Grok 4.6 Released: API, Pricing, 500K Context, and Developer Guide

xAI released Grok 4.6 on August 12, 2026. The official developer guide lists the API model ID as grok-4.6, with a 500,000-token context window, text and image input, text output, and four reasoning-effort levels: low, medium, high (default), and xhigh.

For developers, the most important details are not just the launch scorecards. Grok 4.6 works with both the Responses API and Chat Completions, has a long-context pricing boundary at 200,000 prompt tokens, and requires deliberate cache affinity and context management for long-running agents.

This guide separates official xAI specifications from provider-reported benchmark claims and from current Modelflare availability. Prices and availability can change; all volatile facts below were checked on August 13, 2026.

Grok 4.6 at a glance

Property	Official value
Release date	August 12, 2026
API model ID	grok-4.6
Context window	500,000 tokens
Knowledge cutoff	February 1, 2026
Modalities	Text and image input; text output
Text output limit	xAI lists no fixed text output limit
Reasoning effort	low, medium, high (default), xhigh
API formats	Responses API and Chat Completions
Documented capabilities	Function calling, structured outputs, web search, X search, code execution

“No text output limit” is the model-page description, not a promise that every SDK, gateway, account, or request can return unlimited text. Client timeouts, account limits, route policy, and available context still apply.

What changed from Grok 4.5

xAI positions Grok 4.6 as an incremental frontier-model release focused on long-running agents and more ambitious interactive and visual work. Its release post describes longer supplemental training, regenerated supervised fine-tuning trajectories, and agentic reinforcement learning across knowledge work, coding, web development, kernel optimization, and CAD.

The practical changes to evaluate are:

• xhigh joins low, medium, and high reasoning effort;
• xAI reports better continuity across multi-step research, codebase work, and iterative application building;
• the model accepts image input as well as text and returns text;
• the same 500K context class and standard $2 input / $6 output headline rates remain, but Grok 4.6 cached-input pricing is $0.50 per million tokens rather than Grok 4.5’s currently listed $0.30;
• xAI recommends conversation-level cache affinity and context compaction for sustained agent loops.

These are reasons to run a controlled migration, not reasons to replace Grok 4.5 blindly. Compare successful task completion, latency, total tokens, tool calls, and cost on your own workload.

Grok 4.6 API pricing

xAI’s pricing page lists the following standard US-dollar prices per one million tokens:

Prompt size	Input	Cached input	Output
Below 200K prompt tokens	$2.00	$0.50	$6.00
At or above 200K prompt tokens	$4.00	$1.00	$12.00

Once the prompt reaches 200K tokens, xAI says the long-context rates apply to all tokens in that request. Three quick calculations make the boundary concrete:

• 100K input plus 5K output at standard short-context rates costs about $0.23.
• If all 100K input tokens are served from cache, the same output costs about $0.08.
• 220K input plus 10K output crosses the threshold and costs about $1.00 at the listed long-context rates.

These examples exclude server-side tools. xAI currently lists web search, X search, and code execution at $5 per 1,000 calls in addition to token usage. Its launch post also mentions a fast variant priced at twice the standard rate. Confirm the exact model, service tier, regional availability, and live price in the xAI console before budgeting.

For a broader cost method, see How to Calculate AI API Cost and AI API Cost Tracking.

Call Grok 4.6 with Responses or Chat Completions

The following requests use xAI’s official API endpoint, because this article is a release guide—not a claim that the model is already enabled on every gateway.

Responses API:

export XAI_API_KEY="<YOUR_XAI_API_KEY>"

curl -sS https://api.x.ai/v1/responses \
  -H "Authorization: Bearer $XAI_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "grok-4.6",
    "input": "Review this migration plan, identify the three highest-risk assumptions, and propose verification steps.",
    "prompt_cache_key": "grok-46-migration-review"
  }'

Chat Completions:

curl -sS https://api.x.ai/v1/chat/completions \
  -H "Authorization: Bearer $XAI_API_KEY" \
  -H "Content-Type: application/json" \
  -H "x-grok-conv-id: grok-46-migration-review" \
  -d '{
    "model": "grok-4.6",
    "messages": [
      {
        "role": "user",
        "content": "Review this migration plan, identify the three highest-risk assumptions, and propose verification steps."
      }
    ]
  }'

Use prompt_cache_key with Responses or the x-grok-conv-id header with Chat Completions to improve cache affinity for a conversation. Treat those identifiers as operational metadata: keep them stable for one conversation, avoid secrets or personal data, and do not reuse one value across unrelated users.

If you are deciding between the two wire formats, read Responses API vs Chat Completions.

Prompt caching and long agent loops

A 500K context window is capacity, not a target. Sending the full history on every turn can increase latency and can push the entire request into the long-context price tier.

For sustained workflows:

1. keep stable instructions and reusable context at the beginning of the prompt;
2. use a stable cache-affinity key per conversation;
3. measure cached and uncached input separately;
4. compact or summarize old turns before the prompt approaches 200K tokens;
5. retain tool results that are still authoritative and discard duplicated transport noise;
6. set an explicit reasoning level and compare task-level success rather than assuming xhigh is always better;
7. record status, latency, input, cached input, output, tool calls, and total cost per successful task.

Context compaction changes the information the model sees. Validate summaries against the original state and preserve authoritative IDs, constraints, decisions, and unresolved errors.

Read launch benchmarks with the right caveat

xAI published the following Grok 4.6 High results in its launch announcement:

Evaluation	xAI-reported Grok 4.6 score
Artificial Analysis Intelligence Index	61
GDPVal-AA v2	1753
CursorBench v3.2	69.9%
DeepSWE v1.1	65.9%
FrontierCode v1.1 Extended	61.3%
APEX-Agents	57.5%

These are provider-published launch results, not independent Modelflare tests. Benchmark harnesses, reasoning settings, tool access, time limits, and scoring versions affect comparability. Use the table to identify workloads worth testing; do not convert it into a universal quality ranking or a guaranteed production outcome.

Production migration checklist

Before routing production traffic to Grok 4.6:

1. use the exact grok-4.6 model ID and reject silent alias substitution;
2. confirm the model is enabled for the intended account, region, API format, and service tier;
3. replay a fixed, privacy-safe evaluation set on Grok 4.5 and Grok 4.6;
4. test text input, image input, function calling, structured outputs, streaming, refusal paths, and cancellation separately where your application uses them;
5. compare low, medium, high, and xhigh on successful-task cost and latency;
6. test requests immediately below and above the 200K prompt threshold;
7. verify cache hits, context compaction, tool-call counts, retry behavior, and duplicate-side-effect protection;
8. keep a rollback route and log the final model, route, usage, latency, and charge for each request.

An HTTP 200 proves that one request completed. It does not prove feature parity, stable latency, correct tool behavior, or acceptable cost. For route-level testing, use the OpenAI-Compatible API Conformance Tests and Reliable AI API Routing.

Is Grok 4.6 available on Modelflare?

Yes. At the production check on August 13, 2026, Modelflare’s public Models & Pricing catalog listed the exact grok-4.6 model ID in the grok-award and grok-stable groups. The catalog reports support for OpenAI-compatible Chat Completions and Responses API routes.

The group multipliers displayed at that check were 0.03x for grok-award and 0.06x for grok-stable. Group access, routes, prices, and availability can change. Because xAI also applies a separate long-context price tier, do not extend one headline multiplier or short-context example to every request. Treat the live pricing page and the completed request record as the current source of truth.

Create or update an API key with an eligible group, use the exact grok-4.6 ID, and send one real, non-sensitive request before moving production traffic. A catalog listing confirms the configured public surface; it is not an independent quality benchmark or a guarantee for every API key.

Official sources and update log

Primary sources:

• xAI: Introducing Grok 4.6
• xAI developer guide: Grok 4.6
• xAI model page: grok-4.6
• xAI API pricing
• xAI release notes

Update log:

• August 13, 2026: Initial publication. Official specifications, pricing, API formats, launch benchmarks, and Modelflare catalog availability checked.