Quick answer
Kimi K3.1 Pro is Moonshot AI’s new flagship model, and it gets close to Claude Opus 5.5 for a fraction of the price, but it is not better across the board. It costs $2 per million input tokens and $10 per million output tokens, has a 1 million token context window and is expected to become open weight on 4 November. In WorldofAI’s tests it shines at 3D, front-end and web design, while Opus 5.5 still leads on harder agentic coding, complex reasoning and consistency.
Key takeaways
- Moonshot reports 65.7% on Terminal Bench 4.0, just behind Opus 5.5 at 66.4% and ahead of GPT-6 Astra at 58.2%
- It debuts fourth on the Artificial Analysis Intelligence Index with a score of 55
- In one side-by-side 3D build it finished in 15 minutes for $5.71, against 32 minutes and $17.13 for Opus 5.5
- It is strongest at 3D scenes, Blender work, landing pages and SVG art
- It is weaker at robotics, complex reasoning and consistency, and usage limits are a concern
- Most figures come from Moonshot or the creator, so test it on your own work before switching
🛠️ Practical guides
Ready to put this into practice? These step-by-step guides answer two common follow-up questions:
- How to Work Out the Real Cost of an AI Task Before You Switch Models — a simple sum for comparing what a task really costs on a cheap model versus a premium one, retries included.
- How to Fact-Check an AI Research Report Before You Rely on It — a step-by-step check for long AI reports, like the 114-page one shown in the video, before you act on them.
In this guide
- What is Kimi K3.1 Pro?
- How does Kimi K3.1 Pro score on benchmarks?
- How much does Kimi K3.1 Pro cost?
- What did the hands-on tests show?
- Is Kimi K3.1 Pro better than Claude Opus 5.5?
- Where does Kimi K3.1 Pro fall short?
- Who should try Kimi K3.1 Pro?
- How can you try Kimi K3.1 Pro?
- Watch: the source video
- Frequently asked questions
- The bottom line
Every few weeks a new model claims to match the best paid AI for less money. Most of the time the honest answer is “sometimes”. Kimi K3.1 Pro is one of the more convincing attempts we have seen, so it is worth a closer, calmer look.
This review is based on the latest video from WorldofAI, who ran it through coding, 3D, research and design tests. We pull out what matters if you run a small business or build with AI, and we flag which numbers are the maker’s own.
What is Kimi K3.1 Pro?
Kimi K3.1 Pro is the newest and most capable model from Moonshot AI, the Chinese lab behind the Kimi chatbot. Moonshot describes it as a 3 trillion parameter class model, which simply means it is very large.
- 1 million token context window, enough to read several long documents at once
- Big gains in coding, agent tasks, 3D modelling and financial research over Kimi K3
- A faster K3.1 Pro HighSpeed version that runs two to three times quicker
- Expected to be released as an open-weight model, so others can download and host it
We covered the earlier Kimi K3.1 news in GPT-6.5 Leak? MiniMax M3.1 Flash, Gemini 4 Carbon and Kimi K3.1 Explained. The Pro version is the step up.
🔎 Unconfirmed / rumour: The open-weight release is described as expected on 4 November. Until the weights are actually published, treat that date as a plan, not a promise.
How does Kimi K3.1 Pro score on benchmarks?
Very well for an open-weight model, and close to the paid leaders on several tests. According to the benchmarks shown in the video, it beats Opus 5.5 on 9 of 14 reported tests and GPT-6 Astra on about 10.
| Benchmark | Kimi K3.1 Pro | Claude Opus 5.5 | GPT-6 Astra |
|---|---|---|---|
| Terminal Bench 4.0 (agentic coding) | 65.7% | 66.4% | 58.2% |
| SWE Marathon (long coding tasks) | 51.7 | 46.3 | 42.5 |
| BenchCAD (CAD software) | 92.7% | 96.2% | 95.9% |
| Artificial Analysis Intelligence Index | 55, 4th place | n/a in video | n/a in video |
Moonshot also reports top scores on OfficeQA Pro v2 and SpreadsheetBench 2, which test spreadsheet and financial work. That matters for everyday business tasks like reports and models in Excel.
⚠️ Warning: These are mostly the maker’s own published benchmarks. They are useful as a signal, but they rarely match your exact work. Our guide Build an AI Test Set Before You Change a Business Workflow shows how to check a model on tasks you really do.
How much does Kimi K3.1 Pro cost?
$2 per million input tokens and $10 per million output tokens, with cached input at $0.20 per million. Moonshot says this is cheaper than Kimi K3 at launch.
The creator says it is about 80% cheaper than GPT-6 Astra for front-end work, and that one of his game builds was about five times cheaper than Opus 5.5. Those are his estimates from his own runs.
Price per token is only half the story. A cheaper model that needs three attempts can cost more than a dear one that gets it right first time. Our guide How to Work Out the Real Cost of an AI Task Before You Switch Models walks through the sum.
💡 Tip: If your agent sends the same long instructions every time, the cheap cached input price is where the real savings are. See How to Use Prompt Caching to Cut Your AI Agent Costs.
What did the hands-on tests show?
Strong visual and 3D results, with a few rough edges. Here is what stood out in WorldofAI’s tests.
| Test | What happened |
|---|---|
| Canva-style editor | A simple design editor with movable vector shapes, built quickly |
| Landing page | Smooth scroll animations and tidy typography; a good-looking result |
| Browser games | An open-world samurai game and a zombie shooter with animated enemies. In the shooter, the gun would not fire during the demo |
| 3D horse animation | More natural movement than Opus 5.5 or GPT-6 Astra, in the creator’s view |
| Phone replica in Blender | Modelled in Blender and turned into an interactive web page in about 1 hour 30 minutes for $12.50 |
| 114-page research report | An institutional-style quantum computing report with charts and citations to sources |
| SVG peacock | Detailed animated artwork drawn entirely in code |
| Computer use | Painted a detailed portrait in Microsoft Paint by controlling the computer |
A 114-page report sounds impressive, but length is not accuracy. Before using any long AI report for a decision, follow How to Fact-Check an AI Research Report Before You Rely on It.
Is Kimi K3.1 Pro better than Claude Opus 5.5?
Sometimes, but not overall. The creator’s own answer was “yes and no”, and we agree.
- Where Kimi wins: 3D scenes, Blender work and visual front-end pages, often at a third of the cost
- Where it is close: agentic coding benchmarks and CAD tasks
- Where Opus 5.5 leads: harder real-world agentic coding and going further on detailed scenes, such as a New York skyline test where Opus added more detail but spent more
The clearest example was a 3D pagoda island. Kimi took 15 minutes and $5.71. Opus 5.5 took 32 minutes and $17.13 for a comparable result. That is roughly three times cheaper and twice as fast on that one task.
Against other open models, including DeepSeek V4.1 Flash, GLM 5.3 and Qwen 3.8 Max, Kimi produced the best 3D landmark scene in the video. For how DeepSeek’s cheap model compares, see DeepSeek V4.1 Flash 1017 Tested: How a Cheap Open Model Stacks Up.
Where does Kimi K3.1 Pro fall short?
- Robotics: on a real-world robotics benchmark it completed only about 9% of tasks. Every model struggled, but it trailed the leaders
- Complex reasoning and consistency: results vary more than with Opus 5.5
- Usage limits: the creator called these “definitely concerning”
- Bugs in output: as the zombie game showed, impressive demos can still have broken parts
⚠️ Warning: The creator thanks the Kimi team for a viewer discount and links to Kimi in his description. That does not make his tests wrong, but it is worth knowing when you weigh his enthusiasm.
Who should try Kimi K3.1 Pro?
Kimi K3.1 Pro is worth a test if you build websites, landing pages, 3D or visual content, or run lots of AI tasks where cost adds up.
- Marketers and creators: landing page drafts, SVG graphics and visual mock-ups
- Builders on a budget: first drafts of code that a premium model or a human then checks. Our guide How to Draft With a Cheap AI Model and Refine With a Premium One shows the method
- Teams wanting control: once open weights arrive, you could host it yourself or through a provider of your choice
If your work depends on getting tricky logic right first time, keep your premium model for now and use Kimi alongside it.
Thinking of switching models to save money? Start with our guide to working out the real cost of an AI task, so you compare like with like.
How can you try Kimi K3.1 Pro?
- Kimi chatbot: free to start on the Kimi website
- Kimi API: pay as you go at the prices above, through Moonshot’s developer platform
- Coding plan: a subscription with larger usage limits for coding work
- Open weights: expected later, if the planned release goes ahead
💡 Tip: Before you connect any new model to real work, set a spending limit on the API account. Our guide How to Set an AI API Spending Limit and Usage Alert takes five minutes.
Watch: the source video
What this video covers: Kimi K3.1 Pro’s benchmarks, pricing and access options, then hands-on tests across web design, browser games, 3D and Blender, a long research report, SVG art and computer use, with head-to-head comparisons against Claude Opus 5.5 and GPT-6 Astra.
Video: WorldofAI (@intheworldofai). This summary and the opinions in it are our own. Benchmark figures are Moonshot AI’s or the creator’s, and are labelled as such.
Frequently asked questions
Is Kimi K3.1 Pro free?
You can start for free in the Kimi chatbot. The API is paid, at $2 per million input tokens and $10 per million output tokens.
Is Kimi K3.1 Pro open source?
Not yet. It is expected to become open weight on 4 November, which means the model files can be downloaded. Check that the release has happened before planning around it.
Is Kimi K3.1 Pro better than Claude Opus 5.5?
Not overall. It matches or beats Opus 5.5 on some benchmarks and 3D tasks, but Opus still leads on harder agentic coding, complex reasoning and consistency.
How big is the Kimi K3.1 Pro context window?
1 million tokens, which is enough for several long documents or a large codebase in one go.
What is Kimi K3.1 Pro HighSpeed?
A faster version that runs two to three times quicker, for when responsiveness matters more than squeezing out the best answer.
What is Kimi K3.1 Pro best at?
In WorldofAI’s tests: 3D scenes, Blender projects, landing pages, SVG artwork and front-end web design, all at a low price.
The bottom line
Kimi K3.1 Pro is one of the strongest cheaper alternatives to the premium models so far, especially for visual, 3D and front-end work. It is not an Opus killer, and most of the headline numbers are the maker’s. Your next step: run it on three tasks you already do, compare the total cost and quality, and decide from your own results.
Related posts
- DeepSeek V4.1 Flash 1017 Tested: How a Cheap Open Model Stacks Up
- GPT-6.5 Leak? MiniMax M3.1 Flash, Gemini 4 Carbon and Kimi K3.1 Explained
- How to Draft With a Cheap AI Model and Refine With a Premium One
[…] Sponsorship itself is normal. The problem is paid content that looks like independent testing. We reviewed the model ourselves in Kimi K3.1 Pro Review: Is It Really Cheaper Than Claude Opus 5.5?. […]