Is Grok 4.1 Fast or GPT-5.1-Codex cheaper?

Grok 4.1 Fast is cheaper on output tokens ($0.50 vs $10.00 per 1M).

Which has the larger context window, Grok 4.1 Fast or GPT-5.1-Codex?

Grok 4.1 Fast has the larger context window (2M tokens).

Grok 4.1 Fast vs GPT-5.1-Codex

Grok 4.1 Fast is cheaper on output tokens, while Grok 4.1 Fast offers a larger context window. Choose Grok 4.1 Fast or GPT-5.1-Codex based on the trade-off between cost, context, and the benchmarks that matter for your use case.

Spec	Grok 4.1 Fast	GPT-5.1-Codex
Provider	ZenMux	ZenMux
Input / 1M tokens	$0.20	$1.25
Output / 1M tokens	$0.50	$10.00
Context window	2M	400K
Parameters	—	—
Open weights	No	No
Released	Nov 2025	Nov 2025

Grok 4.1 Fast details →GPT-5.1-Codex details →

FAQ

Pricing is indicative — confirm with the provider before production use. Highlighted values indicate the better figure for that row.