1stTop pick
Researched 57d agoGPT-5.6 Sol
- Context
- 1.05m
- Output (from)
- $30.00 / 1M
Best LLMs for Retrieval-Augmented Generation (2026)
Last refreshed 2026-09-03. Next refresh: weekly.
Best LLMs for RAG in 2026 — ranked by context window, retrieval benchmarks, and tool support. Covers document QA to enterprise search.
Verdict
Use GPT-5.6 Sol for RAG today.
GPT-5.6 Terra is the runner-up: 1.05m vs 1.05m on Context.
2ndShortlist
Researched 57d agoGPT-5.6 Terra
- Context
- 1.05m
- Output (from)
- $15.00 / 1M
3rdShortlist
Researched 57d agoGPT-5.6 Luna
- Context
- 1.05m
- Output (from)
- $6.00 / 1M
How we rank
RAG picks emphasize the strongest sourced long-document benchmark among tracked RAG needles, QA, and retrieval suites, then context window, then recency.
- Eligibility — Models tagged for the RAG decision task (collections/specialization fit or scores on RULER, ZeroSCROLLs, InfiniteBench, multi-needle, MS MARCO, SQuAD, NaturalQuestions, TriviaQA, etc.).
- Primary ranking — Best score across the RAG benchmark bundle, then larger declared context window, then newer release.
- Variant collapse — We keep one row per model family (`familySlug` + parameter tier). When headline scores tie within ±0.5 pt (±10 Elo on Chatbot Arena), we pick the canonical SKU by lowest tracked input price, then GA over preview or limited access, then newest `release`. A folded sibling within the benchmark noise band can show a "Tied within margin" chip on that score cell.
- Pricing — Lowest tracked provider input/output where present.
| # | Model | Input $/1M | Output $/1M | |
|---|---|---|---|---|
| 1 | Nemotron 3 Super-120B-A12B Signal used: RULER 96.33% | $0.09 | $0.45 | |
| 2 | Llama 4 Scout 17B-16E Instruct Vision Signal used: Context 10m | $0.08 | $0.22 | |
| 3 | Gemini 1.5 Pro Signal used: Context 2m | $1.25 | $5.00 | |
| 4 | GPT-6 Astra RestrictedReasoningVisionTools Signal used: Context 1.05m | — | — | |
| 5 | GPT-5.6 Sol ReasoningVisionTools Signal used: Context 1.05m | $5.00 | $30.00 | |
| 6 | GPT-5.6 Terra ReasoningVisionTools Signal used: Context 1.05m | $2.50 | $15.00 | |
| 7 | GPT-5.6 Luna ReasoningVisionTools Signal used: Context 1.05m | $1.00 | $6.00 | |
| 8 | GPT-5.5 ReasoningVisionTools Signal used: Context 1.05m | $5.00 | $30.00 | |
| 9 | GPT-5.5 Pro ReasoningVisionTools Signal used: Context 1.05m | $30.00 | $180.00 | |
| 10 | GPT-5.4 ReasoningVisionTools Signal used: Context 1.05m | $2.50 | $15.00 | |
| 11 | GPT-5.4 Pro ReasoningVisionTools Signal used: Context 1.05m | $30.00 | $180.00 | |
| 12 | Muse Spark 1.3 ReasoningVisionTools Signal used: Context 1.05m | $1.25 | $4.25 | |
| 13 | Muse Spark 1.3 Contributor ReasoningVisionTools Signal used: Context 1.05m | $0.10 | $0.20 | |
| 14 | Gemini 3.8 Flash ReasoningVisionTools Signal used: Context 1.05m | $0.75 | $3.75 | |
| 15 | Spark X2.5 4B ReasoningTools Signal used: Context 1.05m | — | — | |
| 16 | Spark X2.5 1.7B ReasoningTools Signal used: Context 1.05m | — | — | |
| 17 | Hunyuan Hy4 Preview PreviewReasoningTools Signal used: Context 1.05m | $0.83 | $2.50 | |
| 18 | Gemini 3.7 Flash ReasoningVisionTools Signal used: Context 1.05m | $0.75 | $3.75 | |
| 19 | Muse Spark 1.2 PreviewReasoningVisionTools Signal used: Context 1.05m | $1.25 | $4.25 | |
| 20 | Gemini 3.6 Flash ReasoningVisionTools Signal used: Context 1.05m | $1.50 | $7.50 |
Honorable mentions
Next seats in this ranking. Lines below are from each model's stored description in LLMReference seed data—spot-check the model page before relying on a capability claim.
- #4GPT-5.5
GPT-5.5 is OpenAI's fully retrained agentic model, released April 23, 2026. Optimised for agentic coding, computer use, knowledge work, and early scientific research. Achieves 82.7% on Terminal-Bench 2.0 (Codex CLI scaffold), 84.9% on GDPval, 58.6% on SWE-Bench Pro, 93.6% on GPQA Diamond, and 82.6% on SWE-Bench Verified (Vals.ai independent harness). Knowledge cutoff December 2025. Supports reasoning effort levels (none/low/medium/high/xhigh). Context window 1,050,000 tokens with a long-context surcharge above 272K tokens. Model ID: gpt-5.5.
1.05m
Context
GPT-5.5 Pro is OpenAI's premium extra-compute deployment of GPT-5.5, released April 23, 2026. It uses the same underlying weights as GPT-5.5 standard with additional parallel test-time compute for harder tasks. Supports text and image inputs, reasoning effort control, tool use, structured outputs, code execution, a 1,050,000-token context window, and 128K max output. Key datapack rows: Terminal-Bench 2.1 78.2%, SWE-bench Pro 58.6%, GPQA Diamond 93.6%, ARC-AGI-2 high effort 83.3%, BrowseComp Pro compute 90.1%, and FrontierMath Tier 4 39.6%. Official pricing is $30/M input, $180/M output, $10/M batch input, and $45/M batch output; native cached input discount is not listed.
1.05m
Context
- #6GPT-5.4
GPT-5.4 is OpenAI's flagship frontier reasoning model, released March 5, 2026. It incorporates advances from GPT-5.3-Codex for coding and agentic workflows, and adds 'Thinking' mode with editable reasoning plans. Key capabilities include computer use (navigating interfaces via Playwright), image understanding and generation integration, full-stack web app generation, tool calling, and deep research. Knowledge cutoff is August 31, 2025. Model ID: gpt-5.4.
1.05m
Context
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