One Sentence, a Spinning Solar System

Forget the benchmarks for a second — look at what it can build. One of xAI's examples: fed a single-sentence prompt, Grok 4.5 generated, end to end, a working three.js solar-system simulator with adjustable speed, realistic orbits and a starfield, plus a HUD. xAI stresses that even a terse prompt yields a fully designed, ready-to-use app.

One natural-language instruction, straight to a complete front-end app with controls that runs in real time. Beyond demos like this, xAI notes it can handle challenging Rust and C / C++ tasks, running end to end from prompt to finished result.

Same Task: One Sentence + One Reference Image, Rebuild a 3D Globe Dashboard

Developer @hqmank ran Grok 4.5 through the same challenge: as with his earlier Fable 5 test, just one sentence of prompt plus one reference image, with the task of rebuilding a Three.js 3D globe dashboard.

In his words: the lighting, glass panels, depth of field and spacing all landed; the Three.js scene rendered correctly on the first try; the front end came out much better than expected. On this task, he rates Grok 4.5 above Opus 4.8, with only Fable 5 ahead.

Where It Actually Ranks on the Coding Tests

Here are xAI's DeepSWE 1.0 numbers. DeepSWE 1.0 is a benchmark that tests how well an AI handles real software-engineering tasks; the score is the share it gets right on a single attempt (pass@1 — one shot only, like an exam where you can't cross out and redo). On this board, Grok 4.5 scores 62.0%, in third place.

A common comparison table from xAI/the ecosystem: Terminal-Bench 2.1, SWE-Bench Multilingual, DeepSWE 1.0, SWE-Bench Pro. The Grok 4.5 column is highlighted; some competitors carry high/max/xhigh tier labels. SWE-Bench Multilingual is a supplementary comparison beyond the five boards on the launch page.

The same launch page lists several other coding-related boards. The framing differs, and so does the ranking — first on some, further back on others:

Why It's Fast and Cheap

Grok 4.5's edge sits squarely on speed and cost. It didn't top the benchmarks, but it pairs a flagship-grade brain with a fast model's output speed and low price.

Token efficiency chart from xAI's launch page: average output tokens on SWE-Bench Pro tasks — Grok 4.5 ~15,954, Opus 4.8 max ~67,020, about a 4.2× gap.

For agentic scenarios, that means longer autonomous runs and more back-and-forth within the same token budget and time.

How They Hammered It Out

How this capability got hammered out. Grok 4.5 was trained on tens of thousands of NVIDIA GB300s (NVIDIA's latest-generation high-performance GPU chips built for large-scale AI training). Beyond piling on compute, xAI says the real work went into filtering and cleaning the data: deduplicating, scoring it for quality, and selecting by domain, so the training data is both broad in coverage and dense in signal.

The reinforcement-learning step spans hundreds of thousands of tasks, centered on multi-step software engineering and graded by a mix of automated scoring and model scoring. Their training architecture is highly asynchronous: one agent can run on its own for hours while tens of thousands of GPUs keep learning.

From Writing Code to Building Excel, PPT and Word

Grok 4.5's abilities aren't limited to code. It's now the default model in Grok Build (xAI's command-line coding tool), and the same skills reach into the Excel, PowerPoint and Word trio.

Outline a 5-slide quarterly business review

Word, PowerPoint and Excel all have official plugins now live, installable from the Microsoft Marketplace.

What It Costs, and Where to Use It Now

Price and access. Grok 4.5 charges $2 per million input tokens and $6 per million output. Add in the token savings above, and the real bill on comparable coding tasks drops another notch.

Compared with the public list prices of same-tier flagships (per million tokens):

On specs, Artificial Analysis records the current context window at 500K tokens (a step down from Grok 4.3's 1M); Musk later said on X that it would "probably be back to 1M next week." Modalities are text + image input, text output.

Where you can use it now: Grok Build, every Cursor plan and the xAI console (console.x.ai) are all live — grab an API key and a few lines of code hook it up. OpenRouter, Hermes Agent and others also came online through launch day.

curl -s https://api.x.ai/v1/responses \
  -H "Authorization: Bearer $XAI_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "grok-4.5",
    "input": "Find and fix the bug, then explain it: function median(a){a.sort();return a[a.length/2]}"
  }'

Artificial Analysis notes a few more specs: cache hits run about $0.5 / million tokens (roughly a 75% discount off list); the per-unit price doubles once input exceeds about 200K tokens; the current context window is 500K tokens (a step down from Grok 4.3's 1M, with Musk saying it may be back to 1M next week or so); vision input and configurable reasoning are retained. Cursor says usage doubled in the first week and stresses that Grok 4.5 and its own Composer series are models of different scale — Composer 2.5 will stay around.

⚠️ For now the EU can't use Grok 4.5 in any xAI product or API; xAI expects to open it up in mid-July. For a while, Grok 4.5 is also free to use in Grok Build and Cursor.

What This Update Actually Brings

Bring it down to different people, and the payoffs available right now are roughly these.

• Solo Developers

  A one-sentence prompt generates a complete, working app outright, shortening the path from idea to demoable prototype; when coding, you can switch straight to it inside Grok Build and Cursor.

• Office Knowledge Workers

  One more agent that can model, draw and write copy on its own: the Word / PowerPoint / Excel plugins are live, handling work like online-research-driven multi-sheet Excel modeling, PPT diagramming and official document writing.

• API Developers

  At $2 / $6 per million tokens, plus roughly 2× token efficiency, the same budget runs more and longer agentic autonomous tasks.

Grok 4.5 pries "smart" apart from "fast and cheap." On the same coding problem, it uses about half the words (tokens — the unit for AI billing and compute) of mainstream flagships, outputs about twice as fast, and costs about a quarter as much.

It's not just coding, either: give it one sentence and it builds a working web app outright; it's now wired into Excel, PPT and Word, able to build tables, draw and write copy on its own. But it didn't top the benchmarks — third on the coding tests. Halving the word count and still getting the job done — how?

The key is the number of detour steps. On the same problem, the old flagship thinks back and forth through many steps, outputting text at each one; Grok 4.5 thinks in fewer steps, so it naturally outputs fewer words.

"Twice as fast" doesn't register; money does. Run three AIs over the same batch of coding tasks and see the average cost per task: