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GPT-5.1 Codex Mini vs GPT-6 Luna

GPT-6 Luna leads the LLM Stats Score 43.1 to -3.1. GPT-6 Luna is 3.4x cheaper per token.

OpenAI · OpenAI · Updated for 2026

Which is better?

GPT-6 Luna leads the overall LLM Stats Score 43.1 to -3.1, ranking #55 overall.

On price, GPT-6 Luna is roughly 3.4x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.

GPT-6 Luna also accepts a larger context window (1,050,000 input tokens), making it the stronger choice for long documents and large codebases.

Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.

Choose GPT-5.1 Codex Mini

  • you want predictable pricing at $0.25/M input and $2.00/M output

Choose GPT-6 Luna

  • overall performance matters — it scores 43.1 and ranks #55 on LLM Stats
  • your work emphasizes reasoning — it leads those capability indexes
  • cost matters — it's about 3.4x cheaper per token
  • you process long inputs — it offers a 1,050,000 token context window
  • you want the most recent training data — it shipped Sep 2026

At a glance

The differences that matter most.

GPT-5.1 Codex Mini
OpenAI
GPT-6 Luna
OpenAI
Core performance indexes
LLM Stats Score
-3.1
#366
43.1
#55
Reasoning
-3.0
#358
39.9
#69
Cost, coverage & limits
Benchmark wins
—
—
Input price
$0.25 / M
$0.10 / M
Output price
$2.00 / M
$0.50 / M
Context window
400,000
1,050,000

Individual benchmarks

1 reported for GPT-5.1 Codex Mini · 5 for GPT-6 Luna

No common benchmarks found

GPT-5.1 Codex Mini and GPT-6 Lunadon't have any common benchmark datasets to compare. They may have been evaluated on different testing suites.

Human preference

Blind head-to-head votes and playground preference scores

Pricing Analysis

Price comparison per million tokens

GPT-6 Luna costs less

For input processing, GPT-5.1 Codex Mini ($0.25/1M tokens) is 2.5x more expensive than GPT-6 Luna ($0.10/1M tokens).

For output processing, GPT-5.1 Codex Mini ($2.00/1M tokens) is 4.0x more expensive than GPT-6 Luna ($0.50/1M tokens).

In conclusion, GPT-5.1 Codex Mini is more expensive than GPT-6 Luna.*

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

Lowest available price from all providers
Fri Oct 23 2026 • llm-stats.com
OpenAI
GPT-5.1 Codex Mini
Input tokens$0.25
Output tokens$2.00
Best providerOpenAI
OpenAI
GPT-6 Luna
Input tokens$0.10
Output tokens$0.50
Best providerOpenAI
Notice missing or incorrect data?

Context Window

Maximum input and output token capacity

GPT-6 Luna accepts 1,050,000 input tokens compared to GPT-5.1 Codex Mini's 400,000 tokens. Both models can generate responses up to 128,000 tokens.

OpenAI
GPT-5.1 Codex Mini
Input400,000 tokens
Output128,000 tokens
OpenAI
GPT-6 Luna
Input1,050,000 tokens
Output128,000 tokens
Fri Oct 23 2026 • llm-stats.com

Input capabilities

Documented input modalities across available providers

Both GPT-5.1 Codex Mini and GPT-6 Luna support multimodal inputs.

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

GPT-5.1 Codex Mini

Text
Images
Audio
Video

GPT-6 Luna

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.

GPT-5.1 Codex Mini

Proprietary

Closed source

GPT-6 Luna

Proprietary

Closed source

Release Timeline

When each model was launched

GPT-5.1 Codex Mini was released on 2025-11-12, while GPT-6 Luna was released on 2026-09-22.

GPT-6 Luna is 10 months newer than GPT-5.1 Codex Mini.

GPT-5.1 Codex Mini

Nov 12, 2025

11 months ago

GPT-6 Luna

Sep 22, 2026

3 weeks ago

10mo newer

Knowledge Cutoff

When training data ends

GPT-6 Luna has a documented knowledge cutoff of 2026-05-18, while GPT-5.1 Codex Mini's cutoff date is not specified.

We can confirm GPT-6 Luna's training data extends to 2026-05-18, but cannot make a direct comparison without GPT-5.1 Codex Mini's cutoff date.

GPT-5.1 Codex Mini

—

GPT-6 Luna

May 2026

Provider Availability

GPT-5.1 Codex Mini is available from OpenAI. GPT-6 Luna is available from OpenAI.

GPT-5.1 Codex Mini

openai logo
OpenAI
Input Price:Input: $0.25/1MOutput Price:Output: $2.00/1M

GPT-6 Luna

openai logo
OpenAI
Input Price:Input: $0.10/1MOutput Price:Output: $0.50/1M
* Prices shown are per million tokens

Outputs Comparison

Notice missing or incorrect data?

Judge for yourself.

Run your own prompts against GPT-5.1 Codex Mini and GPT-6 Luna side-by-side, then vote on the output you prefer.

GPT-5.1 Codex Mini
✓ Preferred
GPT-6 Luna
Open in Playground

FAQ

Common questions about GPT-5.1 Codex Mini vs GPT-6 Luna.

Which is better, GPT-5.1 Codex Mini or GPT-6 Luna?

GPT-6 Luna leads the LLM Stats Score 43.1 to -3.1. GPT-5.1 Codex Mini is made by OpenAI and GPT-6 Luna is made by OpenAI. The best choice depends on your use case — compare their capability indexes, individual benchmarks, pricing, and limits above.

How does GPT-5.1 Codex Mini compare to GPT-6 Luna in benchmarks?

GPT-5.1 Codex Mini scores AIME 2025: 42.1%. GPT-6 Luna scores DeepSWE 1.1: 66.6%, OSWorld 2.0: 52.7%, Agents' Last Exam: 50.9%, FrontierCode 1.1: 42.4%, AutomationBench v1.0.6: 20.7%.

Is GPT-5.1 Codex Mini cheaper than GPT-6 Luna?

GPT-6 Luna is 2.5x cheaper for input tokens. GPT-5.1 Codex Mini costs $0.25/M input and $2.00/M output via openai. GPT-6 Luna costs $0.10/M input and $0.50/M output via openai.

What are the context window sizes for GPT-5.1 Codex Mini and GPT-6 Luna?

GPT-5.1 Codex Mini supports 400K tokens and GPT-6 Luna supports 1.1M tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

What are the main differences between GPT-5.1 Codex Mini and GPT-6 Luna?

Key differences include LLM Stats Score (-3.1 vs 43.1), context window (400K vs 1.1M), input pricing ($0.25 vs $0.10/M). See the full comparison above for benchmark-by-benchmark results.

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