Is GLM-5.1 or GPT-5.5 cheaper?

GLM-5.1 is cheaper on output tokens ($3.50 vs $30.00 per 1M).

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

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

GLM-5.1 vs GPT-5.5

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

Spec	GLM-5.1	GPT-5.5
Provider	FastRouter	FastRouter
Input / 1M tokens	$1.05	$5.00
Output / 1M tokens	$3.50	$30.00
Context window	200K	1.1M
Parameters	754B	—
Open weights	Yes	No
Released	Apr 2026	Apr 2026

GLM-5.1 details →GPT-5.5 details →

FAQ

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