Is Step 3.5 Flash or GPT-5.1-Codex cheaper?

Step 3.5 Flash is cheaper on output tokens ($0.30 vs $10.00 per 1M).

Which has the larger context window, Step 3.5 Flash or GPT-5.1-Codex?

GPT-5.1-Codex has the larger context window (400K tokens).

Step 3.5 Flash vs GPT-5.1-Codex

Step 3.5 Flash is cheaper on output tokens, while GPT-5.1-Codex offers a larger context window. Choose Step 3.5 Flash or GPT-5.1-Codex based on the trade-off between cost, context, and the benchmarks that matter for your use case.

Spec	Step 3.5 Flash	GPT-5.1-Codex
Provider	ZenMux	ZenMux
Input / 1M tokens	$0.10	$1.25
Output / 1M tokens	$0.30	$10.00
Context window	256K	400K
Parameters	—	—
Open weights	No	No
Released	Feb 2026	Nov 2025

Step 3.5 Flash 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.