---
title: xAI Grok 4.3 on Amazon Bedrock (June 2026): Mantle Routing and Rate-Card Math
description: On June 15, 2026 xAI Grok 4.3 reached GA on Bedrock Mantle at $1.25/$2.50 per 1M tokens — a 10M-in / 1M-out month costs $15 vs $45 on Claude Sonnet 5. Here is the routing math and what breaks on Converse.
url: https://www.factualminds.com/blog/xai-grok-4-3-aws-bedrock-2026/
datePublished: 2026-08-03T00:00:00.000Z
dateModified: 2026-08-03T00:00:00.000Z
author: palaniappan-p
category: Generative AI
tags: bedrock, xai, grok, cost-optimization, genai, finops, foundation-models
---

# xAI Grok 4.3 on Amazon Bedrock (June 2026): Mantle Routing and Rate-Card Math

> On June 15, 2026 xAI Grok 4.3 reached GA on Bedrock Mantle at $1.25/$2.50 per 1M tokens — a 10M-in / 1M-out month costs $15 vs $45 on Claude Sonnet 5. Here is the routing math and what breaks on Converse.

> **AWS lifecycle notice (June 30, 2026)** — Amazon Bedrock Agents Classic is in maintenance for new customers after **July 30, 2026**. Net-new agent builds should use [Bedrock AgentCore](/blog/amazon-bedrock-agentcore-production/). Full matrix: [lifecycle roundup](/blog/aws-service-lifecycle-updates-june-2026/).

On **June 15, 2026**, AWS [announced](https://aws.amazon.com/about-aws/whats-new/2026/06/grok-amazon-bedrock/) **xAI Grok 4.3** general availability on **Amazon Bedrock**, served through the **Bedrock Mantle** endpoint. Published on-demand list rates: **$1.25 / $2.50 per 1M input/output tokens**, with **$0.20 / 1M cached input** (re-verify on [Bedrock pricing](https://aws.amazon.com/bedrock/pricing/) before you lock a budget).

This is a **third frontier option** on Mantle beside OpenAI GPT-5.6 and Anthropic Claude — not a drop-in for every Converse-based agent you already run. If you standardize on Bedrock for procurement and IAM, Grok 4.3 is worth a routing slot when long context and aggressive input pricing matter more than staying on a Converse-native path.

---

## What changed on June 15, 2026

Per AWS at GA:

| Attribute              | Grok 4.3 on Bedrock                                                         |
| ---------------------- | --------------------------------------------------------------------------- |
| Model ID               | `xai.grok-4.3`                                                              |
| API path               | **Mantle** — Chat Completions / Responses (`bedrock-mantle.REGION.api.aws`) |
| Converse API           | **Not supported**                                                           |
| Context                | **1M tokens**                                                               |
| Reasoning              | Configurable: `none` / `low` / `medium` / `high`                            |
| Regions                | `us-east-1`, `us-east-2`, `us-west-2`                                       |
| Geo / global inference | **Not supported** at GA                                                     |

Implication: teams on `bedrock-runtime` Converse (Agents Classic, many LangChain paths, Bedrock Flows) cannot swap model IDs silently. Mantle is a separate invoke surface — same billing account, different client configuration and IAM actions.

---

## First-party pricing math (not a client silhouette)

No anonymized engagement is cited for Grok 4.3 adoption. The numbers below are **reproducible arithmetic on the published Bedrock rate card** — one illustrative monthly shape, labeled as math.

**Illustrative month:** 10M input tokens + 1M output tokens (agentic production mix with moderate output).

| Model               |             Input $ |            Output $ | Monthly total |
| ------------------- | ------------------: | ------------------: | ------------: |
| **Grok 4.3**        | 10 × $1.25 = $12.50 |   1 × $2.50 = $2.50 |    **$15.00** |
| **GPT-5.6 Terra**   | 10 × $2.20 = $22.00 | 1 × $13.20 = $13.20 |    **$35.20** |
| **Claude Sonnet 5** | 10 × $3.00 = $30.00 | 1 × $15.00 = $15.00 |    **$45.00** |
| **GPT-5.6 Luna**    |  10 × $0.22 = $2.20 |   1 × $1.32 = $1.32 |     **$3.52** |

**Direction:** Grok 4.3 is **−$30.00 / month (−67%)** vs Sonnet 5 and **−$20.20 / month (−57%)** vs Terra on identical token counts. Luna is still ~4× cheaper on this mix — use Luna for high-QPS classification, not as a Grok substitute for 1M-context reasoning lanes.

Download the full comparison: [model-routing-cost-worksheet.csv](https://www.factualminds.com/examples/architecture-blog-2026/grok-4-3-bedrock/model-routing-cost-worksheet.csv).

> **Reproduce this** — Open the [worksheet CSV](https://www.factualminds.com/examples/architecture-blog-2026/grok-4-3-bedrock/model-routing-cost-worksheet.csv) and replace the sample 10M/1M columns with your Cost Explorer / CUR input and output totals. Work the [Mantle gotchas checklist](https://www.factualminds.com/examples/architecture-blog-2026/grok-4-3-bedrock/mantle-gotchas.md) before promoting a lane. Pair with [Bedrock cost optimization: token budgets and model selection](/blog/aws-bedrock-cost-optimization-token-budgets-model-selection/).

---

## Opinionated routing: where Grok 4.3 belongs

**We recommend:** trial Grok 4.3 on **new Mantle-native lanes** that need **long context** (large codebases, multi-document RAG, extended chat history) and where list input cost dominates — **after** a frozen-prompt bakeoff against Terra and Sonnet 5. Keep **Converse-native production** on Sonnet 5 until Mantle migration is explicit. Keep **high-volume thin tasks** on Luna (see [GPT-5.6 Luna & Terra pricing](/blog/openai-gpt-5-6-luna-terra-bedrock-pricing-2026/)). Keep **hardest agentic / governance-heavy** work on Claude Opus 5 where ZDR-default and Guardrails composition matter ([Opus 5 on Bedrock](/blog/claude-opus-5-aws-bedrock-2026/)).

**Trade-off you accept:** lower $/MTok and 1M context vs Mantle-only invoke, no Converse tool path, and xAI-specific behavior you must re-validate on your prompt pack.

| Lane                                             | Lean Grok 4.3       | Lean instead                               |
| ------------------------------------------------ | ------------------- | ------------------------------------------ |
| Long-context doc Q&A, 200K–1M token inputs       | Yes                 | Sonnet 5 if Converse + Guardrails required |
| Everyday mid-tier agents (Mantle-ready)          | Trial after bakeoff | Terra (−20% cut still higher $/MTok)       |
| High-QPS classification / routing                | No                  | Luna                                       |
| Converse Agents Classic / Flows (no Mantle plan) | **No**              | Sonnet 5 or Nova                           |
| Regulated ZDR-default flagship agents            | Cautious            | Opus 5                                     |

For OpenAI-on-Bedrock Mantle patterns (Responses API, Codex context), see [OpenAI models + Codex on Bedrock](/blog/amazon-bedrock-openai-models-codex-managed-agents/).

---

## What broke (pattern): Converse assumptions on a Mantle-only model

> **What broke** — A team pointed an existing Bedrock Converse wrapper at `xai.grok-4.3` and got `ValidationException: model does not support Converse`. Root cause: Grok 4.3 is Mantle-only at GA. Detection: CloudWatch `ModelInvocationError` on `bedrock-runtime` with zero Mantle traffic. Fix: migrate invoke to `bedrock-mantle.REGION.api.aws/openai/v1`, update IAM from runtime-only to Mantle actions, and re-test tool schemas — Chat Completions message format differs from Converse content blocks.

Secondary gotcha: **context-tier pricing**. List rates ($1.25 / $2.50) may apply only below a context threshold; **input cost can roughly double above ~200K tokens** on some Bedrock model cards — verify the xAI row before budgeting a 1M-context lane. See [mantle-gotchas.md](https://www.factualminds.com/examples/architecture-blog-2026/grok-4-3-bedrock/mantle-gotchas.md).

---

## Invoke Grok 4.3 on Mantle

Context: OpenAI Python SDK against Bedrock Mantle, region `us-east-1`, model ID from the Grok 4.3 model card. Auth via Bedrock API key or SigV4 per your path.

```python
# openai>=1.x; OPENAI_BASE_URL=https://bedrock-mantle.us-east-1.api.aws/openai/v1
from openai import OpenAI

client = OpenAI()  # OPENAI_API_KEY + OPENAI_BASE_URL from env

response = client.chat.completions.create(
    model='xai.grok-4.3',
    messages=[
        {'role': 'system', 'content': 'You are a concise support assistant.'},
        {'role': 'user', 'content': 'Classify: billing dispute on invoice #4421.'},
    ],
    # reasoning_effort='medium',  # none | low | medium | high — verify model card
)

print(response.choices[0].message.content)
```

Regions today: `us-east-1`, `us-east-2`, `us-west-2`. **No geo/global inference IDs** — capacity-plan inside those Regions. Converse on `bedrock-runtime` is not an fallback.

---

## What to Do This Week

1. Confirm Grok 4.3 is enabled in your Bedrock model access console for the target Region.
2. Pull last 30 days of Bedrock token usage; split Converse vs Mantle usage types in CUR.
3. Recompute monthly $ with the [worksheet CSV](https://www.factualminds.com/examples/architecture-blog-2026/grok-4-3-bedrock/model-routing-cost-worksheet.csv) at Grok, Terra, Sonnet 5, and Luna rows.
4. Pick **one** long-context lane that is Mantle-ready; freeze 50–100 production prompts; score Grok vs incumbent on pass rate, p95 latency, and **$ / completed task** at `reasoning_effort=none` and `medium`.
5. Check context-tier pricing if any prompt exceeds ~200K input tokens.
6. Update IAM, secrets, and observability dashboards to tag Mantle model IDs — Converse-only Cost Explorer filters will miss Grok spend.
7. If you are net-new on agents post–July 30, 2026, route orchestration to [AgentCore](/blog/amazon-bedrock-agentcore-production/) rather than Agents Classic.

---

## What This Post Doesn't Cover

- A published FactualMinds latency/quality bakeoff of Grok 4.3 vs Sonnet 5 vs Terra on our internal prompt packs (no harness linked yet).
- Batch, Provisioned Throughput, or Priority tier pricing for Grok 4.3 — confirm on the model card; GA notes reference on-demand only.
- xAI first-party API vs Bedrock residency/compliance comparison beyond pointing at AWS procurement consolidation.
- EU / non-US regional availability beyond the three US Regions AWS listed at GA.
- Guardrails + Knowledge Bases composition on the same Converse call path without a proxy layer.

Use the rate card + your CUR. Promote lane-by-lane.

---

## Related reading

- [OpenAI GPT-5.6 Luna & Terra Bedrock Price Cuts (July 2026)](/blog/openai-gpt-5-6-luna-terra-bedrock-pricing-2026/)
- [Claude Opus 5 on AWS Bedrock (July 2026)](/blog/claude-opus-5-aws-bedrock-2026/)
- [Claude Sonnet 5 on AWS (June 2026)](/blog/claude-sonnet-5-aws-bedrock-2026/)
- [AWS Bedrock Cost Optimization: Token Budgets and Model Selection](/blog/aws-bedrock-cost-optimization-token-budgets-model-selection/)
- [Amazon Bedrock + OpenAI Models, Codex & Managed Agents](/blog/amazon-bedrock-openai-models-codex-managed-agents/)
- [Generative AI on AWS](/services/generative-ai-on-aws/) · [Amazon Bedrock services](/services/aws-bedrock/)

## FAQ

### When did Grok 4.3 become available on Amazon Bedrock?
AWS announced general availability on June 15, 2026. The model is available via the Bedrock Mantle endpoint in US East (N. Virginia), US East (Ohio), and US West (Oregon). Model ID: xai.grok-4.3. Confirm the live model card before hardcoding region assumptions.

### What are the on-demand Bedrock rates for Grok 4.3?
As published on the Amazon Bedrock pricing page (verify before budgeting): $1.25 per 1M input tokens, $2.50 per 1M output tokens, and $0.20 per 1M cached input tokens. Long-context tiers may step above ~200K input tokens — re-check the xAI row on aws.amazon.com/bedrock/pricing/ for tier breakpoints.

### Can I invoke Grok 4.3 with the Bedrock Converse API?
No. Grok 4.3 on Bedrock uses the Mantle endpoint with Chat Completions or Responses-style calls — not Converse on bedrock-runtime. Existing Converse-based agents, Flows, and SDK wrappers need a Mantle migration path or a different model.

### Should we replace Claude Sonnet 5 with Grok 4.3 for every agent lane?
No. Grok 4.3 wins on list $/MTok and offers a 1M context window with configurable reasoning effort, but Sonnet 5 remains the safer default when you need Converse-native Guardrails composition, established prompt packs, or Anthropic-specific refusal behavior. Promote Grok lane-by-lane after a frozen-prompt quality bakeoff.

### When should we NOT route production traffic to Grok 4.3 yet?
Hold if (1) your stack is Converse-only and Mantle migration is not scheduled, (2) you have not verified context-tier pricing for prompts above ~200K tokens, (3) the lane is high-volume classification where GPT-5.6 Luna is cheaper and sufficient, (4) you need geo/global inference profiles, or (5) legal has not reviewed xAI provider terms for your data tier.

### What could go wrong after switching invoke paths to Mantle for Grok?
Common failures: IAM policies scoped to bedrock-runtime only (Mantle needs bedrock-mantle permissions), reasoning effort set too high (output token blowout), assuming Converse tool-use schemas work unchanged, and budget alerts that only tag Converse usage types so Grok spend looks artificially low until month-end.

### How does Grok 4.3 compare to GPT-5.6 Terra and Luna on price?
On a 10M input / 1M output monthly mix (published list rates): Grok 4.3 ≈ $15, Terra ≈ $35.20, Luna ≈ $3.52, Claude Sonnet 5 ≈ $45. Luna is cheapest for volume lanes; Grok sits between Luna and Terra on token math but adds 1M context and xAI-specific behavior — compare cost per completed task, not token counts alone.

### Does Grok 4.3 support cross-region inference on Bedrock?
Not at GA. AWS lists us-east-1, us-east-2, and us-west-2 only — no geo or global inference profile IDs on the model card. Plan regional capacity and failover inside those three Regions.

---

*Source: https://www.factualminds.com/blog/xai-grok-4-3-aws-bedrock-2026/*