs 55.1)
- you care about Humanity's Last Exam (hard reasoning): 61.4 vs 52.5
- you care about SciCode (scientific coding): 66.9 vs 60.8
- you need to send PDFs
Pick Kimi K3.1 Pro if
- you want the lower bill ($4 vs $8 per 1M tokens blended)
- you care about Terminal-Bench 4.0 (terminal tasks): 67.2 vs 59.6
- you want open weights you can run yourself
How smart is each one?
Of the 10 scores both models have, Claude Opus 5.5 is ahead on 8 and Kimi K3.1 Pro on 2.
Every intelligence score we have
Out of 100, higher is better. Claude Opus 5.5 Kimi K3.1 Pro
Overall
Intelligence Index
57.655.1
By field of work
Finance & accounting
60.756.5Legal
63.355.8Healthcare & medicine
54.7Kimi K3.1 Pro: not scored yet
Economics
65.660Engineering
60.455.9Strategy & operations
63.759.4
Benchmarks
Factual knowledge · SimpleQA
72.2Kimi K3.1 Pro: not scored yet
Hard reasoning · Humanity's Last Exam
61.452.5Scientific coding · SciCode
66.960.8Terminal tasks · Terminal-Bench 4.0
59.667.2Long documents · AA-LCR
84.7 · 86.3Uncensored · UGI
54.5Kimi K3.1 Pro: not scored yet
Our tests
Hallucination test · our test, higher means it made up less
99.1Kimi K3.1 Pro: not scored yet
The specs
| Spec | Claude Opus 5.5 | Kimi K3.1 Pro |
|---|---|---|
| Input price | $4 per 1M | $2 per 1M |
| Output price | $20 per 1M | $10 per 1M |
| Context window | 1M | 1.05M |
| Max output | 128K | 1.05M |
| Accepts | Text, Image, PDF | Text, Image |
| Open weights | No | Yes |
| Lab | Anthropic | Kimi |
| Released | Sep 2026 | Oct 2026 |
| Knowledge cutoff | Jun 2026 | Not published |
Blended price weighs 3 parts input to 1 part output. List prices from models.dev.
Questions
Is Claude Opus 5.5 or Kimi K3.1 Pro cheaper?
Kimi K3.1 Pro is cheaper. It charges $2 per 1M input tokens and $10 per 1M output tokens, against $4 and $20 for Claude Opus 5.5. Blended 3 parts input to 1 part output, that is $4 against $8 per 1M tokens.
Which is smarter, Claude Opus 5.5 or Kimi K3.1 Pro?
Claude Opus 5.5 scores higher on the Artificial Analysis Intelligence Index, 57.6 against 55.1 for Kimi K3.1 Pro. The biggest differences are on Humanity's Last Exam (61.4 vs 52.5) and Terminal-Bench 4.0 (59.6 vs 67.2).
Which has the longer context window?
They are about the same: Claude Opus 5.5 accepts 1M tokens and Kimi K3.1 Pro 1.05M.
Can I compare Claude Opus 5.5 and Kimi K3.1 Pro on my own prompt?
Yes. ModelCompare sends one prompt to both models at once and shows each answer side by side with what it cost. You can try it free without an account.
Related comparisons
Where the numbers come from
Intelligence Index and benchmark scores are from Artificial Analysis, at each model’s highest effort, except SimpleQA, which is from Epoch AI, and the Uncensored score, which is from the UGI Leaderboard. The hallucination test is ours: questions with one exact answer, fake evidence pushed against right answers and requests that tempt a model to name packages that don’t exist. Prices are list prices from models.dev. Example answers come from our own test runs. Updated October 23, 2026.