text model comparison
Claude Opus 5.5 vs Kimi K3.1 Pro
Claude Opus 5.5 and Kimi K3.1 Pro are both current text models, from Anthropic and Moonshot Kimi. Kimi K3.1 Pro is 50% cheaper per 1M input tokens than Claude Opus 5.5, $2 vs $4. On Arena WebDev, Claude Opus 5.5 scores 1810 Elo and Kimi K3.1 Pro 1695 Elo (Arena, measured October 28, 2026). Both accept about 1.05M tokens of context (1,048,576 and 1,000,000).
- Higher Arena WebDev
- Claude Opus 5.51810 Elo against 1695 Elo
- Lower price per 1M input tokens
- Kimi K3.1 Pro$2 against $4
- Longer context window
- Kimi K3.1 Pro1.05M tokens against 1M tokens
- Newer release
- Kimi K3.1 ProOct 2026 against Sep 2026
Data verified November 3, 2026 · Dataset 2026-11-03
Side by side
Claude Opus 5.5 and Kimi K3.1 Pro, line by line
Prices in effect today, compared at the same tier wherever both list one. The better value in each row is highlighted.
| Fact | Claude Opus 5.5 | Kimi K3.1 Pro |
|---|---|---|
| Price | ||
| Price per 1M input tokens | $4 | $2 (better) |
| Price per 1M output tokens | $20 | $10 (better) |
| Independent benchmarks | ||
| Arena WebDev | 1810 Elo (#1 of 45) (better) | 1695 Elo (#6 of 45) |
| Arena Text | 1509 Elo (#2 of 51) | Not measured |
| FrontierMath Tiers 1-3 (v2) | 91.2% (#3 of 42) | Not measured |
| GPQA Diamond | 90.6% (#25 of 41) | Not measured |
| SimpleQA Verified | 72.2% (#5 of 38) | Not measured |
| Specs | ||
| Provider | Anthropic | Moonshot Kimi |
| Release date | September 22, 2026 | October 23, 2026 |
| Access | API only | API only |
| Context window | 1,000,000 tokens | 1,048,576 tokens |
| Max output | 128,000 tokens | Not reported |
| Input | text, image | text, image, video |
| Output | text | text |
Charts
Against every current text model
Where Claude Opus 5.5 and Kimi K3.1 Pro land among the current models of their task, on every independent benchmark, on price and on context.
Where each stands
On Arena WebDev, Claude Opus 5.5 ranks #1 and Kimi K3.1 Pro #6 of 45 current models. Each bar is the share of current models it beats: on score, price and context.
Independent benchmarks
Arena Text
Claude Opus 5.5:#2of 51
1,509 Elo · ahead of 98%
Kimi K3.1 Pro: Not scored
Arena WebDev
Claude Opus 5.5:#1of 45
1,810 Elo · ahead of 100%
Kimi K3.1 Pro:#6of 45
1,695 Elo · ahead of 89%
FrontierMath Tiers 1-3 (v2)
Claude Opus 5.5:#3of 42
91.2% · ahead of 95%
Kimi K3.1 Pro: Not scored
GPQA Diamond
Claude Opus 5.5:#25of 41
90.6% · ahead of 40%
Kimi K3.1 Pro: Not scored
SimpleQA Verified
Claude Opus 5.5:#5of 38
72.2% · ahead of 89%
Kimi K3.1 Pro: Not scored
Price and context
Price per 1M input tokens
Claude Opus 5.5:#43of 52
$4 · cheaper than 14%
Kimi K3.1 Pro:#29of 52
$2 · cheaper than 24%
Price per 1M output tokens
Claude Opus 5.5:#43of 52
$20 · cheaper than 14%
Kimi K3.1 Pro:#34of 52
$10 · cheaper than 25%
Context window
Claude Opus 5.5:#26of 64
1M tokens · longer than 22%
Kimi K3.1 Pro:#11of 64
1.05M tokens · longer than 67%
Quality against price
Claude Opus 5.5 scores 1,509 at $8 (blended price per 1M tokens). The line joins the current models no other beats on both price and Arena Text score; hover any point to name it.
Quality against price: the data
| Model | Provider | Blended price per 1M tokens | Arena Text (Elo) |
|---|---|---|---|
| Gemini 4 Argon | $4 | 1,520 | |
| Claude Opus 5.5 | Anthropic | $8 | 1,509 |
| Muse Wonder | Meta | $8 | 1,507 |
| Claude Fable 5 | Anthropic | $20 | 1,504 |
| Claude Fable 5.1 | Anthropic | $20 | 1,504 |
| Gemini 3.8 Flash | $1.50 | 1,496 | |
| Muse Spark 1.3 | Meta | $2 | 1,495 |
| Claude Opus 5 | Anthropic | $10 | 1,492 |
| Kimi K3 | Moonshot Kimi | $6 | 1,488 |
| GPT-5.6 Sol | OpenAI | $8 | 1,485 |
| Gemini 3.6 Flash | $3 | 1,483 | |
| GPT-5.5 | OpenAI | $11 | 1,482 |
| Claude Opus 4.8 | Anthropic | $10 | 1,482 |
| Qwen3.8-Max | Alibaba Qwen | $3 | 1,482 |
| GPT-6.1 Sol | OpenAI | $4 | 1,481 |
| GLM-5.3 | Z.ai | $2.15 | 1,481 |
| MiMo-V2.6-Pro | Xiaomi MiMo | $0.54 | 1,480 |
| Claude Sonnet 5.5 | Anthropic | $4 | 1,477 |
| GLM-5.3-Flash | Z.ai | $0.24 | 1,477 |
| GPT-6 Astra | OpenAI | $20 | 1,476 |
| DeepSeek-V4.1-Flash | DeepSeek | $0.52 | 1,476 |
| GPT-5.4 | OpenAI | $5.63 | 1,475 |
| Gemini 3 Flash Preview | $1.13 | 1,473 | |
| Grok 4.20 | xAI | $1.56 | 1,472 |
| GPT-5.6 Terra | OpenAI | $4.50 | 1,467 |
| Grok 4.5 | xAI | $3 | 1,465 |
| DeepSeek-V4-Pro | DeepSeek | $1.98 | 1,465 |
| Claude Sonnet 5 | Anthropic | $4 | 1,462 |
| GPT-6 Sol | OpenAI | $4 | 1,458 |
| Gemini 3.5 Flash-Lite | $0.85 | 1,456 | |
| Grok 4.6 | xAI | $3 | 1,455 |
| GPT-5.6 Luna | OpenAI | $0.45 | 1,453 |
| MiMo-V2.6-Flash | Xiaomi MiMo | $0.18 | 1,448 |
| Step 5 Preview | StepFun | $1.43 | 1,448 |
| Grok 4.3 | xAI | $1.56 | 1,442 |
| GPT-6 Luna | OpenAI | $0.20 | 1,441 |
| Grok 4.7 | xAI | $3 | 1,441 |
| Mistral Large 4 | Mistral AI | $1.05 | 1,432 |
| Claude Haiku 5.5 | Anthropic | $0.20 | 1,425 |
| GPT-4.1 | OpenAI | $3.50 | 1,415 |
| Solar Pro 4 | Upstage | $0.52 | 1,388 |
| GPT-4.1 mini | OpenAI | $0.70 | 1,383 |
| GPT-4.1 nano | OpenAI | $0.18 | 1,322 |
Cost
What each costs
Example workloads at each provider's listed rates, then every other rate either one lists. The cheaper figure in each row is highlighted.
The same work, priced
For 10M input and 2M output tokens, Claude Opus 5.5 costs 2.0 times as much as Kimi K3.1 Pro, at each provider's listed rates.
10M input and 2M output tokens
Claude Opus 5.5 costs 2.0× as much
- Claude Opus 5.5
- $80
- Kimi K3.1 Pro
- $40
The same, with 9M of the input tokens cached
Claude Opus 5.5 costs 1.9× as much
- Claude Opus 5.5
- $45.80
- Kimi K3.1 Pro
- $23.80
| Workload or rate | Claude Opus 5.5 | Kimi K3.1 Pro |
|---|---|---|
| Example workloads | ||
| 10M input and 2M output tokens | $80 | $40 (better) |
| The same, with 9M of the input tokens cached | $45.80 | $23.80 (better) |
| The same, through the batch API | $40 | Not listed |
| Other listed rates | ||
| 1M input tokens, cached | $0.20 | $0.20 |
| 1M input tokens, 5-minute cache write | $5 | $2 (better) |
| 1M input tokens, 1-hour cache write | $8 | $4 (better) |
| 1M input tokens, batch | $2 | Not listed |
| 1M output tokens, batch | $10 | Not listed |
| 1M input tokens, Highspeed endpoint | Not listed | $4 |
| 1M output tokens, Highspeed endpoint | Not listed | $20 |
Your own bill will differ. These figures use list prices and example workloads. The AI Model Cost Audit reviews your real usage, shortlists models that score as well for each task for less, and estimates the savings.
Launch price $100, regular price $150
Verdict
When to choose each
Claude Opus 5.5
Where it leads
- Higher Arena WebDev score, 1810 Elo vs 1695 Elo
- Batch pricing, $2 input and $10 output per 1M tokens
Best for
- Long-running agentic coding and knowledge work as the general-purpose default
- Cache-heavy agent loops where the 0.05x read multiplier compounds
Watch out for
- The API effort default is medium here, not high as on Claude Fable 5.1 and Claude Sonnet 5.5, so a like-for-like comparison has to set effort explicitly
- The 4.7-generation tokenizer produces roughly 30% more tokens for the same text than Claude Sonnet 4.6 and earlier, so per-token rates do not compare directly across generations
Kimi K3.1 Pro
Where it leads
- Lower input and output prices, $2 and $10 vs $4 and $20 per 1M tokens
- Accepts video input
Best for
- Long-horizon coding and agent work at mid-tier prices
- Long documents, images and video in one 1M-token context
Watch out for
- Thinking is always on: reasoning effort runs low, high or max, and max is the default
- The Highspeed endpoint, two to three times faster by Moonshot's account, costs twice as much at $4 input and $20 output per 1M tokens
- Weights are promised by 4 November 2026 and were not out on 3 November; Epoch AI and Arena Text have not scored it yet
From benchmark to production
Building on Claude Opus 5.5 or Kimi K3.1 Pro?
Public scores rarely hold on your own data. We test both models on your real tasks, then build the agent or pipeline around the one that wins.
AI Model Cost AuditLaunch price $100, regular price $150What the audit includes
FAQ
Claude Opus 5.5 vs Kimi K3.1 Pro FAQ
Which is cheaper, Claude Opus 5.5 or Kimi K3.1 Pro?
Kimi K3.1 Pro is 50% cheaper per 1M input tokens than Claude Opus 5.5, $2 vs $4. For 10M input and 2M output tokens, Claude Opus 5.5 costs $80 and Kimi K3.1 Pro $40 at standard rates.
Which is cheaper with prompt caching, Claude Opus 5.5 or Kimi K3.1 Pro?
Claude Opus 5.5 charges $0.20 per 1M cached input tokens, 95% below its standard input rate, and Kimi K3.1 Pro $0.20, 90% below. With 9M of 10M input tokens cached and 2M output tokens, Claude Opus 5.5 costs $45.80 and Kimi K3.1 Pro $23.80.
Which scores higher on independent benchmarks, Claude Opus 5.5 or Kimi K3.1 Pro?
Claude Opus 5.5 leads on Arena WebDev, 1810 Elo to 1695 Elo. Scores are independent evaluations, not either vendor's launch figures.
Which has the larger context window, Claude Opus 5.5 or Kimi K3.1 Pro?
Both accept about 1.05M tokens of context (1,048,576 and 1,000,000).
How do Claude Opus 5.5 and Kimi K3.1 Pro differ in features?
Claude Opus 5.5 takes text and image input; Kimi K3.1 Pro takes text, image and video.
Further reading
More on Claude Opus 5.5 and Kimi K3.1 Pro
Articles on Claude Opus 5.5 and Kimi K3.1 Pro
- Kimi K3.1 Pro: Benchmarks, Price and Should You Switch?October 25, 2026
- GDPval-AA Chart Fact-Check: Opus 5.5 vs GPT-6 Astra on CostSeptember 24, 2026
- GPT-6 Sol vs Claude Opus 5.5, Plus Luna: Best Value per TaskSeptember 24, 2026
- Claude Opus 5.5 Benchmarks: What the Chart Shows and HidesSeptember 23, 2026
- Claude Opus 5.5: Tops the Independent Index at a Lower PriceSeptember 23, 2026
Related comparisons
- Claude Haiku 5.5 vs Claude Opus 5.5
- Claude Sonnet 5.5 vs Kimi K3.1 Pro
- Claude Opus 5.5 vs Mistral Large 4
- Claude Sonnet 5 vs Kimi K3.1 Pro
- Claude Opus 5.5 vs Gemini 4 Argon
- DeepSeek-V4.1-Flash vs Kimi K3.1 Pro
- Claude Opus 5.5 vs GPT-6.1 Sol
- Gemini 4 Argon vs Kimi K3.1 Pro
- Claude Opus 5.5 vs Claude Sonnet 5.5
- GLM-5.3 vs Kimi K3.1 Pro
- Claude Fable 5 vs Claude Opus 5.5
- GPT-6 Astra vs Kimi K3.1 Pro
Production evaluation
Choosing between Claude Opus 5.5 and Kimi K3.1 Pro?
Public benchmarks narrow the shortlist. We run both on your own tasks, data and cost limits, then build the routing and review controls to run the winner in production.
- A head-to-head evaluation on your real workload
- Routing between models by cost and difficulty