# Hermes 4 405B

> Hermes 4 405B is an open-weight language model from Nousresearch, released on 26 Aug 2025. It accepts text and generates text, with a 131K-token context window and up to 118K output tokens per response. As of 4 Oct 2026, the lowest listed API price is $1 per million input tokens and $3 per million output tokens (OpenRouter), across 1 provider we track.

Source page: https://www.aimodel.directory/models/hermes-4-405b
Last verified: 4 Oct 2026

## Specifications

- **Developer:** Nousresearch
- **Release date:** 26 Aug 2025 (source: OpenRouter, https://openrouter.ai/nousresearch/hermes-4-405b)
- **Status:** Generally available
- **Weights:** Open weights (source: Hugging Face, https://huggingface.co/NousResearch/Hermes-4-405B)
- **License:** llama3 (source: Hugging Face, https://huggingface.co/NousResearch/Hermes-4-405B)
- **Parameters:** 406B (source: Hugging Face, https://huggingface.co/NousResearch/Hermes-4-405B)
- **Context window:** 131K (131,072 tokens) (source: OpenRouter, https://openrouter.ai/nousresearch/hermes-4-405b)
- **Max output:** 118K tokens (source: OpenRouter, https://openrouter.ai/nousresearch/hermes-4-405b)
- **Knowledge cutoff:** 31 Aug 2024 (source: OpenRouter, https://openrouter.ai/nousresearch/hermes-4-405b)
- **Input:** Text (source: OpenRouter, https://openrouter.ai/nousresearch/hermes-4-405b)
- **Output:** Text (source: OpenRouter, https://openrouter.ai/nousresearch/hermes-4-405b)
- **Reasoning mode:** Yes (source: OpenRouter, https://openrouter.ai/nousresearch/hermes-4-405b)
- **Tool calling:** No (source: OpenRouter, https://openrouter.ai/nousresearch/hermes-4-405b)
- **Structured output:** No (source: OpenRouter, https://openrouter.ai/nousresearch/hermes-4-405b)
- **Hugging Face:** NousResearch/Hermes-4-405B (source: Hugging Face, https://huggingface.co/NousResearch/Hermes-4-405B)

## API pricing (USD per 1M tokens)

| Provider | Input | Output | Cached input | Context |
|---|---|---|---|---|
| OpenRouter | $1 | $3 | – | 131K |

## FAQ

### What is the context window of Hermes 4 405B?

Hermes 4 405B has a context window of 131,072 tokens (131K) and can generate up to 117,964 tokens in a single response, according to OpenRouter.

### How much does the Hermes 4 405B API cost?

Hermes 4 405B is listed from $1 per million input tokens and $3 per million output tokens (OpenRouter). Prices last verified 4 Oct 2026.

### Is Hermes 4 405B open source?

Hermes 4 405B is an open-weight model: its weights are published on Hugging Face as NousResearch/Hermes-4-405B under the llama3 license. Check the license terms before commercial use.

### When was Hermes 4 405B released?

Nousresearch released Hermes 4 405B on 26 Aug 2025, according to OpenRouter.

---
Data licensed CC BY 4.0. Cite as: AI Model Directory, "Hermes 4 405B", https://www.aimodel.directory/models/hermes-4-405b