Updated 2026-10-28
Kimi K3.1 Pro vs Claude Opus 5.5
K3.1 Pro vs Claude Opus 5.5: compare 1M context, token prices, Terminal-Bench 4.0, coding agents, caching, and best use cases.
TL;DR
- Both expose a 1M-token context window.
- Claude Opus 5.5 has the higher cited Terminal-Bench 4.0 score: 66.4% versus 65.7% for K3.1 Pro.
- K3.1 Pro is substantially cheaper at Moonshot’s list price: ¥13/¥68 per MTok versus $4/$20 per MTok for Opus 5.5.
- Choose Opus 5.5 for a mature Claude-centric workflow; test K3.1 Pro first when cost, open weights, and long coding agents are priorities.
Specification and price comparison
| Dimension | Kimi K3.1 Pro | Claude Opus 5.5 |
|---|---|---|
| Context window | 1,048,576 tokens | 1M tokens |
| Input / MTok | ¥13 | $4 |
| Output / MTok | ¥68 | $20 |
| Terminal-Bench 4.0 | 65.7% | 66.4% |
| Vision input | Yes | Yes |
| Tool use | Custom and Formula tools | Claude platform tools |
| Open weights | Promised before Nov 4, 2026 | No |
Coding-agent comparison
Moonshot’s K3.1 Pro guide reports 65.7% on Terminal-Bench 4.0 and 61.2% on Kimi Code Bench 3.0 Long-horizon. Anthropic positions Claude Opus 5.5 for long-running agentic coding and knowledge work.
The Terminal-Bench gap is only 0.7 percentage points in the cited table. In a real repository, tool permissions, sandbox reliability, retry policy, context selection, and prompt structure can matter more than that margin.
Decision matrix
| Priority | Better starting point | Why |
|---|---|---|
| Lowest Kimi-region token spend | K3.1 Pro | ¥13/¥68 list price and ¥1.30 cache-hit input |
| Highest cited Terminal-Bench score | Claude Opus 5.5 | 66.4% versus 65.7% |
| Self-hosting after weights ship | K3.1 Pro | Moonshot has promised open weights |
| Claude ecosystem integrations | Claude Opus 5.5 | Existing Claude tooling and platform features |
| High-throughput background coding | K3.1 Pro | Lower list cost; Highspeed option available |
Recommended evaluation plan
- Select 20–50 real tasks from your repository, documents, or support workflow.
- Fix model IDs, tool definitions, timeout, retry budget, context selection, and output limit.
- Record pass@1, retries, latency, input tokens, output tokens, and cost.
- Run failed K3.1 Pro tasks on Opus 5.5 and failed Opus tasks on K3.1 Pro to identify systematic differences.
- Choose by total cost per successful task, not headline benchmark score alone.
Sources and fact check
- Kimi K3.1 Pro model guideMoonshot AI · verified 2026-10-28
- Claude models overview and pricingAnthropic · verified 2026-10-28
- Kimi model inference pricingMoonshot AI · verified 2026-10-28
Frequently asked questions
Is Kimi K3.1 Pro better than Claude Opus 5.5?
Not universally. Claude Opus 5.5 scores 66.4% on the cited Terminal-Bench 4.0 table, while K3.1 Pro scores 65.7% but is cheaper at its listed CNY price. Benchmark your own coding-agent tasks.
Is K3.1 Pro cheaper than Opus 5.5?
At list price, K3.1 Pro is ¥13/MTok input and ¥68/MTok output; Opus 5.5 is $4/MTok input and $20/MTok output. Real comparison depends on exchange rate, provider, cache usage, and output length.
Which model should I use for coding agents?
Start with K3.1 Pro if cost and future open weights matter. Start with Opus 5.5 if you already operate in the Claude ecosystem. Run both on identical repository tasks before standardizing.