GPT-5.1 Instant vs GPT-5.3 Codex: Specs & Benchmark Comparison
| Characteristic | GPT-5.1 Instant | GPT-5.3 Codex |
|---|---|---|
| Company | OpenAI | OpenAI |
| Release Date | November 11, 2025 | February 5, 2026 |
| Parameters | — | — |
| Multimodal | Yes | Yes |
| Context (input) | 256K | 400K |
| Context (output) | 32K | 128K |
| Input Price / 1M | $0.30 | $1.75 |
| Output Price / 1M | $1.20 | $14.00 |
| Average Score | 0.9 | 0.7 |
Verdict
GPT-5.3 Codex leads in 2 out of 4 comparison categories.
Overall Performance
Both models show comparable average scores: GPT-5.1 Instant — 0.9, GPT-5.3 Codex — 0.7.
API Cost
GPT-5.1 Instant is 10.5x cheaper: input $0.30/1M vs $1.75/1M tokens.
Context Window
GPT-5.3 Codex supports a larger context: 400K vs 256K tokens.
Recency
GPT-5.3 Codex is newer: released 2/5/2026 vs 11/11/2025.
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The GPT-5.1 Instant and GPT-5.3 Codex comparison is updated for 2026. Data includes benchmark results, API pricing, context window size and other specifications. For more detailed information, visit the GPT-5.1 Instant or GPT-5.3 Codex page. See also the complete list of AI model comparisons.