Particle-1 (Reasoning)
by Particle AI
Particle-1 (Reasoning) is a reasoning model from Particle AI, released on October 28, 2026. It has a 1M-token context window and can generate up to 131K output tokens. API pricing is $0.25 per 1M input tokens and $1 per 1M output tokens. It ranks #90 of 247 models by Intelligence Score with a score of 32.
Particle-1 is Particle AI's first model, a reinforcement-learning post-train of DeepSeek V4.1 Flash (rank-64 LoRA over the experts in all layers, trained with GSPO in Cascade RL stages on internal coding and data-engineering environments). It targets agentic software engineering and is tuned to solve tasks with fewer tokens: Particle reports 28.4% to 52.2% fewer output tokens and 34.4% to 51.6% lower cost per task than the base model on Terminal-Bench 2.1, ReactBench, ADE Bench, and DeepSWE 1.1, with pass@1 within the base model's confidence intervals (72.57% aggregate task pass rate vs 71.15% for DeepSeek V4.1 Flash). Text and image input, text output, reasoning with effort control, OpenAI-compatible tool calling, 1,048,576-token context and 131,072 max output tokens. Weights are not released; it is available through the Particle API and OpenRouter (particle-ai/particle-1) at $0.25 input, $0.03 cached input, and $1.00 output per million tokens (peak; off-peak 50% off, 20:30 to 04:00 America/New_York).
Key specs
| Provider | Particle AI |
|---|---|
| Release date | 2026-10-28 |
| License | proprietary |
| Context window | 1M tokens |
| Max output | 131K tokens |
| Input price | $0.25 / 1M tokens |
| Output price | $1 / 1M tokens |
| Intelligence Score | 32 |
Quick answers
What is the context window of Particle-1 (Reasoning)?
Particle-1 (Reasoning) has a context window of 1M tokens, with a maximum output of 131K tokens per response.
How much does Particle-1 (Reasoning) cost?
Particle-1 (Reasoning) costs $0.25 per 1M input tokens and $1 per 1M output tokens through the API.
Is Particle-1 (Reasoning) open source?
No. Particle-1 (Reasoning) is a proprietary model from Particle AI (proprietary license).
When was Particle-1 (Reasoning) released?
Particle AI released Particle-1 (Reasoning) on October 28, 2026.
How does Particle-1 (Reasoning) compare to Claude Opus 5.5 (Reasoning)?
Particle-1 (Reasoning) scores 32 on the Intelligence Score versus 59.9 for Claude Opus 5.5 (Reasoning), the current #1. Input pricing is $0.25 vs $4 per 1M tokens.