# Longest context window LLMs

GPT-6.1 Terra ties for the largest context window of the recent, generally available models in our data: 1,050,000 tokens. Lowest price with a 1M+ token window: Mercury 3. Highest max output: DeepSeek-V4.1-Flash-1017. Open weights with a long window: GLM-5.3. A listed window is a limit, not a measure of how well a model uses it.

Updated: 2026-10-29 · Canonical: https://theagenticweekly.com/best/long-context-llms · Evidence: Reported (not run by us)

## Picks, and the fact behind each

| Pick | Model | Why | Source |
|---|---|---|---|
| Largest published context window | [GPT-6.1 Terra](https://theagenticweekly.com/models/gpt-6-1-terra) | 1,050,000 tokens, tied with 6 other models here (newest shown); $1 in / $5 out per 1M tokens. | [source](https://developers.openai.com/api/docs/models/gpt-6.1-terra) |
| Lowest price with a 1M+ token window | [Mercury 3](https://theagenticweekly.com/models/mercury-3) | 1M tokens at $0.1 in / $0.35 out per 1M tokens (temporary price). | [source](https://www.inceptionlabs.ai/blog/introducing-mercury-3) |
| Highest max output | [DeepSeek-V4.1-Flash-1017](https://theagenticweekly.com/models/deepseek-v4-1-flash-1017) | Up to 384,000 output tokens with a 1M-token window. | [source](https://api-docs.deepseek.com/zh-cn/quick_start/pricing) |
| Open weights with a long window | [GLM-5.3](https://theagenticweekly.com/models/glm-5-3) | 1.05M tokens, weights downloadable (GLM-5.3 License (MIT-style plus a MaaS condition)). | [source](https://huggingface.co/zai-org/GLM-5.3/blob/main/LICENSE) |

## All models in scope

Language models in our data released in the 120 days before Oct 29, 2026 with a published context window of at least 400K tokens. Largest first.

| Model | Vendor | Context | Price (listed) | Licence | Released | Status |
|---|---|---|---|---|---|---|
| [GPT-6.1 Terra](https://theagenticweekly.com/models/gpt-6-1-terra) | OpenAI | 1.05M tokens ([source](https://developers.openai.com/api/docs/models/gpt-6.1-terra)) | $1 in / $5 out per 1M tokens ([source](https://developers.openai.com/api/docs/models/gpt-6.1-terra)) | Proprietary (API) ([source](https://developers.openai.com/api/docs/models/gpt-6.1-terra)) | Oct 26, 2026 ([source](https://developers.openai.com/api/docs/changelog)) | Generally available |
| [GPT-6.1 Sol](https://theagenticweekly.com/models/gpt-6-1-sol) | OpenAI | 1.05M tokens ([source](https://developers.openai.com/api/docs/models/gpt-6.1-sol)) | $2 in / $10 out per 1M tokens ([source](https://developers.openai.com/api/docs/models/gpt-6.1-sol)) | Proprietary (API) ([source](https://developers.openai.com/api/docs/models/gpt-6.1-sol)) | Sep 29, 2026 ([source](https://developers.openai.com/api/docs/changelog)) | Generally available |
| [GPT-6 Luna](https://theagenticweekly.com/models/gpt-6-luna) | OpenAI | 1.05M tokens ([source](https://developers.openai.com/api/docs/models/gpt-6-luna)) | $0.1 in / $0.5 out per 1M tokens ([source](https://developers.openai.com/api/docs/models/gpt-6-luna)) | Proprietary (API) ([source](https://developers.openai.com/api/docs/models/gpt-6-luna)) | Sep 22, 2026 ([source](https://developers.openai.com/api/docs/changelog)) | Generally available |
| [GPT-6 Astra](https://theagenticweekly.com/models/gpt-6-astra) | OpenAI | 1.05M tokens ([source](https://developers.openai.com/api/docs/models/gpt-6-astra)) | $10 in / $50 out per 1M tokens ([source](https://developers.openai.com/api/docs/models/gpt-6-astra)) | Proprietary (API) ([source](https://developers.openai.com/api/docs/models/gpt-6-astra)) | Sep 3, 2026 ([source](https://openai.com/index/gpt-6-astra/)) | Generally available |
| [GPT-5.6 Luna](https://theagenticweekly.com/models/gpt-5-6-luna) | OpenAI | 1.05M tokens ([source](https://developers.openai.com/api/docs/models/gpt-5.6-luna)) | $0.2 in / $1.2 out per 1M tokens ([source](https://developers.openai.com/api/docs/models/gpt-5.6-luna)) | Proprietary (API) ([source](https://developers.openai.com/api/docs/models/gpt-5.6-luna)) | Jul 9, 2026 ([source](https://developers.openai.com/api/docs/changelog)) | Generally available |
| [GPT-5.6 Sol](https://theagenticweekly.com/models/gpt-5-6-sol) | OpenAI | 1.05M tokens ([source](https://developers.openai.com/api/docs/models/gpt-5.6-sol)) | $4 in / $20 out per 1M tokens (promotional price, OpenAI says it is available at least through Nov 21, 2026; list price after the promo not stated) ([source](https://developers.openai.com/api/docs/models/gpt-5.6-sol)) | Proprietary (API) ([source](https://developers.openai.com/api/docs/models/gpt-5.6-sol)) | Jul 9, 2026 ([source](https://developers.openai.com/api/docs/changelog)) | Generally available |
| [GPT-5.6 Terra](https://theagenticweekly.com/models/gpt-5-6-terra) | OpenAI | 1.05M tokens ([source](https://developers.openai.com/api/docs/models/gpt-5.6-terra)) | $2 in / $12 out per 1M tokens ([source](https://developers.openai.com/api/docs/models/gpt-5.6-terra)) | Proprietary (API) ([source](https://developers.openai.com/api/docs/models/gpt-5.6-terra)) | Jul 9, 2026 ([source](https://developers.openai.com/api/docs/changelog)) | Generally available |
| [Kimi K3.1 Pro](https://theagenticweekly.com/models/kimi-k3-1-pro) | Moonshot AI | 1.05M tokens ([source](https://www.kimi.ai/resources/kimi-k3-1-pro-pricing)) | $2 in / $10 out per 1M tokens ([source](https://www.kimi.ai/resources/kimi-k3-1-pro-pricing)) | Not yet published ([source](https://www.kimi.ai/blog/kimi-k3-1-pro)) | Oct 23, 2026 ([source](https://vercel.com/changelog/kimi-k3-1-pro-and-kimi-k3-1-pro-highspeed-are-available-now-in-ai-gateway)) | Generally available |
| [Kimi K3.1 Pro Highspeed](https://theagenticweekly.com/models/kimi-k3-1-pro-highspeed) | Moonshot AI | 1.05M tokens ([source](https://www.kimi.ai/resources/kimi-k3-1-pro-pricing)) | $4 in / $20 out per 1M tokens ([source](https://www.kimi.ai/resources/kimi-k3-1-pro-pricing)) | Not published | Oct 23, 2026 ([source](https://vercel.com/changelog/kimi-k3-1-pro-and-kimi-k3-1-pro-highspeed-are-available-now-in-ai-gateway)) | Generally available |
| [Gemini 4 Argon](https://theagenticweekly.com/models/gemini-4-argon) | Google | 1.05M tokens ([source](https://ai.google.dev/gemini-api/docs/models/gemini-4-argon)) | $2 in / $10 out per 1M tokens (introductory price until Nov 30, 2026; list $4 / $20) ([source](https://ai.google.dev/gemini-api/docs/pricing)) | Proprietary (API) ([source](https://ai.google.dev/gemini-api/docs/pricing)) | Oct 13, 2026 ([source](https://blog.google/innovation-and-ai/models-and-research/gemini-models/introducing-gemini-4-argon/)) | Generally available |
| [Muse Wonder](https://theagenticweekly.com/models/muse-wonder) | Meta | 1.05M tokens ([source](https://dev.meta.ai/docs/models)) | $4 in / $20 out per 1M tokens ([source](https://dev.meta.ai/docs/pricing-rate-limits)) | Proprietary (API) ([source](https://dev.meta.ai/docs/models)) | Oct 12, 2026 ([source](https://about.fb.com/news/2026/10/introducing-muse-wonder-models/)) | Public preview |
| [Gemini 3.8 Flash](https://theagenticweekly.com/models/gemini-3-8-flash) | Google | 1.05M tokens ([source](https://ai.google.dev/gemini-api/docs/models/gemini-3.8-flash)) | $0.75 in / $3.75 out per 1M tokens (temporary price until Dec 31, 2026; list $1.5 / $7.5) ([source](https://ai.google.dev/gemini-api/docs/pricing)) | Proprietary (API) ([source](https://ai.google.dev/gemini-api/docs/pricing)) | Sep 2, 2026 ([source](https://ai.google.dev/gemini-api/docs/changelog)) | Generally available |
| [GLM-5.3](https://theagenticweekly.com/models/glm-5-3) | Z.ai | 1.05M tokens ([source](https://docs.z.ai/guides/llm/glm-5.3)) | $1.4 in / $4.4 out per 1M tokens ([source](https://docs.z.ai/guides/overview/pricing)) | GLM-5.3 License (MIT-style plus a MaaS condition) ([source](https://huggingface.co/zai-org/GLM-5.3/blob/main/LICENSE)) | Aug 14, 2026 ([source](https://z.ai/blog/glm-5.3)) | Generally available |
| [Gemini 3.5 Flash-Lite](https://theagenticweekly.com/models/gemini-3-5-flash-lite) | Google | 1.05M tokens ([source](https://ai.google.dev/gemini-api/docs/models/gemini-3.5-flash-lite)) | Not published | Proprietary (API) ([source](https://ai.google.dev/gemini-api/docs/models)) | Jul 21, 2026 ([source](https://ai.google.dev/gemini-api/docs/changelog)) | Generally available |
| [Gemini 3.6 Flash](https://theagenticweekly.com/models/gemini-3-6-flash) | Google | 1.05M tokens ([source](https://ai.google.dev/gemini-api/docs/models/gemini-3.6-flash)) | Not published | Proprietary (API) ([source](https://ai.google.dev/gemini-api/docs/models)) | Jul 21, 2026 ([source](https://ai.google.dev/gemini-api/docs/changelog)) | Generally available |
| [Mercury 3](https://theagenticweekly.com/models/mercury-3) | Inception | 1M tokens ([source](https://www.inceptionlabs.ai/blog/introducing-mercury-3)) | $0.1 in / $0.35 out per 1M tokens (launch promo, end date not stated; list $0.2 / $0.7) ([source](https://www.inceptionlabs.ai/blog/introducing-mercury-3)) | Proprietary (API) ([source](https://www.inceptionlabs.ai/blog/introducing-mercury-3)) | Oct 19, 2026 ([source](https://www.inceptionlabs.ai/blog/introducing-mercury-3)) | Generally available |
| [MiniMax M3.1 Flash](https://theagenticweekly.com/models/minimax-m3-1-flash) | MiniMax | 1M tokens ([source](https://huggingface.co/MiniMaxAI/MiniMax-M3.1-Flash)) | $0.15 in / $0.6 out per 1M tokens ([source](https://www.minimax.io/blog/minimax-m31f)) | MiniMax Community License ([source](https://huggingface.co/MiniMaxAI/MiniMax-M3.1-Flash/blob/main/LICENSE)) | Oct 19, 2026 ([source](https://www.minimax.io/blog/minimax-m31f)) | Generally available |
| [DeepSeek-V4.1-Flash-1017](https://theagenticweekly.com/models/deepseek-v4-1-flash-1017) | DeepSeek | 1M tokens ([source](https://api-docs.deepseek.com/zh-cn/quick_start/pricing)) | ¥1 in / ¥4 out per 1M tokens; peak: ¥2 / ¥8 ([source](https://api-docs.deepseek.com/zh-cn/quick_start/pricing)) | MIT ([source](https://huggingface.co/deepseek-ai/DeepSeek-V4.1-Flash-1017)) | Oct 17, 2026 ([source](https://api-docs.deepseek.com/news/news261017/)) | Generally available |
| [Muse Spark Open](https://theagenticweekly.com/models/muse-spark-open) | Meta | 1M tokens ([source](https://research.meta.ai/blog/muse-spark-open)) | Not published | Muse Model License (limited commercial terms) ([source](https://huggingface.co/meta-models/Muse-Spark-Open-816B-A42B)) | Oct 15, 2026 ([source](https://research.meta.ai/blog/muse-spark-open)) | Generally available |
| [Claude Haiku 5.5](https://theagenticweekly.com/models/claude-haiku-5-5) | Anthropic | 1M tokens ([source](https://platform.claude.com/docs/en/about-claude/models/overview)) | $0.1 in / $0.5 out per 1M tokens ([source](https://platform.claude.com/docs/en/about-claude/models/overview)) | Proprietary (API) ([source](https://platform.claude.com/docs/en/about-claude/models/overview)) | Oct 7, 2026 ([source](https://www.anthropic.com/news)) | Generally available |
| [Mistral Large 4](https://theagenticweekly.com/models/mistral-large-4) | Mistral AI | 1M tokens ([source](https://docs.mistral.ai/models/mistral-large-4)) | $1.36 in / $4.18 out per 1M tokens ([source](https://docs.mistral.ai/models/mistral-large-4)) | Mistral Ecosystem Open-Weight License (MIT derivative with limits on model-as-a-service) ([source](https://huggingface.co/blog/mistral-large4)) | Oct 6, 2026 ([source](https://mistral.ai/news/mistral-large-4/)) | Public preview |
| [Claude Sonnet 5.5](https://theagenticweekly.com/models/claude-sonnet-5-5) | Anthropic | 1M tokens ([source](https://platform.claude.com/docs/en/about-claude/models/overview)) | $2 in / $10 out per 1M tokens ([source](https://platform.claude.com/docs/en/about-claude/models/overview)) | Proprietary (API) ([source](https://platform.claude.com/docs/en/about-claude/models/overview)) | Sep 28, 2026 ([source](https://www.anthropic.com/news)) | Generally available |
| [Claude Opus 5.5](https://theagenticweekly.com/models/claude-opus-5-5) | Anthropic | 1M tokens ([source](https://platform.claude.com/docs/en/about-claude/models/overview)) | $4 in / $20 out per 1M tokens ([source](https://platform.claude.com/docs/en/about-claude/models/overview)) | Proprietary (API) ([source](https://platform.claude.com/docs/en/about-claude/models/overview)) | Sep 22, 2026 ([source](https://www.anthropic.com/news)) | Generally available |
| [Claude Fable 5.1](https://theagenticweekly.com/models/claude-fable-5-1) | Anthropic | 1M tokens ([source](https://platform.claude.com/docs/en/about-claude/models/overview)) | $10 in / $50 out per 1M tokens ([source](https://platform.claude.com/docs/en/about-claude/models/overview)) | Proprietary (API) ([source](https://platform.claude.com/docs/en/about-claude/models/overview)) | Sep 15, 2026 ([source](https://www.anthropic.com/news)) | Generally available |
| [DeepSeek-V4.1-Flash](https://theagenticweekly.com/models/deepseek-v4-1-flash) | DeepSeek | 1M tokens ([source](https://api-docs.deepseek.com/zh-cn/quick_start/pricing)) | ¥1 in / ¥4 out per 1M tokens; peak: ¥2 / ¥8 ([source](https://api-docs.deepseek.com/zh-cn/quick_start/pricing)) | MIT ([source](https://huggingface.co/deepseek-ai/DeepSeek-V4.1-Flash-1017)) | Sep 10, 2026 ([source](https://api-docs.deepseek.com/updates/)) | Generally available |
| [Claude Mythos 5.1](https://theagenticweekly.com/models/claude-mythos-5-1) | Anthropic | 1M tokens ([source](https://platform.claude.com/docs/en/release-notes/overview)) | $10 in / $50 out per 1M tokens ([source](https://platform.claude.com/docs/en/release-notes/overview)) | Proprietary (API) ([source](https://platform.claude.com/docs/en/about-claude/models/overview)) | Sep 1, 2026 ([source](https://platform.claude.com/docs/en/release-notes/overview)) | Limited access |
| [Claude Opus 5](https://theagenticweekly.com/models/claude-opus-5) | Anthropic | 1M tokens ([source](https://platform.claude.com/docs/en/release-notes/overview)) | $5 in / $25 out per 1M tokens ([source](https://platform.claude.com/docs/en/release-notes/overview)) | Proprietary (API) ([source](https://platform.claude.com/docs/en/about-claude/models/overview)) | Jul 24, 2026 ([source](https://platform.claude.com/docs/en/release-notes/overview)) | Generally available |
| [Kimi K3](https://theagenticweekly.com/models/kimi-k3) | Moonshot AI | 1M tokens ([source](https://www.kimi.com/blog/kimi-k3)) | $3 in / $15 out per 1M tokens ([source](https://platform.kimi.ai/docs/pricing/chat)) | Kimi K3 License (custom) ([source](https://huggingface.co/moonshotai/Kimi-K3)) | Jul 16, 2026 ([source](https://www.kimi.com/blog/kimi-k3)) | Generally available |
| [Grok 4.7](https://theagenticweekly.com/models/grok-4-7) | xAI | 500K tokens ([source](https://docs.x.ai/developers/models/grok-4.7)) | $2 in / $6 out per 1M tokens ([source](https://docs.x.ai/developers/models/grok-4.7)) | Proprietary (API) ([source](https://docs.x.ai/developers/models/grok-4.7)) | Sep 21, 2026 ([source](https://docs.x.ai/developers/release-notes)) | Generally available |
| [Grok 4.6](https://theagenticweekly.com/models/grok-4-6) | xAI | 500K tokens ([source](https://docs.x.ai/docs/release-notes)) | $2 in / $6 out per 1M tokens ([source](https://docs.x.ai/docs/release-notes)) | Proprietary (API) ([source](https://docs.x.ai/docs/models)) | Aug 12, 2026 ([source](https://docs.x.ai/docs/release-notes)) | Generally available |
| [Grok 4.5](https://theagenticweekly.com/models/grok-4-5) | xAI | 500K tokens ([source](https://docs.x.ai/docs/models)) | $2 in / $6 out per 1M tokens ([source](https://docs.x.ai/docs/models)) | Proprietary (API) ([source](https://docs.x.ai/docs/models)) | Jul 8, 2026 ([source](https://docs.x.ai/docs/release-notes)) | Generally available |

## FAQ

**Which LLM has the largest context window?** GPT-6.1 Terra, at 1,050,000 tokens, among recent, generally available models in our data. Others list the same figure; see the table.

**Does a bigger context window mean better long-document answers?** Not by itself. The window is the most a model accepts; how well it finds and uses information deep in a long input varies. We have not measured that.

**What is the cheapest model with a 1M-token window?** Mercury 3: $0.1 in / $0.35 out per 1M tokens (temporary price). Some vendors charge more above a size threshold; check the linked pricing page.

**Did you test these context windows?** No. Context windows are Reported from the vendors' model pages.

## How to cite

Agentic Weekly, "Longest context window LLMs", updated 2026-10-29, https://theagenticweekly.com/best/long-context-llms