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GPT-6.1 Terra vs K2 Horizon 375B-A23B

GPT-6.1 Terra leads the LLM Stats Score 47.5 to 38.5.

OpenAI · Institute of Foundation Models · Updated for 2026

Which is better?

GPT-6.1 Terra leads the overall LLM Stats Score 47.5 to 38.5, ranking #36 overall.

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

Choose GPT-6.1 Terra

  • overall performance matters — it scores 47.5 and ranks #36 on LLM Stats
  • your work emphasizes reasoning and coding — it leads those capability indexes
  • you want the most recent training data — it shipped Oct 2026

Choose K2 Horizon 375B-A23B

  • you need open weights you can self-host or fine-tune

At a glance

The differences that matter most.

GPT-6.1 Terra
OpenAI
K2 Horizon 375B-A23B
Institute of Foundation Models
Core performance indexes
LLM Stats Score
47.5
#36
38.5
#83
Reasoning
49.0
#19
37.3
#87
Coding
37.1
#30
21.2
#114
Agents
38.8
#12
23.9
#74
Cost, coverage & limits
Benchmark wins
—
—
Input price
$1.00 / M
— / M
Output price
$5.00 / M
— / M
Context window
1,050,000
—

Capability indexes

Additional strengths measured across groups of related public benchmarks

1 shared
Index
GPT-6.1 Terra
K2 Horizon 375B-A23B
Tool use
33.3#5
22.3#62
Conservative TrueSkill rating · higher is betterHow scores work

Individual benchmarks

8 reported for GPT-6.1 Terra · 18 for K2 Horizon 375B-A23B

No common benchmarks found

GPT-6.1 Terra and K2 Horizon 375B-A23Bdon'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

Context Window

Maximum input and output token capacity

Only GPT-6.1 Terra specifies input context (1,050,000 tokens). Only GPT-6.1 Terra specifies output context (128,000 tokens).

OpenAI
GPT-6.1 Terra
Input1,050,000 tokens
Output128,000 tokens
Institute of Foundation Models
K2 Horizon 375B-A23B
Input- tokens
Output- tokens
Fri Oct 30 2026 • llm-stats.com

Input capabilities

Documented input modalities across available providers

GPT-6.1 Terra supports multimodal inputs, whereas K2 Horizon 375B-A23B does not.

GPT-6.1 Terra can handle both text and other forms of data like images, making it suitable for multimodal applications.

GPT-6.1 Terra

Text
Images
Audio
Video

K2 Horizon 375B-A23B

Text
Images
Audio
Video

License

Usage and distribution terms

GPT-6.1 Terra is licensed under a proprietary license, while K2 Horizon 375B-A23B uses Apache 2.0.

License differences may affect how you can use these models in commercial or open-source projects.

GPT-6.1 Terra

Proprietary

Closed source

K2 Horizon 375B-A23B

Apache 2.0

Open weights

Release Timeline

When each model was launched

GPT-6.1 Terra was released on 2026-10-26, while K2 Horizon 375B-A23B was released on 2026-09-03.

GPT-6.1 Terra is 2 months newer than K2 Horizon 375B-A23B.

GPT-6.1 Terra

Oct 26, 2026

1 days ago

1mo newer
K2 Horizon 375B-A23B

Sep 3, 2026

1 months ago

Knowledge Cutoff

When training data ends

GPT-6.1 Terra has a documented knowledge cutoff of 2026-06-01, while K2 Horizon 375B-A23B's cutoff date is not specified.

We can confirm GPT-6.1 Terra's training data extends to 2026-06-01, but cannot make a direct comparison without K2 Horizon 375B-A23B's cutoff date.

GPT-6.1 Terra

Jun 2026

K2 Horizon 375B-A23B

—

Outputs Comparison

Notice missing or incorrect data?

Judge for yourself.

Run your own prompts against GPT-6.1 Terra and K2 Horizon 375B-A23B side-by-side, then vote on the output you prefer.

GPT-6.1 Terra
✓ Preferred
K2 Horizon 375B-A23B
Open in Playground

FAQ

Common questions about GPT-6.1 Terra vs K2 Horizon 375B-A23B.

Which is better, GPT-6.1 Terra or K2 Horizon 375B-A23B?

GPT-6.1 Terra leads the LLM Stats Score 47.5 to 38.5. GPT-6.1 Terra is made by OpenAI and K2 Horizon 375B-A23B is made by Institute of Foundation Models. The best choice depends on your use case — compare their capability indexes, individual benchmarks, pricing, and limits above.

How does GPT-6.1 Terra compare to K2 Horizon 375B-A23B in benchmarks?

GPT-6.1 Terra scores HealthBench Consensus: 95.1%, HealthBench Professional: 62.7%, Agents' Last Exam: 60.0%, Terminal-Bench-Science 0.1: 58.3%, MentalHealthBench: 55.5%. K2 Horizon 375B-A23B scores GPQA: 87.3%, AA-LCR: 76.0%, OmniScience (non-hallucination rate): 74.7%, BrowseComp: 72.8%, Terminal-Bench 2.1: 70.2%.

What are the context window sizes for GPT-6.1 Terra and K2 Horizon 375B-A23B?

GPT-6.1 Terra supports 1.1M tokens and K2 Horizon 375B-A23B supports an unknown number of tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

What are the main differences between GPT-6.1 Terra and K2 Horizon 375B-A23B?

Key differences include LLM Stats Score (47.5 vs 38.5), multimodal support (yes vs no), licensing (Proprietary vs Apache 2.0). See the full comparison above for benchmark-by-benchmark results.

Who makes GPT-6.1 Terra and K2 Horizon 375B-A23B?

GPT-6.1 Terra is developed by OpenAI and K2 Horizon 375B-A23B is developed by Institute of Foundation Models.

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