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

GPT-5.1 Codex is cheaper on output tokens ($8.50 vs $180.00 per 1M).

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

GPT-5.5 Pro has the larger context window (1.1M tokens).

GPT-5.1 Codex vs GPT-5.5 Pro

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

Spec	GPT-5.1 Codex	GPT-5.5 Pro
Provider	OpenCode Zen	OpenCode Zen
Input / 1M tokens	$1.07	$30.00
Output / 1M tokens	$8.50	$180.00
Context window	400K	1.1M
Parameters	—	—
Open weights	No	No
Released	Nov 2025	Apr 2026

GPT-5.1 Codex details →GPT-5.5 Pro details →

FAQ

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