Arijit Ghosh Chowdhury

Post Training @SpaceXAI

[Arijit Ghosh Chowdhury @arijitgc]

Life update : I’ve joined xAI as a Member of Technical Staff! Working on post-training and RL 🚀

[Arijit Ghosh Chowdhury @arijitgc]

Don't call it a comeback because we never left

[Artificial Analysis @ArtificialAnlys]

SpaceXAI’s Grok 4.5 scores 54 to place fourth on the Artificial Analysis Intelligence Index following only Fable 5, GPT-5.5, and Opus 4.8. It scores on par with GPT-5.5 in Codex on the Artificial Analysis Coding Agent Index in the Grok Build harness, at much lower cost

Grok 4.5 improves 16 points over Grok 4.3 on the Intelligence Index, bringing SpaceXAI to the intelligence frontier behind only OpenAI and Anthropic, and outperforming all open weights models and notably Google’s Gemini models. Key standout areas of performance are agentic knowledge work and coding.

Grok 4.5 in Grok Build scores 76 on the Artificial Analysis Coding Agent Index, on par with GPT-5.5 (xhigh) in Codex and just below Fable 5 (max) in Claude Code, and at a small fraction of the token usage and price.

Congratulations to @SpaceXAI, @cursor_ai, and @elonmusk on the impressive release!

Key Takeaways:

➤ Grok 4.5 performs very strongly on agentic tasks. Grok 4.5 ranks #4 on GDPval-AA v2 with an Elo of 1543, between Claude Opus 4.8 (1600) and GLM-5.2 (1513). It achieves the top score on 𝜏³-Banking of 33%, above 31% from GPT-5.5 (xhigh), and sits on the cost vs performance Pareto frontier across all three agentic evaluations in the Intelligence Index
➤ Grok 4.5 is one of the most cost efficient models to run for near-frontier intelligence. It costs $0.31 per task on the Artificial Analysis Intelligence Index and $2.59 per task on the Artificial Analysis Coding Agent Index within Grok Build
➤ Low cost for Grok 4.5 is driven by both low pricing and token efficiency. Grok 4.5 has a headline price over 60% lower than Claude Opus 4.8 and GPT-5.5, and used ~14k output tokens per Intelligence Index Task - over 60% lower than Opus 4.8. On the Coding Agent Index, Grok 4.5 stands out on the Pareto frontier of Coding Agent Index score vs. Total Tokens, using only 1.9M tokens for the Coding Agent Index while scoring 76
➤ As a coding agent, Grok 4.5 in Grok Build is on par with GPT-5.5 and offers efficiency benefits: In our Artificial Intelligence Coding Agent Index that consists of DeepSWE, Terminal-Bench v2, and SWE-Atlas QnA, Grok 4.5 in Grok Build ranks third, on par with GPT-5.5 (Codex) and below Fable 5 (Claude Code). It is also very efficient in achieving this result: Grok 4.5 in Grok Build cost $2.49 per task while Fable 5 in Claude Code cost $11.80 and GPT-5.5 in Codex $5.07. This is driven by relatively low token pricing and the model using far fewer tokens than comparable models (1.9M average tokens used per task), significantly less than Fable 5 in Claude Code (7.2M) and GPT-5.5 in Codex (6.2M)

Other model details:

➤ Context window of 500k tokens - a reduction from Grok 4.3’s 1M token context, but retaining configurable reasoning and vision input

➤ Pricing of $2/$6 per 1M tokens of input/output; cache hits are discounted by 75% to $0.5 per 1M tokens, and costs still double with long (>200k token) inputs

➤ As Elon Musk has disclosed, Grok 4.5 is 3x larger than its predecessor at 1.5T parameters

[Aditya Gupta @adityagupta]

Not just a new point on pushing the frontier.

We feel we built a model we think can take on and go beyond most of your workload, at a fraction of the cost. Higher intelligence per dollar than any competitor.

And it's a real leap over our last generation. With our model factory we can iterate fast now, so tell us what it's still missing.

[Arijit Ghosh Chowdhury @arijitgc]

It's a good model

[SpaceXAI @SpaceXAI]

Announcing Grok 4.5, our first model trained specifically for coding and agents. It was trained with Cursor and offers frontier intelligence at leading speeds and cost efficiency.

https://t.co/i8HpU7w64k

[Dustin Tran @dustinvtran]

Believe in the length penalty. Parallel vs sequential tools, tool vs base model capability, single agent vs subagents, thinking strategy, truncation, doomlooping, exploration. You don't need new rewards, you need a better length penalty.

[Arijit Ghosh Chowdhury @arijitgc]

@dustinvtran Congratulations Dustin!!

[MTS @MTSlive]

Grok 4.3 stands out for being the most intelligent model in its price range

[Arijit Ghosh Chowdhury @arijitgc]

@JaidevShah4 @GoogleDeepMind Congratulations 🚀

[SpaceXAI @SpaceXAI]

An early beta of Grok Build, an agentic CLI for coding, building apps, and automating workflows is now available for SuperGrok Heavy subscribers.

Through this early beta, we will improve the model and product based on your feedback.

Try it at https://t.co/bpTHpjivWD

[Arijit Ghosh Chowdhury @arijitgc]

@SeongsikKi5837 @thinkymachines Love it!!

[Arijit Ghosh Chowdhury @arijitgc]

@jshobrook You are so wise @jshobrook

[Arijit Ghosh Chowdhury @arijitgc]

@mycharmspace All the best Tianyi!

[Arijit Ghosh Chowdhury @arijitgc]

@Shreyagupta08 Best way to learn something new stuff is trying it out with a few thousand gb300s

[Sarvam @SarvamAI]

We are excited to announce that Sarvam is partnering with @PixxelSpace to power the AI backbone of India's first orbital data centre satellite.

This is a first for the country, with India-built AI models running on an India-built satellite and both training and inference happening directly in orbit, without any dependence on foreign cloud or ground infrastructure.

[Arijit Ghosh Chowdhury @arijitgc]

Pareto frontier on intelligence v cost.
Lots more to come

[Artificial Analysis @ArtificialAnlys]

This release shows increased cost efficiency to run the Artificial Analysis Intelligence Index, with Grok 4.3 sitting comfortably on the Pareto frontier for intelligence versus cost

Driven by 37.5% lower input token prices and 58.3% lower output token prices, it costs $395 to run the Intelligence Index evaluations, an overall ~20% decrease from Grok 4.20 0309 v2

[Arijit Ghosh Chowdhury @arijitgc]

Needed to hear this

[Bryan Johnson @bryan_johnson]

go to bed
right now
i know the build is almost finished
the eval can wait til morning
the agent will still be failing tomorrow
you won't figure out why it's hallucinating
yes your coworker ships on 4 hrs of sleep
they also hallucinate a lot
off you go

[Arijit Ghosh Chowdhury @arijitgc]

@hsu_byron @xai @periodiclabs Congratulations!

[Dylan Patel @dylan522p]

SpaceXAICursor IPO gonna be crazy

[Arijit Ghosh Chowdhury @arijitgc]

@_arohan_ Congratulations!

[Neil @neilshroff]

haan sir ladka nikal gaya hai training data collect kar ke aata hi hoga