GLM 5.3 Flash vs GPT-5.1-Codex
Price, context window & benchmark comparison
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Verdict: GLM 5.3 Flash is 69.4× cheaper than GPT-5.1-Codex on a typical 3:1 input/output mix. GLM 5.3 Flash has the larger context window (1M vs 400K).
| GLM 5.3 Flash | GPT-5.1-Codex | |
|---|---|---|
| Input price / 1M | $0.0399 | $1.25 |
| Output price / 1M | $0.0784 | $10.00 |
| Blended price (3:1) | $0.0495 | $3.44 |
| Cached input / 1M | $0.03 | $0.13 |
| Context window | 1M | 400K |
| Max output | 131K | 128K |
| Intelligence index | 27.8 | — |
| Coding index | 71.5 | — |
| Providers | 42 | — |
| Best provider uptime (30m) | 100.0% | — |
| Vision input | Yes | Yes |
| Reasoning | Yes | Yes |
| Tool calling | Yes | Yes |
| Released | 2026-08-26 | 2025-11-13 |
| Retirement | — | — |
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FAQ
Which is cheaper, GLM 5.3 Flash or GPT-5.1-Codex?
GLM 5.3 Flash is 69.4× cheaper than GPT-5.1-Codex on a typical 3:1 input/output mix.
GLM 5.3 Flash vs GPT-5.1-Codex: which has a bigger context window?
GLM 5.3 Flash: 1,048,576 tokens. GPT-5.1-Codex: 400,000 tokens.
How much would 1 million requests cost?
At 2,000 input + 500 output tokens per request: GLM 5.3 Flash ≈ $119.00, GPT-5.1-Codex ≈ $7,500.
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