What is the difference between Llama 3.1 405B and Mercury 2.5 Preview?

Llama 3.1 405B is developed by Meta AI while Mercury 2.5 Preview is developed by Inception. Llama 3.1 405B has a 128K token context window vs Mercury 2.5 Preview's 260K. You can compare their actual outputs across 12 challenges on Rival to see how they differ in practice.

Which is better, Llama 3.1 405B or Mercury 2.5 Preview?

It depends on your use case. Llama 3.1 405B and Mercury 2.5 Preview each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 12 challenges so you can judge which fits your needs best.

How much does Llama 3.1 405B cost compared to Mercury 2.5 Preview?

Llama 3.1 405B costs $2.7/M input tokens and Mercury 2.5 Preview costs $0.04/M input tokens. Mercury 2.5 Preview is $2.66/M cheaper per input. Check their side-by-side outputs on Rival to see if the price difference is justified by quality.

How can I compare Llama 3.1 405B and Mercury 2.5 Preview on Rival?

This page shows a side-by-side comparison of Llama 3.1 405B and Mercury 2.5 Preview across shared challenges. You can vote on which model produced the better output in a blind duel. Browsing and voting are free. No account is needed to look; signing in only saves your votes and likes.

Updated Aug 2026

Llama 3.1 405BvsMercury 2.5 Preview

Mercury 2.5 Preview is cheaper than Llama 3.1 405B at $0.04/M vs $2.7/M input tokens.

Llama 3.1 405B and Mercury 2.5 Preview compared across 12 shared prompts
Spec	Llama 3.1 405B	Mercury 2.5 Preview
Input price	$2.7/M tokens	$0.04/M tokens
Output price	$3.1/M tokens	$0.15/M tokens
Context window	128K tokens	260K tokens
Weights	Open	—
Free API (OpenRouter)	No	No
Released	Jul 2024	Aug 2026