Grok 4 Fast vs o4-mini
Grok 4 Fast and o4-mini are closely matched at 31.7 and 27.5 on the LLM Stats Score. Grok 4 Fast is 7.0x cheaper per token.
xAI · OpenAI · Updated for 2026
Which is better?
Grok 4 Fast and o4-mini are closely matched on the overall LLM Stats Score at 31.7 and 27.5.
The models split the 4 individual benchmarks reported for both models evenly.
On price, Grok 4 Fast is roughly 7.0x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
Grok 4 Fast also accepts a larger context window (2,000,000 input tokens), making it the stronger choice for long documents and large codebases.
Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.
Choose Grok 4 Fast
- cost matters — it's about 7.0x cheaper per token
- you process long inputs — it offers a 2,000,000 token context window
- you want the most recent training data — it shipped Aug 2025
Choose o4-mini
- you want predictable pricing at $1.10/M input and $4.40/M output
At a glance
The differences that matter most.
Capability indexes
Additional strengths measured across groups of related public benchmarks
Individual benchmarks
7 reported for Grok 4 Fast · 14 for o4-mini
Grok 4 Fast outperforms in 2 benchmarks (GPQA, Humanity's Last Exam), while o4-mini is better at 2 benchmarks (AIME 2025, BrowseComp).
Both models are evenly matched across the benchmarks.
Human preference
Blind head-to-head votes and playground preference scores
Pricing Analysis
Price comparison per million tokens
For input processing, Grok 4 Fast ($0.20/1M tokens) is 5.5x cheaper than o4-mini ($1.10/1M tokens).
For output processing, Grok 4 Fast ($0.50/1M tokens) is 8.8x cheaper than o4-mini ($4.40/1M tokens).
In conclusion, o4-mini is more expensive than Grok 4 Fast.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
Grok 4 Fast accepts 2,000,000 input tokens compared to o4-mini's 200,000 tokens. o4-mini can generate longer responses up to 100,000 tokens, while Grok 4 Fast is limited to 30,000 tokens.
Input capabilities
Documented input modalities across available providers
Both Grok 4 Fast and o4-mini support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
Grok 4 Fast
o4-mini
License
Usage and distribution terms
Both models are licensed under proprietary licenses.
Both models have usage restrictions defined by their respective organizations.
Proprietary
Closed source
Proprietary
Closed source
Release Timeline
When each model was launched
Grok 4 Fast was released on 2025-08-28, while o4-mini was released on 2025-04-16.
Grok 4 Fast is 4 months newer than o4-mini.
Aug 28, 2025
1.1 years ago
4mo newerApr 16, 2025
1.4 years ago
Knowledge Cutoff
When training data ends
o4-mini has a documented knowledge cutoff of 2024-05-31, while Grok 4 Fast's cutoff date is not specified.
We can confirm o4-mini's training data extends to 2024-05-31, but cannot make a direct comparison without Grok 4 Fast's cutoff date.
—
May 2024
Provider Availability
Grok 4 Fast is available from xAI. o4-mini is available from OpenAI.
Grok 4 Fast
o4-mini
Outputs Comparison
Judge for yourself.
Run your own prompts against Grok 4 Fast and o4-mini side-by-side, then vote on the output you prefer.
FAQ
Common questions about Grok 4 Fast vs o4-mini.