GPT-6 Luna Pro vs Grok 4.20 0309 Reasoning

Price, context window & benchmark comparison

GPT-6 Luna Pro

OpenAI

$0.10 / $0.50

Input / Output · per 1M tokens

Grok 4.20 0309 Reasoning

xAI

$1.25 / $2.50

Input / Output · per 1M tokens

Compare different models

Verdict: GPT-6 Luna Pro is 7.8× cheaper than Grok 4.20 0309 Reasoning on a typical 3:1 input/output mix. GPT-6 Luna Pro has the larger context window (1.1M vs 1M).

	GPT-6 Luna Pro	Grok 4.20 0309 Reasoning
Input price / 1M	$0.10	$1.25
Output price / 1M	$0.50	$2.50
Blended price (3:1)	$0.20	$1.56
Cached input / 1M	$0.01	$0.20
Context window	1.1M	1M
Max output	128K	30K
Intelligence index	—	—
Coding index	—	—
Providers	6	—
Best provider uptime (30m)	100.0%	—
Vision input	Yes	Yes
Reasoning	Yes	Yes
Tool calling	Yes	Yes
Released	2026-09-22	2026-10-16
Retirement	—	—

Cost calculator

Input tokens / requestOutput tokens / requestRequests / day

FAQ

Which is cheaper, GPT-6 Luna Pro or Grok 4.20 0309 Reasoning?

GPT-6 Luna Pro is 7.8× cheaper than Grok 4.20 0309 Reasoning on a typical 3:1 input/output mix.

GPT-6 Luna Pro vs Grok 4.20 0309 Reasoning: which has a bigger context window?

GPT-6 Luna Pro: 1,050,000 tokens. Grok 4.20 0309 Reasoning: 1,000,000 tokens.

How much would 1 million requests cost?

At 2,000 input + 500 output tokens per request: GPT-6 Luna Pro ≈ $450.00, Grok 4.20 0309 Reasoning ≈ $3,750.

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