GPT-5.1 Instant vs Grok-4 Heavy
GPT-5.1 Instant and Grok-4 Heavy are closely matched at 36.7 and 40.6 on the LLM Stats Score.
OpenAI · xAI · Updated for 2026
Which is better?
GPT-5.1 Instant and Grok-4 Heavy are closely matched on the overall LLM Stats Score at 36.7 and 40.6.
In the 2 individual benchmarks reported for both models, Grok-4 Heavy wins 2; this is a narrower head-to-head signal than the composite indexes.
Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.
Choose GPT-5.1 Instant
- you want predictable pricing at $1.25/M input and $10.00/M output
Choose Grok-4 Heavy
- you value its reported benchmark strengths — it wins 2 of 2 exact shared results
At a glance
The differences that matter most.
Capability indexes
Additional strengths measured across groups of related public benchmarks
Individual benchmarks
9 reported for GPT-5.1 Instant · 6 for Grok-4 Heavy
GPT-5.1 Instant outperforms in 0 benchmarks, while Grok-4 Heavy is better at 2 benchmarks (AIME 2025, GPQA).
Grok-4 Heavy significantly outperforms across most benchmarks.
Human preference
Blind head-to-head votes and playground preference scores
Context Window
Maximum input and output token capacity
Only GPT-5.1 Instant specifies input context (400,000 tokens). Only GPT-5.1 Instant specifies output context (128,000 tokens).
Input capabilities
Documented input modalities across available providers
Both GPT-5.1 Instant and Grok-4 Heavy support multimodal inputs.
They are both capable of processing various types of data, offering versatility in application.
GPT-5.1 Instant
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-5.1 Instant was released on 2025-11-12, while Grok-4 Heavy's release date is not specified.
We can confirm GPT-5.1 Instant's release timeline, but cannot make a direct age comparison without Grok-4 Heavy's release date.
Nov 12, 2025
11 months ago
—
Knowledge Cutoff
When training data ends
Grok-4 Heavy has a documented knowledge cutoff of 2024-12-31, while GPT-5.1 Instant's cutoff date is not specified.
We can confirm Grok-4 Heavy's training data extends to 2024-12-31, but cannot make a direct comparison without GPT-5.1 Instant's cutoff date.
—
Dec 2024
Outputs Comparison
Judge for yourself.
Run your own prompts against GPT-5.1 Instant and Grok-4 Heavy side-by-side, then vote on the output you prefer.
FAQ
Common questions about GPT-5.1 Instant vs Grok-4 Heavy.