GPT-5.1-Codex-Max vs Grok 4.20
| Signal | GPT-5.1-Codex-Max | Delta | Grok 4.20 |
|---|---|---|---|
Capabilities | 100 | -- | |
Benchmarks | 88 | +2 | |
Pricing | 90 | -7 | |
Context window size | 80 | -10 | |
Recency | 93 | -7 | |
Output Capacity | 85 | +65 | |
| Overall Result | 2 wins | of 6 | 3 wins |
Score History
88.2
current score
Grok 4.20
right now
88.3
current score
GPT-5.1-Codex-Max
OpenAI
Grok 4.20
xAI
Grok 4.20 saves you $375.00/month
That's $4500.00/year compared to GPT-5.1-Codex-Max at your current usage level of 100K calls/month.
| Metric | GPT-5.1-Codex-Max | Grok 4.20 | Winner |
|---|---|---|---|
| Overall Score | 88 | 88 | Grok 4.20 |
| Rank | #28 | #27 | Grok 4.20 |
| Quality Rank | #28 | #27 | Grok 4.20 |
| Adoption Rank | #28 | #27 | Grok 4.20 |
| Parameters | -- | -- | -- |
| Context Window | 400K | 2000K | Grok 4.20 |
| Pricing | $1.25/$10.00/M | $1.25/$2.50/M | -- |
| Signal Scores | |||
| Capabilities | 100 | 100 | GPT-5.1-Codex-Max |
| Benchmarks | 88 | 86 | GPT-5.1-Codex-Max |
| Pricing | 90 | 98 | Grok 4.20 |
| Context window size | 80 | 90 | Grok 4.20 |
| Recency | 93 | 100 | Grok 4.20 |
| Output Capacity | 85 | 20 | GPT-5.1-Codex-Max |
Our score (0-100) is driven by benchmark performance (90%) from Arena Elo ratings, MMLU, GPQA, HumanEval, SWE-bench, and 15+ standardized evaluations. Capabilities and context window serve as tiebreakers (10%). Learn more about our methodology.
Scores 88/100 (rank #28), placing it in the top 91% of all 290 models tracked.
Scores 88/100 (rank #27), placing it in the top 91% of all 290 models tracked.
With only a 0-point gap, these models are in the same performance tier. The practical difference in output quality is minimal - your choice should depend on pricing, latency requirements, and specific feature needs.
Choose GPT-5.1-Codex-Max when you need:
- Step-by-step reasoning and chain-of-thought problem solving
Choose Grok 4.20 when you need:
- High-volume production workloads where API costs must be minimized
- Processing long documents or large codebases (2000K token context)
- Step-by-step reasoning and chain-of-thought problem solving
Grok 4.20 offers 67% better value per quality point. At 1M tokens/day, you'd spend $56.25/month with Grok 4.20 vs $168.75/month with GPT-5.1-Codex-Max - a $112.50 monthly difference.
Both models have comparable response speeds. For most applications, the latency difference is negligible.
When latency matters most: Interactive chatbots, IDE code completion, real-time translation, and user-facing applications where response time directly impacts experience. For batch processing, background summarization, or offline analysis, latency is less critical.
Code generation & review
Based on overall model capabilities and architecture for coding tasks like generating functions, debugging, and refactoring
Customer support chatbot
Suitable for user-facing chat with competitive response times. Grok 4.20 also offers lower per-token costs for high-volume support
Long document analysis
Larger context window (2000K tokens) can process longer documents, contracts, and research papers in a single pass
Batch data extraction
Lower output pricing ($2.50/M) reduces costs when processing thousands of records daily
Creative writing & content
Higher overall composite score (88/100) correlates with better nuance, coherence, and style in long-form content
Image understanding & OCR
Supports vision input - can analyze screenshots, diagrams, photos, and scanned documents directly
GPT-5.1-Codex-Max and Grok 4.20 are extremely close in overall performance (only 0.09999999999999432 points apart). Your best choice depends entirely on which specific strengths matter most for your use case.
By Use Case
Best for Quality
GPT-5.1-Codex-Max
Marginally better benchmark scores; both are excellent
Best for Cost
Grok 4.20
67% lower pricing; better value at scale
Best for Reliability
GPT-5.1-Codex-Max
Higher uptime and faster response speeds
Best for Prototyping
GPT-5.1-Codex-Max
Stronger community support and better developer experience
Best for Production
GPT-5.1-Codex-Max
Wider enterprise adoption and proven at scale
by OpenAI
- Choose for Quality - Marginally better benchmark scores; both are excellent
- Choose for Reliability - Higher uptime and faster response speeds
- Choose for Prototyping - Stronger community support and better developer experience
- Choose for Production - Wider enterprise adoption and proven at scale
| Capability | GPT-5.1-Codex-Max | Grok 4.20 |
|---|---|---|
| Vision (Image Input) | ||
| Function Calling | ||
| Streaming | ||
| JSON Mode | ||
| Reasoning | ||
| Web Search | ||
| Image Output |
GPT-5.1-Codex-Max
OpenAI
Grok 4.20
xAI
Grok 4.20 saves you $9.00/month
That's 63% cheaper than GPT-5.1-Codex-Max at 1,000 tokens/request and 100 requests/day.
Assumes 60% input / 40% output token ratio per request. Actual costs may vary based on your usage pattern.
| Parameter | GPT-5.1-Codex-Max | Grok 4.20 |
|---|---|---|
| Context Window | 400K | 2M |
| Max Output Tokens | 128,000 | -- |
| Open Source | No | No |
| Created | Dec 4, 2025 | Mar 31, 2026 |
Grok 4.20's performance edge likely stems from its massive 2M token context window - 5x larger than GPT-5.1-Codex-Max's 400K - which is crucial for handling large codebases and multi-file projects. The $4/M output token savings with GPT-5.1-Codex-Max ($6/M vs $10/M) becomes less relevant when Grok can process entire repositories in a single pass, reducing the need for multiple API calls and context management overhead.
Raw benchmark performance drives the ranking disparity - Grok 4.20 sits at #3 with a 74/100 score while GPT-5.1-Codex-Max languishes at #15 with 61/100, suggesting xAI's model excels at the specific coding tasks measured. The 5x context window advantage (2M vs 400K tokens) particularly shines in real-world coding scenarios where understanding entire project structures matters more than theoretical capability checkboxes.
GPT-5.1-Codex-Max's explicit 128K output guarantee at $10/M tokens suits code generation tasks requiring massive outputs like full application scaffolding or documentation generation. However, with Grok's 60% cheaper output pricing ($6/M) and superior 74/100 performance score, you'd need to consistently generate over 80K tokens per request to offset the quality gap - a rare scenario outside of specialized bulk generation workflows.
For a typical 50K-token codebase review generating 10K tokens of suggestions, Grok 4.20 costs $0.16 total ($0.10 input + $0.06 output) versus GPT-5.1-Codex-Max's $0.16 ($0.06 input + $0.10 output) - essentially identical despite the input price difference. The real differentiator becomes Grok's ability to handle 2M tokens in one shot versus requiring 5 separate API calls with GPT-5.1-Codex-Max's 400K limit, which multiplies both cost and complexity.
Migration makes sense for performance-critical applications - Grok's #3 ranking versus #15 represents a substantial quality jump at only 60% higher input costs ($2/M vs $1.25/M) while actually saving 40% on outputs. However, teams deeply integrated with OpenAI's tooling, fine-tuning infrastructure, or requiring the explicit 128K output guarantee should factor in migration complexity against the 13-point score improvement.