Gemini 1.5 Flash vs GPT-5.1-Codex
Google vs OpenAI — benchmarks, pricing, and capabilities side by side.
- •GPT-5.1-Codex has the higher intelligence index (88.2 vs 61.9)
- •Gemini 1.5 Flash is cheaper ($0.15 vs $1.25 per 1M input)
- •GPT-5.1-Codex is faster
- •Gemini 1.5 Flash has a larger context window (1M)
| Gemini 1.5 Flash | GPT-5.1-Codex | |
|---|---|---|
| Intelligence index | 61.9 | 88.2 |
| Developer | OpenAI | |
| Type | Multimodal | Multimodal |
| Access | API only | API only |
| Context window | 1,048,576 tokens | 400,000 tokens |
| Input price | $0.15 / 1M | $1.25 / 1M |
| Output price | $0.60 / 1M | $10.00 / 1M |
| Speed | 150 tok/s | 188 tok/s |
| Released | May 1, 2024 | November 13, 2025 |
| Parameters | — | — |
| Input modalities | — | Text, Image |
| Output modalities | — | Text |
Shared benchmarks
Gemini 1.5 Flash
GPT-5.1-Codex
GPQA Diamond
51
86
Humanity’s Last Exam
4.2
23.4
LiveCodeBench
27.3
84.9
MMLU-Pro
67.3
86