Everything about Mercury 3

Mercury 3 at a glance

Inception released Mercury 3 on October 16, 2026. It has a reasoning mode: it can "think" before answering, which helps with multi-step problems but uses more tokens, and therefore more money. It is a closed model: you access it through an API, from Inception or one of the 3 providers listed on models.dev. It is a very recent release.

We file it under budget models (24 models in this category on the site).

Measured performance

As of October 22, 2026, Epoch AI publishes no score for Mercury 3 on our basket's benchmarks. To place it, rely on its specifications and price, then test it on your own cases.

Context and capabilities

Its context window reaches 1,000,000 tokens, roughly 1,500 pages of text at 500 words per page: enough to load a whole book or a mid-sized codebase. A single answer can run to 131,072 tokens.

It accepts as input: text.

It can call tools (functions, APIs) and return structured JSON output, which makes it a possible foundation for an AI agent.

How much does Mercury 3 cost?

Mercury 3 costs $0.10 per million input tokens and $0.35 per million output tokens (developer's price, checked on October 22, 2026).

To put it in perspective: reading 20,000 tokens (about thirty pages) and writing 2,000 costs roughly $0.003; a thousand of those tasks, $2.7.

That is 3.2 times cheaper than the median output price of budget models ($1.13).

Tokens read back from cache cost $0.01 per million, which helps an agent that keeps resending the same context.

To estimate your own budget, use the agent cost calculator.

Who is it for?

Given its category, Mercury 3 is mainly aimed at high volumes where every cent counts: sorting, information extraction, summaries, simple assistants.

Its very large context window makes it worth considering for analysing large sets of documents in a single request.

Its very low cost (under half a cent for our sample task) means it can be called thousands of times a day.

Before adopting it, test it on your own examples: benchmarks measure standard tasks, not your job.

Alternatives

In the same category, the models closest to Mercury 3 are:

• Qwen3.5 Flash (Alibaba Cloud (Qwen), index 62.6)
• Solar Mini 4 (Upstage, $0.40 per million output tokens)
• Seed 2.0 Mini (ByteDance Seed, $0.40 per million output tokens)
• GPT-6 Luna (OpenAI, index 80.3)