GPT-5 nano vs Grok-4 Heavy
Grok-4 Heavy significantly outperforms across most benchmarks.
OpenAI · xAI · Updated for 2026
Which is better?
GPT-5 nano outperforms in 0 benchmarks, while Grok-4 Heavy is better at 3 benchmarks (AIME 2025, GPQA, Humanity's Last Exam). Grok-4 Heavy significantly outperforms across most benchmarks.
Based on current benchmark, pricing, and model metadata for 2026.
Choose GPT-5 nano
- you want predictable pricing at $0.05/M input and $0.40/M output
Choose Grok-4 Heavy
- you want the strongest raw capability — it leads on 3 of 3 shared benchmarks
At a glance
The differences that matter most.
Performance Benchmarks
Comparative analysis across standard metrics
GPT-5 nano outperforms in 0 benchmarks, while Grok-4 Heavy is better at 3 benchmarks (AIME 2025, GPQA, Humanity's Last Exam).
Grok-4 Heavy significantly outperforms across most benchmarks.
Arena Performance
Playground indexes and blind preference scores
Context Window
Maximum input and output token capacity
Only GPT-5 nano specifies input context (400,000 tokens). Only GPT-5 nano specifies output context (128,000 tokens).
Input Capabilities
Supported data types and modalities
Both GPT-5 nano and Grok-4 Heavy support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
GPT-5 nano
Grok-4 Heavy
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
GPT-5 nano was released on 2025-08-07, while Grok-4 Heavy's release date is not specified.
We can confirm GPT-5 nano's release timeline, but cannot make a direct age comparison without Grok-4 Heavy's release date.
Aug 7, 2025
1.0 years ago
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Knowledge Cutoff
When training data ends
GPT-5 nano has a knowledge cutoff of 2024-05-30, while Grok-4 Heavy has a cutoff of 2024-12-31.
Grok-4 Heavy has more recent training data (up to 2024-12-31), making it potentially better informed about events through that date compared to GPT-5 nano (2024-05-30).
May 2024
Dec 2024
7 mo newerOutputs Comparison
Judge for yourself.
Run your own prompts against GPT-5 nano and Grok-4 Heavy side-by-side, then vote on the output you prefer.
FAQ
Common questions about GPT-5 nano vs Grok-4 Heavy.