Hermes 4 405B: pricing, context and performance

Hermes 4 405B at a glance

Released on August 26, 2025, Hermes 4 405B is one of the 1 Nous Research models tracked on this site. Its weights are published: you can download it and run it on your own servers, or use one of the 5 API providers that list it on models.dev. It has a reasoning mode: it can "think" before answering, which helps with multi-step problems but uses more tokens, and therefore more money. That makes it more than a year old: successors may have shipped since.

We file it under open-weight models (68 models in this category on the site).

Benchmark results

As of October 22, 2026, Epoch AI publishes no score for Hermes 4 405B on our basket's benchmarks. To place it, rely on its specifications and price, then test it on your own cases.

Technical specifications

Its context window reaches 131,072 tokens, roughly 197 pages of text at 500 words per page: enough for a medium-length document. A single answer can run to 8,192 tokens.

It accepts as input: text. Its knowledge stops at August 31, 2024: beyond that, it needs web search or your documents.

It can call tools (functions, APIs) and return structured JSON output, which makes it a possible foundation for an AI agent.

The weights are published on Hugging Face (NousResearch/Hermes-4-405B). See also our list of open-source models.

What it costs

Hermes 4 405B costs $1.00 per million input tokens and $2.99 per million output tokens (median of 5 providers, checked on October 22, 2026).

To put it in perspective: reading 20,000 tokens (about thirty pages) and writing 2,000 costs roughly $0.026; a thousand of those tasks, $25.9.

That is 3 times the median output price of open-weight models ($1).

To estimate your own budget, use the agent cost calculator.

When to choose it

Given its category, Hermes 4 405B is mainly aimed at projects where you want control over your data or hosting, or want to adapt the model to your field.

Before adopting it, test it on your own examples: benchmarks measure standard tasks, not your job.

Comparable models

In the same category, the models closest to Hermes 4 405B are:

• Step 5 Preview (StepFun, $2.99 per million output tokens)
• Kimi K2.5 (Moonshot AI, index 78.1)
• Qwen3.6 27B (Alibaba Cloud (Qwen), index 72.2)
• GLM-5 (Zhipu AI (Z.ai), index 77.2)