Grok 4.5 in 10 Minutes: xAI's Fastest Model, 500K Context, and Build-Mode Integration

Grok 4.5 is xAI's current flagship - the model they recommend for everything from chat to code. It ships with a 500,000-token context window, reasoning, function calling, structured outputs, and a build-mode agent workflow that runs in dedicated cloud environments. At $2.00 / $6.00 per million input/output tokens, it sits in a deliberate pricing tier between Grok 4.3 and the older Grok 4 line.

The video on the DevDigest channel walks through all of this in 10 minutes, from the model selector to real build-mode sessions. This post is the companion: verified specs, pricing, and where it fits against the other xAI models and the competitive landscape.

Official Sources#

What Grok 4.5 Is#

xAI positions Grok 4.5 as the single model you should reach for by default. The models overview page states it plainly: "Use Grok 4.5. It is the most intelligent and fastest model we've built." That is a change from earlier eras when xAI maintained separate product lines - the Grok 4 reasoning tier, Grok 4.3, Grok Code Fast, and the older Grok 4.20. Now the advice converges on one model.

Capabilities at a glance:

• Text and image inputs. Grok 4.5 accepts text and images as input and returns text. Image size is capped at 20 MiB with no stated limit on the number of images per request.
• 500K context window. Large enough for full codebases, long documents, or extended multi-turn sessions. Requests at 200K prompt tokens or above trigger long-context pricing.
• Function calling, structured outputs, and reasoning. All three are documented as supported. This is the same capability set you would expect from a frontier model in 2026, matching the OpenAI and Anthropic APIs on the tool-use checklist.
• Knowledge cut-off of February 1, 2026. Without web search or X search tools enabled, Grok 4.5 has no knowledge of events after that date. The search tools are server-side and must be explicitly turned on per request.

Pricing: Where Grok 4.5 Sits in the xAI Lineup#

Grok 4.5 is priced at a deliberate midpoint. It is more expensive than the utility-tier models but cheaper than the older Grok 4 enterprise bracket. Here is the full current text API pricing, fetched from the xAI models page on July 30, 2026:

The takeaway: Grok 4.5 costs 60% more on input tokens and 140% more on output tokens than Grok 4.3 under 200K. The question is whether the intelligence lift justifies that delta for your workload. For code generation and agentic tasks, xAI's answer is yes - they recommend 4.5 over 4.3 for all code work.

Rate limits for Grok 4.5: 150 requests per second and 50 million tokens per minute. That is enough throughput for CI pipelines and moderate-scale agent fleets without needing a dedicated capacity agreement.

Grok 4.5 vs the Rest of the xAI Fleet#

The xAI model lineup is consolidating. Here is where each model earns its keep:

If you have been using Grok 4 through the API, Grok 4.5 is the direct upgrade path. The API model name is grok-4.5, with grok-4.5-latest and grok-build-latest as aliases that track the newest stable release. Pin to a dated version if your pipeline needs consistency.

Build Mode and Agent Workflows#

The grok-build-latest alias points to grok-build-0.1, xAI's build-mode agent model. This is separate from Grok 4.5 itself but designed to work alongside it. Build mode runs coding agents in dedicated cloud environments with shell access, file operations, and the ability to execute multi-step plans.

The pattern that emerges from the model docs is a two-tier workflow: use Grok 4.5 for planning, reasoning about architecture, and understanding complex codebases, then hand the scoped implementation to the build-mode agent for execution. This is the same split that GPT-5.5 in Codex and Claude Opus 4.7 workflows use - a reasoning model for the hard thinking, a cheaper execution model for the implementation loop.

When to Use Grok 4.5#

Use Grok 4.5 when:

• You need strong general intelligence with fast turnaround. xAI calls it their fastest model alongside describing it as most intelligent.
• You want function calling, structured outputs, and reasoning in one model without switching between endpoints.
• You are building multi-step agent workflows and want the model to plan before the build agent executes.
• You need a 500K context window for repository-scale work.

Consider alternatives when:

• Cost is the primary constraint. Grok 4.3 at $1.25/$2.50 is 37% cheaper on input and 58% cheaper on output, with double the context (1M tokens). For batch processing or high-volume pipelines where the quality delta is small, the savings add up.
• You want the absolute cheapest coding loop. Grok-build-0.1 at $1.00/$2.00 is the budget option for agent execution, though the 256K context may be limiting for large repos.
• You need a coding specialist. Grok Code Fast 1 was purpose-built for agentic coding at 200 tokens per second. It is not on the main pricing page but remains available through coding platforms.
• You are deep in the OpenAI or Anthropic ecosystem. GPT-5.5 Developer Guide and Claude Opus 4.7 have comparable capability profiles and more mature tooling integrations. The right model is often the one your team already has keys for.

Watch the Video#

Grok 4.5 in 10 Minutes on the DevDigest channel walks through the Grok model selector, a live build-mode session, and the function-calling workflow. The screen flow shows what static docs cannot: the latency profile, the UI around build-mode environments, and the pacing of tool-call loops in real time.

FAQ#

What is the difference between Grok 4.5 and Grok 4?#

Grok 4.5 is the current flagship, replacing Grok 4 as xAI's recommended model. It has a 500K context window (Grok 4 had a range depending on the variant), is described as xAI's fastest and most intelligent model, and introduces the build-mode alias (grok-build-latest).

How much does Grok 4.5 cost via the API?#

$2.00 per million input tokens and $6.00 per million output tokens for prompts under 200K tokens. Cached input is $0.30. Prompts at or above 200K tokens are billed at $4.00/$12.00. See the xAI pricing page for the latest.

Does Grok 4.5 support function calling?#

Yes. Function calling, structured outputs, and reasoning are all documented as supported capabilities on the Grok 4.5 model page.

Can Grok 4.5 process images?#

Yes. Grok 4.5 accepts image inputs up to 20 MiB each, in JPG or PNG format, with no stated limit on the number of images per request. It returns text output.

Is Grok 4.5 available through coding platforms like Cursor or Copilot?#

xAI models are integrated into multiple coding platforms. Check the model picker in your editor or agent tool. Availability varies by platform and may lag behind the API release.

Sources#

• xAI Models overview - fetched July 30, 2026
• Grok 4.5 model page - fetched July 30, 2026
• Grok web app - confirmed available July 30, 2026
• YouTube: Grok 4.5 in 10 Minutes - DevDigest channel

Note: The xAI blog and news pages returned 403 on fetch. Pricing and capability data is from the developer docs, which are the authoritative source for API users.

Continue Reading#

• Grok 4: xAI's Most Powerful AI Model - the earlier flagship with benchmarks and the Grok Heavy tier
• Grok Code Fast 1: xAI's Speed-Optimized Coding Model - dedicated coding model at 200 tokens/sec
• GPT-5 Codex: OpenAI's Agentic Coding Model - the OpenAI alternative with its own agent loop
• Claude Opus 4.7 Developer Guide - Anthropic's pricing and capability counterpart
• GPT-5.5 Developer Guide - OpenAI's production field guide for the model