Is GPT-5.5 Instant or GPT-5.1-Codex cheaper?

GPT-5.1-Codex is cheaper on output tokens ($10.00 vs $30.00 per 1M).

Which has the larger context window, GPT-5.5 Instant or GPT-5.1-Codex?

Both models offer a similar context window.

GPT-5.5 Instant vs GPT-5.1-Codex

GPT-5.1-Codex is cheaper on output tokens. Choose GPT-5.5 Instant or GPT-5.1-Codex based on the trade-off between cost, context, and the benchmarks that matter for your use case.

Spec	GPT-5.5 Instant	GPT-5.1-Codex
Provider	ZenMux	ZenMux
Input / 1M tokens	$5.00	$1.25
Output / 1M tokens	$30.00	$10.00
Context window	400K	400K
Parameters	—	—
Open weights	No	No
Released	May 2026	Nov 2025

GPT-5.5 Instant 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.