# OpenAI vs Cerebras

> Partners as much as rivals: OpenAI rents Cerebras capacity and previewed an Ultrafast GPT-5.6 Sol on it. Cerebras sells raw speed on open models; OpenAI sells the closed frontier.

Canonical: https://www.subconscious.dev/compare/openai-vs-cerebras · By The Subconscious Team · Updated September 30, 2026

## How they compare

These two are tied together. A January 2026 deal worth over $10B has OpenAI renting roughly 750 MW of Cerebras capacity through 2028, and on August 13, 2026 OpenAI previewed an Ultrafast tier of GPT-5.6 Sol running on Cerebras at up to 750 output tokens per second. That preview is the only wafer-scale path to a closed frontier model. Otherwise, the Cerebras public shared catalog is thin: GPT-OSS 120B, near 3,000 tokens per second at $0.35 in and $0.75 out, and Gemma 4 31B. Other model families sit on dedicated endpoints and partner platforms.

For most workloads, the real question is whether generation speed is the bottleneck. Cerebras shines on voice, live code autocomplete and streaming UIs where the user waits on output. It helps less when an agent mostly waits on tools or hidden reasoning, and most models beyond the shared two mean a sales conversation. OpenAI offers the full range from Astra to Luna, a 1.05M window, hosted tools and Fast mode at up to 2.5x for double the price. Teams that want GPT quality at extreme speed can watch the Ultrafast Sol preview.

## What each one does

### OpenAI

OpenAI runs the most widely adopted closed-model API. Its September 2026 lineup has GPT-6 Astra at the top for computer use, coding and long agentic runs, priced at $10 in and $50 out per million tokens. Below it sits the GPT-5.6 family: Sol for hard professional work, Terra as the balanced default, and Luna for high-volume jobs at $0.20 in and $1.20 out. All of them carry a 1.05M token context window with up to 128K output.

### Cerebras

Cerebras builds a single chip the size of a silicon wafer, and its inference cloud is the fastest public host on the models it serves. Its developer table lists GPT-OSS 120B near 3,000 tokens per second, about six times Groq on the same weights, at $0.35 in and $0.75 out per million. The public shared catalog is thin, just GPT-OSS 120B and Gemma 4 31B as of August 2026. More model families live on dedicated endpoints and through partners like OpenRouter, Hugging Face, Vercel and AWS Marketplace.

## Which is best, and when

### Choose OpenAI for

- Access to closed GPT tiers, including the Ultrafast Sol preview
- Agents that spend most of their time on tools and reasoning
- Long-context work up to 1.05M tokens

### Choose Cerebras for

- Streaming UIs and live autocomplete where output speed is the wait
- The fastest published throughput on GPT-OSS 120B
- Agent steps that emit long outputs on open weights

## At a glance

| Attribute | OpenAI | Cerebras |
|---|---|---|
| Model access | Closed, plus open gpt-oss | Open weights |
| Flagship models | GPT-6 Astra, GPT-5.6 Sol, Terra, Luna | GPT-OSS 120B, Gemma 4 31B |
| Speed | Fast mode: up to 2.5x at 2x price | ~3,000 tok/s on GPT-OSS 120B |
| Price | $0.20–$10 in, $1.20–$50 out per 1M | $0.35 in, $0.75 out (GPT-OSS 120B) |
| Customization | N/A | - |
| Deployment | API, Azure OpenAI, Bedrock | Shared API, dedicated, partners |
| Long context | 1.05M; 2x input past 272K | - |

## FAQ

### What is the difference between OpenAI and Cerebras?

Partners as much as rivals: OpenAI rents Cerebras capacity and previewed an Ultrafast GPT-5.6 Sol on it. Cerebras sells raw speed on open models; OpenAI sells the closed frontier.

### When should I choose OpenAI over Cerebras?

Access to closed GPT tiers, including the Ultrafast Sol preview; Agents that spend most of their time on tools and reasoning; Long-context work up to 1.05M tokens.

### When should I choose Cerebras over OpenAI?

Streaming UIs and live autocomplete where output speed is the wait; The fastest published throughput on GPT-OSS 120B; Agent steps that emit long outputs on open weights.

### Is OpenAI or Cerebras cheaper?

OpenAI: $0.20–$10 in, $1.20–$50 out per 1M. Cerebras: $0.35 in, $0.75 out (GPT-OSS 120B). The cheaper choice depends on the model and workload.

## Running long-horizon agents?

If your agents run past 200K tokens, compare both against Subconscious: [Subconscious vs OpenAI](https://www.subconscious.dev/compare/subconscious-vs-openai.md), [Subconscious vs Cerebras](https://www.subconscious.dev/compare/subconscious-vs-cerebras.md).

Full profiles: [OpenAI](https://www.subconscious.dev/providers/openai.md), [Cerebras](https://www.subconscious.dev/providers/cerebras.md).