GPT-5.6 Luna vs Grok 4.20
| Signal | GPT-5.6 Luna | Delta | Grok 4.20 |
|---|---|---|---|
Capabilities | 100 | -- | |
Benchmarks | 88 | +1 | |
Pricing | 97 | 0 | |
Context window size | 96 | -4 | |
Recency | 100 | -- | |
Output Capacity | 85 | +65 | |
| Overall Result | 2 wins | of 6 | 2 wins |
Score History
89
current score
GPT-5.6 Luna
right now
88.8
current score
GPT-5.6 Luna
OpenAI
Grok 4.20
xAI
GPT-5.6 Luna saves you $50.00/month
That's $600.00/year compared to Grok 4.20 at your current usage level of 100K calls/month.
| Metric | GPT-5.6 Luna | Grok 4.20 | Winner |
|---|---|---|---|
| Overall Score | 89 | 89 | GPT-5.6 Luna |
| Rank | #22 | #29 | GPT-5.6 Luna |
| Quality Rank | #22 | #29 | GPT-5.6 Luna |
| Adoption Rank | #22 | #29 | GPT-5.6 Luna |
| Parameters | -- | -- | -- |
| Context Window | 1050K | 2000K | Grok 4.20 |
| Pricing | $0.50/$3.00/M | $1.25/$2.50/M | -- |
| Signal Scores | |||
| Capabilities | 100 | 100 | GPT-5.6 Luna |
| Benchmarks | 88 | 86 | GPT-5.6 Luna |
| Pricing | 97 | 98 | Grok 4.20 |
| Context window size | 96 | 100 | Grok 4.20 |
| Recency | 100 | 100 | GPT-5.6 Luna |
| Output Capacity | 85 | 20 | GPT-5.6 Luna |
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 89/100 (rank #22), placing it in the top 93% of all 290 models tracked.
Scores 89/100 (rank #29), placing it in the top 90% 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-5.6 Luna when you need:
- Step-by-step reasoning and chain-of-thought problem solving
Choose Grok 4.20 when you need:
- Processing long documents or large codebases (2000K token context)
- Step-by-step reasoning and chain-of-thought problem solving
GPT-5.6 Luna offers 7% better value per quality point. At 1M tokens/day, you'd spend $52.50/month with GPT-5.6 Luna vs $56.25/month with Grok 4.20 - a $3.75 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 (89/100) 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-5.6 Luna and Grok 4.20 are extremely close in overall performance (only 0.20000000000000284 points apart). Your best choice depends entirely on which specific strengths matter most for your use case.
By Use Case
Best for Quality
GPT-5.6 Luna
Marginally better benchmark scores; both are excellent
Best for Cost
GPT-5.6 Luna
7% lower pricing; better value at scale
Best for Reliability
GPT-5.6 Luna
Higher uptime and faster response speeds
Best for Prototyping
GPT-5.6 Luna
Stronger community support and better developer experience
Best for Production
GPT-5.6 Luna
Wider enterprise adoption and proven at scale
by OpenAI
- Choose for Quality - Marginally better benchmark scores; both are excellent
- Choose for Cost - 7% lower pricing; better value at scale
- 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-5.6 Luna | Grok 4.20 |
|---|---|---|
| Vision (Image Input) | ||
| Function Calling | ||
| Streaming | ||
| JSON Mode | ||
| Reasoning | ||
| Web Search | ||
| Image Output |
GPT-5.6 Luna
OpenAI
Grok 4.20
xAI
GPT-5.6 Luna saves you $0.7500/month
That's 14% cheaper than Grok 4.20 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-5.6 Luna | Grok 4.20 |
|---|---|---|
| Context Window | 1.1M | 2M |
| Max Output Tokens | 128,000 | -- |
| Open Source | No | No |
| Created | Jul 9, 2026 | Mar 31, 2026 |