Claude Mythos 5.1 vs GPT-6.1 Terra
Claude Mythos 5.1 and GPT-6.1 Terra are closely matched at 44.1 and 47.6 on the LLM Stats Score. GPT-6.1 Terra is 10.0x cheaper per token.
Anthropic · OpenAI · Updated for 2026
Which is better?
Claude Mythos 5.1 and GPT-6.1 Terra are closely matched on the overall LLM Stats Score at 44.1 and 47.6.
In the 1 individual benchmarks reported for both models, Claude Mythos 5.1 wins 1; this is a narrower head-to-head signal than the composite indexes.
On price, GPT-6.1 Terra is roughly 10.0x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
GPT-6.1 Terra 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 Claude Mythos 5.1
- you value its reported benchmark strengths — it wins 1 of 1 exact shared results
Choose GPT-6.1 Terra
- cost matters — it's about 10.0x 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 Oct 2026
At a glance
The differences that matter most.
Individual benchmarks
1 reported for Claude Mythos 5.1 · 9 for GPT-6.1 Terra
Claude Mythos 5.1 outperforms in 1 benchmarks (Terminal-Bench 4.0), while GPT-6.1 Terra is better at 0 benchmarks.
Claude Mythos 5.1 significantly outperforms across most benchmarks.
Human preference
Blind head-to-head votes and playground preference scores
Pricing Analysis
Price comparison per million tokens
For input processing, Claude Mythos 5.1 ($10.00/1M tokens) is 10.0x more expensive than GPT-6.1 Terra ($1.00/1M tokens).
For output processing, Claude Mythos 5.1 ($50.00/1M tokens) is 10.0x more expensive than GPT-6.1 Terra ($5.00/1M tokens).
In conclusion, Claude Mythos 5.1 is more expensive than GPT-6.1 Terra.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
GPT-6.1 Terra accepts 1,050,000 input tokens compared to Claude Mythos 5.1's 1,000,000 tokens. Both models can generate responses up to 128,000 tokens.
Input capabilities
Documented input modalities across available providers
Both Claude Mythos 5.1 and GPT-6.1 Terra support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
Claude Mythos 5.1
GPT-6.1 Terra
License
Usage and distribution terms
Both models are licensed under proprietary licenses.
Both models have usage restrictions defined by their respective organizations.
Proprietary
Closed source
Proprietary
Closed source
Release Timeline
When each model was launched
Claude Mythos 5.1 was released on 2026-09-01, while GPT-6.1 Terra was released on 2026-10-26.
GPT-6.1 Terra is 2 months newer than Claude Mythos 5.1.
Sep 1, 2026
2 months ago
Oct 26, 2026
1 weeks ago
1mo newerKnowledge Cutoff
When training data ends
GPT-6.1 Terra has a documented knowledge cutoff of 2026-06-01, while Claude Mythos 5.1'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 Claude Mythos 5.1's cutoff date.
—
Jun 2026
Provider Availability
Claude Mythos 5.1 is available from Anthropic. GPT-6.1 Terra is available from OpenAI.
Claude Mythos 5.1
GPT-6.1 Terra
Outputs Comparison
Judge for yourself.
Run your own prompts against Claude Mythos 5.1 and GPT-6.1 Terra side-by-side, then vote on the output you prefer.
FAQ
Common questions about Claude Mythos 5.1 vs GPT-6.1 Terra.