Language Models
X

Inception's Mercury 2.5, a diffusion model at $0.75 per million output tokens

2026/09/15

Inception released Mercury 2.5 on 9 September 2026⁠[1]. It calls it the most capable diffusion language model on the market and, to its knowledge, the largest one ever trained⁠[1].

Most language models write left to right, one token at a time. A diffusion model produces many tokens together and refines them over several passes.

The context window is 260K tokens⁠[1]. Inception puts its speed at 1,107 tokens per second on widely available NVIDIA GPUs⁠[1].

The standard price is $0.20 per million input tokens and $0.75 per million output tokens⁠[1]. At launch it is 80 percent off, at $0.04 and $0.15, and the announcement gives no end date for the discount⁠[1].

Inception describes its quality as comparable to cost-optimized frontier models such as GPT-5.6 Luna (Low), Gemini 3.5 Flash-Lite and Claude Haiku 4.5⁠[1]. It does not say what the comparison is based on⁠[1].

For reference, gpt-5.6-luna is $0.20 input and $1.20 output, and Claude Haiku 4.5 is $1 and $5⁠[2,3]. At the standard price Mercury 2.5 matches luna on input and costs nearly 40 percent less on output.

It supports tunable reasoning, parallel tool calls and schema-aligned JSON⁠[1]. It is available through Inception's own API, Baseten and OpenRouter⁠[1].