Grok Code Fast 1 vs o3
Grok Code Fast 1 (2025) and o3 (2025) are agentic coding models from xAI and OpenAI. Grok Code Fast 1 ships a 262K-token context window, while o3 ships a 200K-token context window. On SWE-bench Verified, o3 leads by a hair. On pricing, Grok Code Fast 1 costs $0.2/1M input tokens versus $2/1M for the alternative. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit.
Grok Code Fast 1 is ~900% cheaper at $0.2/1M; pay for o3 only for coding workflow support.
Specs
| Specification | ||
|---|---|---|
| Released | 2025-08-27 | 2025-03-31 |
| Context window | 262K | 200K |
| Parameters | 314B | — |
| Architecture | mixture of experts | decoder only |
| License | Proprietary | Proprietary |
| Knowledge cutoff | - | - |
Pricing and availability
| Pricing attribute | Grok Code Fast 1 | o3 |
|---|---|---|
| Input price | $0.2/1M tokens | $2/1M tokens |
| Output price | $1.5/1M tokens | $8/1M tokens |
| Providers |
Capabilities
| Capability | Grok Code Fast 1 | o3 |
|---|---|---|
| Vision | No | No |
| Multimodal | No | No |
| Reasoning | No | Yes |
| Function calling | Yes | No |
| Tool use | Yes | No |
| Structured outputs | Yes | Yes |
| Code execution | No | Yes |
Benchmarks
| Benchmark | Grok Code Fast 1 | o3 |
|---|---|---|
| SWE-bench Verified | 70.8 | 71.7 |
Deep dive
On shared benchmark coverage, SWE-bench Verified has Grok Code Fast 1 at 70.8 and o3 at 71.7, with o3 ahead by 0.9 points. The largest visible gap is 0.9 points on SWE-bench Verified, which matters most when that benchmark mirrors your workload. Treat isolated benchmark wins as directional, because provider routing, prompt style, and tool access can move real application results.
The capability footprint differs most on reasoning mode: o3, function calling: Grok Code Fast 1, tool use: Grok Code Fast 1, and code execution: o3. Both models share structured outputs, so the practical split is not just feature count. Use those differences to decide whether the page is about raw model quality, agentic coding support, multimodal ingestion, or predictable structured API behavior.
For cost, Grok Code Fast 1 lists $0.2/1M input and $1.5/1M output tokens, while o3 lists $2/1M input and $8/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts Grok Code Fast 1 lower by about $3.21 per million blended tokens. Availability is 1 providers versus 2, so concentration risk also matters.
Choose Grok Code Fast 1 when coding workflow support, larger context windows, and lower input-token cost are central to the workload. Choose o3 when coding workflow support and broader provider choice are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship.
FAQ
Which has a larger context window, Grok Code Fast 1 or o3?
Grok Code Fast 1 supports 262K tokens, while o3 supports 200K tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Which is cheaper, Grok Code Fast 1 or o3?
Grok Code Fast 1 is cheaper on tracked token pricing. Grok Code Fast 1 costs $0.2/1M input and $1.5/1M output tokens. o3 costs $2/1M input and $8/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is Grok Code Fast 1 or o3 open source?
Grok Code Fast 1 is listed under Proprietary. o3 is listed under Proprietary. License labels affect whether you can self-host, redistribute weights, or rely only on hosted APIs, so confirm the upstream license before deployment.
Which is better for reasoning mode, Grok Code Fast 1 or o3?
o3 has the clearer documented reasoning mode signal in this comparison. If reasoning mode is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Which is better for function calling, Grok Code Fast 1 or o3?
Grok Code Fast 1 has the clearer documented function calling signal in this comparison. If function calling is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Where can I run Grok Code Fast 1 and o3?
Grok Code Fast 1 is available on OpenRouter. o3 is available on OpenAI API and OpenRouter. Provider coverage can affect latency, region availability, compliance posture, and fallback options. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
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Last reviewed: 2026-05-11. Data sourced from public model cards and provider documentation.