Grok 4.1 Fast vs OpenAI o3
Benchmarks, API pricing and specs, head to head. Data updated 2026-06-10.
Grok 4.1 Fast
xAI · Nov 2025
A 2M-token context window for $0.20 per million input tokens — the cheapest long-context frontier offering anywhere.
OpenAI o3
68.9OpenAI · Apr 2025
OpenAI's dedicated 2025 reasoning model that pioneered thinking-with-images and agentic tool use within chain-of-thought.
The verdict
These two models don't yet share verified results on the benchmarks we track, so judge them on specs, pricing and intended use. On price the gap is dramatic: Grok 4.1 Fast works out roughly 13x cheaper per blended million tokens. Grok 4.1 Fast also takes 2M of context versus 200K for OpenAI o3.
Specs & pricing
| Grok 4.1 Fast | OpenAI o3 | |
|---|---|---|
| modhub Index | — | 68.9 |
| Input price / 1M | $0.2 | $2 |
| Output price / 1M | $0.5 | $8 |
| Context window | 2M | 200K |
| Max output | — | 100K |
| Open weights | no | no |
| Reasoning model | yes | yes |
| Multimodal input | text, image | text, image |
| Knowledge cutoff | Nov 2025 | May 2024 |
| Released | Nov 2025 | Apr 2025 |
| Example monthly cost* | $2.75 | $32.00 |
* 10M input + 1.5M output tokens per month at list prices, no caching. Green = better value on that row.
Frequently asked questions
- Which is better, Grok 4.1 Fast or OpenAI o3?
- These two models don't yet share verified results on the benchmarks we track, so judge them on specs, pricing and intended use. On price the gap is dramatic: Grok 4.1 Fast works out roughly 13x cheaper per blended million tokens. Grok 4.1 Fast also takes 2M of context versus 200K for OpenAI o3.
- Which is cheaper, Grok 4.1 Fast or OpenAI o3?
- Grok 4.1 Fast costs $0.2/$0.5 per million input/output tokens, while OpenAI o3 costs $2/$8. For a typical workload of 10M input and 1.5M output tokens per month, that's $2.75 versus $32.00.
- Which model is better for coding, Grok 4.1 Fast or OpenAI o3?
- We don't yet track SWE-bench Verified results for both models; check their individual pages for coding-related scores.