Best LLM for long-document q&a
Single huge document (legal, financial, research) + question → answer.
Why this ranking is opinionated
Distinct from RAG: no retrieval, the whole doc goes in context. Mandates very large context windows and good needle-in-haystack performance. Input pricing dominates total cost.
Top 5 recommendations
ranked by monthly cost at this workload- · Cheapest qualifying option at this workload (~$0.00/mo).
- · ~$0.00/mo (+0% over the cheapest option).
- · 1,048,576 tokens of context — far above this use case's 200,000-token minimum.
- · ~$0.00/mo (+0% over the cheapest option).
- · ~$0.00/mo (+0% over the cheapest option).
- · ~$0.00/mo (+0% over the cheapest option).
- · 1,048,576 tokens of context — far above this use case's 200,000-token minimum.
Frequently asked questions
What makes a good LLM for long-document q&a?
Distinct from RAG: no retrieval, the whole doc goes in context. Mandates very large context windows and good needle-in-haystack performance. Input pricing dominates total cost.
What capabilities matter most for long-document q&a?
For long-document q&a the typical filters are: no specific capability requirement, and a context window of at least 200k tokens. The ranking on this page weights monthly cost (at the workload defaults shown above) most heavily, then capability fit.
What is currently the cheapest LLM for long-document q&a?
At the typical workload defaults, Trinity Large Thinking (free) from Arcee AI ranks cheapest right now (~$0 / month). Plug your own monthly token volumes into the calculator on this page for a workload-specific number.
Is the cheapest LLM always the right choice for long-document q&a?
Not always. Cheap models often trade off reasoning quality, tool reliability, or context size. Use the cheapest as a baseline and benchmark against a tier-up model on your own evaluation set before committing to a contract — quality differences compound over millions of tokens.