Z.ai: GLM 5.3 Flash vs OpenAI: GPT-5.1-Codex
z-ai vs openai
On price, Z.ai: GLM 5.3 Flash is cheaper (blended cost is about 0.07× that of OpenAI: GPT-5.1-Codex).
On capability, Z.ai: GLM 5.3 Flash has the higher intelligence index (28) — better for complex reasoning.
Verdict: pick Z.ai: GLM 5.3 Flash on a budget, or Z.ai: GLM 5.3 Flash for output quality. Full details below.
Side-by-Side Specs
| Metric | Z.ai: GLM 5.3 Flash | OpenAI: GPT-5.1-Codex |
|---|---|---|
| Input /1M | $0.15 | $1.25 |
| Output /1M | $0.50 | $10.00 |
| Blended (3:1) | $0.24 | $3.44 |
| Context | 1.0M | 400K |
| Intelligence | 28 | 24 |
| Coding | 72 | 37 |
| Math | — | 96 |
| Speed | 56 tok/s | 125 tok/s |
| CPS Grade | A | A |
FAQ
Which is cheaper, Z.ai: GLM 5.3 Flash or OpenAI: GPT-5.1-Codex?
On price, Z.ai: GLM 5.3 Flash is cheaper (blended cost is about 0.07× that of OpenAI: GPT-5.1-Codex). Z.ai: GLM 5.3 Flash: $0.15 in / $0.5 out; OpenAI: GPT-5.1-Codex: $1.25 in / $10 out (per 1M tokens).
Which is smarter, Z.ai: GLM 5.3 Flash or OpenAI: GPT-5.1-Codex?
On capability, Z.ai: GLM 5.3 Flash has the higher intelligence index (28) — better for complex reasoning. Coding index: Z.ai: GLM 5.3 Flash 72 vs OpenAI: GPT-5.1-Codex 37.
Which one should I choose?
Verdict: pick Z.ai: GLM 5.3 Flash on a budget, or Z.ai: GLM 5.3 Flash for output quality. Full details below.