AI model comparison
GPT-5.3-Codex vs Gemini 3.1 Pro Preview
Pricing, context window, benchmarks, and features compared side by side. Or skip the guesswork and send one prompt to both.
OpenAI
GPT-5.3-Codex
GPT-5.3-Codex is OpenAI’s most advanced agentic coding model, combining the frontier software engineering performance of GPT-5.2-Codex with the broader reasoning and professional knowledge capabilities of GPT-5.2.
- Input / 1M
- $1.75
- Output / 1M
- $14
- Context
- 400K
Gemini 3.1 Pro Preview
Gemini 3.1 Pro Preview is Google’s frontier reasoning model, delivering enhanced software engineering performance, improved agentic reliability, and more efficient token usage across complex workflows.
- Input / 1M
- $2
- Output / 1M
- $12
- Context
- 1.05M
At a glance
Quick verdict
How the two models stack up on the things people ask about most.
Lower price
Gemini 3.1 Pro Preview
1.1x cheaper for a typical chat
Higher intelligence score
GPT-5.3-Codex
32.5 vs 29.7 on Artificial Analysis
Larger context window
Gemini 3.1 Pro Preview
1.05M vs 400K tokens
Newer release
GPT-5.3-Codex
Released February 24, 2026
Benchmarks
Benchmark scores
Independent scores from Artificial Analysis. Higher is better.
Intelligence index
GPT-5.3-Codex32.5Gemini 3.1 Pro Preview29.7Coding index
GPT-5.3-CodexNot availableGemini 3.1 Pro Preview68.8Agentic index
GPT-5.3-CodexNot availableGemini 3.1 Pro Preview8.2Pricing
GPT-5.3-Codex vs Gemini 3.1 Pro Preview API pricing
Per-token API rates. Cheaper option highlighted.
| Metric | GPT-5.3-Codex | Gemini 3.1 Pro Preview |
|---|---|---|
| Input tokensPer 1M tokens | $1.75 | $2 |
| Output tokensPer 1M tokens | $14 | $12 |
| Cached input (read)Per 1M tokens | $0.18 | $0.20 |
| Cache writePer 1M tokens | Not available | $0.38 |
| Long-context pricingPer 1M tokens, for very long prompts | Same rate at any length | $4 in / $18 out above 200K |
| Web searchPer request | $0.01 | $0.014 |
What it costs in practice
Estimated cost per 1,000 requests at standard rates. Coding and long-document figures also show the cost when the input is already cached.
Chat message
2K in, 500 out
GPT-5.3-Codex$10.50Gemini 3.1 Pro Preview$10Coding task
30K in, 4K out
GPT-5.3-Codex$108.50$61.25 cachedGemini 3.1 Pro Preview$108$54 cachedLong document summary
150K in, 2K out
GPT-5.3-Codex$290.50$54.25 cachedGemini 3.1 Pro Preview$324$54 cachedSpecs
Context window and capabilities
How much each model can read, how much it can write, and what it accepts as input.
| Metric | GPT-5.3-Codex | Gemini 3.1 Pro Preview |
|---|---|---|
| Context window | 400K tokens | 1.05M tokens |
| Max output | 128K tokens | 66K tokens |
| Input types | File, Image, Text | Audio, File, Image, Text, Video |
| Output types | Text | Text |
| Reasoning effort levels | Extra high, High, Medium, Low, None | High, Medium, Low |
| Default reasoning effort | Medium | Medium |
| Release date | February 24, 2026 | February 19, 2026 |
Features
Supported features
API features available for each model.
| Metric | GPT-5.3-Codex | Gemini 3.1 Pro Preview |
|---|---|---|
| Tool calling | Supported | Supported |
| Structured outputs | Supported | Supported |
| JSON mode | Supported | Supported |
| Reasoning | Supported | Supported |
| Temperature | Not supported | Supported |
| Stop sequences | Not supported | Supported |
| Deterministic seed | Supported | Supported |
| Verbosity control | Supported | Not supported |
Keep exploring
More on these models
Other head-to-heads, the full model page, and the alternatives list for each model.
Gemini 3.1 Pro PreviewView full model details- Gemini 3.1 Pro Preview vs Claude Opus 5.5
- Gemini 3.1 Pro Preview vs GPT-6 Astra
- Gemini 3.1 Pro Preview vs GLM 5.2
- Gemini 3.1 Pro Preview vs Gemini 3.5 Flash
- Gemini 3.1 Pro Preview vs Gemini 3 Flash Preview
- Gemini 3.1 Pro Preview vs Claude Opus 4.6
- Gemini 3.1 Pro Preview vs GPT-5.2
- Gemini 3.1 Pro Preview vs Claude Sonnet 4.6
- Gemini 3.1 Pro Preview vs Qwen3.7 Max
- Gemini 3.1 Pro Preview vs Claude Opus 4.5
- Gemini 3.1 Pro Preview vs GPT-5.2-Codex
Our take
Gemini 3.1 Pro Preview is 1.1x cheaper for a typical chat. GPT-5.3-Codex scores higher on the Artificial Analysis Intelligence Index (32.5 vs 29.7). Gemini 3.1 Pro Preview has the larger context window (1.05M vs 400K tokens). The right pick depends on your workload, so the quickest way to settle it is to send the same prompt to both and compare.
FAQ
Frequently asked questions
Is GPT-5.3-Codex or Gemini 3.1 Pro Preview cheaper?
Gemini 3.1 Pro Preview is cheaper for a typical chat (2K input tokens and 500 output tokens). Gemini 3.1 Pro Preview costs $2 per 1M input tokens and $12 per 1M output tokens, while GPT-5.3-Codex costs $1.75 per 1M input tokens and $14 per 1M output tokens.
Which has a bigger context window, GPT-5.3-Codex or Gemini 3.1 Pro Preview?
Gemini 3.1 Pro Preview supports up to 1.05M tokens of context, compared with 400K for GPT-5.3-Codex.
Is GPT-5.3-Codex smarter than Gemini 3.1 Pro Preview?
On the Artificial Analysis Intelligence Index, GPT-5.3-Codex scores 32.5 and Gemini 3.1 Pro Preview scores 29.7, putting GPT-5.3-Codex ahead. Benchmarks don't capture everything, so the best test is running your own prompts through both.
Can I use GPT-5.3-Codex and Gemini 3.1 Pro Preview at the same time?
Yes. Shortcut Chat sends one prompt to multiple models at once, so you can see GPT-5.3-Codex and Gemini 3.1 Pro Preview answer side by side and keep the better response.
Why choose? Ask both.
Send one prompt to GPT-5.3-Codex and Gemini 3.1 Pro Preview at the same time. Compare the answers side by side and keep the best one.