Claude Instant 1.2vsClaude Mythos 5.1
Claude Instant 1.2 | Claude Mythos 5.1 | |
|---|---|---|
| Specifications | ||
Context windowHow much text the model can hold in mind at once — your question, any documents you attach, the conversation so far, and its own reply. Go past it and the earliest part falls out of view. | 100k | 1M |
| BenchmarksPublished by one model only | ||
HumanEvalFunction synthesis — 164 small Python problems: the AI is given a function's description and has to write the working function. This was the coding benchmark of the GPT-3.5 and GPT-4 era, before the field moved to fixing real bugs in real repositories. Higher is better. | 58.7% | — |
Terminal-Bench 4.0Agentic terminal coding — Can the AI work in a command-line terminal — running commands and finishing technical setup tasks the way a developer would? Version 4.0 recalibrated how much time, CPU and memory each task gets, removed eight tasks and fixed nineteen, so fewer runs fail for reasons that have nothing to do with the model. Scores are not comparable with earlier versions. Higher is better. | — | 60.9% |
GSM8KGrade-school math — Grade-school maths word problems that take a few steps of arithmetic to work through. It separated the models of 2022 and 2023 sharply, then saturated. One caveat on the historical numbers: OpenAI included part of the GSM8K training set in GPT-4's pre-training mix, so GPT-4's score is not a clean few-shot result. Higher is better. | 86.7% | — |
| Overview | ||
| Company | Anthropic | Anthropic |
| Release date | Aug 9 2023 | Sep 1 2026 |
| Access | Proprietary | Proprietary |
Other comparisons
Claude Instant 1.2vsGPT-5.6 SolClaude Mythos 5.1vsGPT-5.6 SolClaude Instant 1.2vsGemini 3.7 FlashClaude Mythos 5.1vsGemini 3.7 FlashClaude Instant 1.2vsMuse GlimmerClaude Mythos 5.1vsMuse GlimmerClaude Instant 1.2vsGrok 4.6Claude Mythos 5.1vsGrok 4.6Claude Instant 1.2vsDeepSeek-V4-Pro-0813Claude Mythos 5.1vsDeepSeek-V4-Pro-0813Claude Instant 1.2vsMistral Medium 3.5Claude Mythos 5.1vsMistral Medium 3.5
Frequently asked questions
Claude Instant 1.2 and Claude Mythos 5.1 don't publish scores on any of the same benchmarks, so there's no direct head-to-head comparison. Claude Instant 1.2 shipped 1119 days before Claude Mythos 5.1, so benchmark comparisons should account for the intervening progress.
Context windows are 100k (Claude Instant 1.2) vs 1M (Claude Mythos 5.1).
Direct benchmark comparisons are unavailable — Claude Instant 1.2 and Claude Mythos 5.1 don't publish scores on any of the same benchmarks.
Claude Instant 1.2 was released by Anthropic on Aug 9 2023.
Claude Mythos 5.1 was released by Anthropic on Sep 1 2026.
Claude Instant 1.2 has a 100k context window; Claude Mythos 5.1 has 1M.