Model Comparison

Gemini 3.1 Pro vs GPT-5.3 Codex

GPT-5.3 Codex significantly outperforms across most benchmarks. GPT-5.3 Codex is 1.2x cheaper per token.

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Performance Benchmarks

Comparative analysis across standard metrics

2 benchmarks

Gemini 3.1 Pro outperforms in 0 benchmarks, while GPT-5.3 Codex is better at 2 benchmarks (SWE-Bench Pro, Terminal-Bench 2.0).

GPT-5.3 Codex significantly outperforms across most benchmarks.

Tue Apr 07 2026 • llm-stats.com

Arena Performance

Human preference votes

Pricing Analysis

Price comparison per million tokens

GPT-5.3 Codex costs less

For input processing, Gemini 3.1 Pro ($2.50/1M tokens) is 1.4x more expensive than GPT-5.3 Codex ($1.75/1M tokens).

For output processing, Gemini 3.1 Pro ($15.00/1M tokens) is 1.1x more expensive than GPT-5.3 Codex ($14.00/1M tokens).

In conclusion, Gemini 3.1 Pro is more expensive than GPT-5.3 Codex.*

* Using a 3:1 ratio of input to output tokens

Lowest available price from all providers
Tue Apr 07 2026 • llm-stats.com
Google
Gemini 3.1 Pro
Input tokens$2.50
Output tokens$15.00
Best providerGoogle
OpenAI
GPT-5.3 Codex
Input tokens$1.75
Output tokens$14.00
Best providerOpenAI
Notice missing or incorrect data?Start an Issue→

Context Window

Maximum input and output token capacity

Gemini 3.1 Pro accepts 1,048,576 input tokens compared to GPT-5.3 Codex's 400,000 tokens. GPT-5.3 Codex can generate longer responses up to 128,000 tokens, while Gemini 3.1 Pro is limited to 65,536 tokens.

Google
Gemini 3.1 Pro
Input1,048,576 tokens
Output65,536 tokens
OpenAI
GPT-5.3 Codex
Input400,000 tokens
Output128,000 tokens
Tue Apr 07 2026 • llm-stats.com

Input Capabilities

Supported data types and modalities

Both Gemini 3.1 Pro and GPT-5.3 Codex support multimodal inputs.

They are both capable of processing various types of data, offering versatility in application.

Gemini 3.1 Pro

Text
Images
Audio
Video

GPT-5.3 Codex

Text
Images
Audio
Video

License

Usage and distribution terms

Both models are licensed under proprietary licenses.

Both models have usage restrictions defined by their respective organizations.

Gemini 3.1 Pro

Proprietary

Closed source

GPT-5.3 Codex

Proprietary

Closed source

Release Timeline

When each model was launched

Gemini 3.1 Pro was released on 2026-02-19, while GPT-5.3 Codex was released on 2026-02-05.

Gemini 3.1 Pro is 0 month newer than GPT-5.3 Codex.

Gemini 3.1 Pro

Feb 19, 2026

1 months ago

2w newer
GPT-5.3 Codex

Feb 5, 2026

2 months ago

Knowledge Cutoff

When training data ends

Gemini 3.1 Pro has a documented knowledge cutoff of 2025-01-31, while GPT-5.3 Codex's cutoff date is not specified.

We can confirm Gemini 3.1 Pro's training data extends to 2025-01-31, but cannot make a direct comparison without GPT-5.3 Codex's cutoff date.

Gemini 3.1 Pro

Jan 2025

GPT-5.3 Codex

—

Provider Availability

Gemini 3.1 Pro is available from Google. GPT-5.3 Codex is available from OpenAI.

Gemini 3.1 Pro

google logo
Google
Input Price:Input: $2.50/1MOutput Price:Output: $15.00/1M

GPT-5.3 Codex

openai logo
OpenAI
Input Price:Input: $1.75/1MOutput Price:Output: $14.00/1M
* Prices shown are per million tokens

Outputs Comparison

Notice missing or incorrect data?Start an Issue discussion→

Key Takeaways

Google
Larger context window (1,048,576 tokens)
OpenAI
Less expensive input tokens
Less expensive output tokens
Higher SWE-Bench Pro score (56.8% vs 54.2%)
Higher Terminal-Bench 2.0 score (77.3% vs 68.5%)

Detailed Comparison

AI Model Comparison Table
Feature
Google
Gemini 3.1 Pro
OpenAI
GPT-5.3 Codex

FAQ

Common questions about Gemini 3.1 Pro vs GPT-5.3 Codex

GPT-5.3 Codex significantly outperforms across most benchmarks. Gemini 3.1 Pro is made by Google and GPT-5.3 Codex is made by OpenAI. The best choice depends on your use case — compare their benchmark scores, pricing, and capabilities above.
Gemini 3.1 Pro scores t2-bench: 99.3%, LiveCodeBench Pro: 96.2%, GPQA: 94.3%, MMMLU: 92.6%, BrowseComp: 85.9%. GPT-5.3 Codex scores SWE-Lancer (IC-Diamond subset): 81.4%, Cybersecurity CTFs: 77.6%, Terminal-Bench 2.0: 77.3%, OSWorld-Verified: 64.7%, SWE-Bench Pro: 56.8%.
GPT-5.3 Codex is 1.4x cheaper for input tokens. Gemini 3.1 Pro costs $2.50/M input and $15.00/M output via google. GPT-5.3 Codex costs $1.75/M input and $14.00/M output via openai.
Gemini 3.1 Pro supports 1.0M tokens and GPT-5.3 Codex supports 400K tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.
Key differences include context window (1.0M vs 400K), input pricing ($2.50 vs $1.75/M). See the full comparison above for benchmark-by-benchmark results.
Gemini 3.1 Pro is developed by Google and GPT-5.3 Codex is developed by OpenAI.