tokevenGPTvsGrok
GPT 5.6 Luna vs Grok 4.20 Reasoning
Side-by-side comparison of pricing, task quality, and projected cost at higher scale.
Pricing
Side-by-side pricing
GPT 5.6 Luna
Fast / BudgetGrok 4.20 Reasoning
Mid-tierInput $/MTok
$0.20
$1.25
Output $/MTok
$1.20
$2.50
Cache discount
90% off
84% off
Context
922K
1,000K
Quality
Task confidence comparison
Confidence score from zero to one hundred by task type, where higher is better.
Code Generation
70
vs
0
Code Review
68
vs
0
Summarization
84
vs
0
Q&A
85
vs
0
Extraction
89
vs
0
Reasoning
63
vs
0
Classification
91
vs
0
Creative Writing
58
vs
0
GPT 5.6 Luna
Grok 4.20 Reasoning
Guidance
When to use GPT 5.6 Luna vs Grok 4.20 Reasoning
Choose GPT 5.6 Luna when...
- -Cost matters: 84% cheaper on input tokens
Choose Grok 4.20 Reasoning when...
- -You need a larger context window (1,000K vs 922K)
- Similar performance; consider provider preference or ecosystem fit.
At scale
Cost at scale
Estimated cost assuming a seventy percent input and thirty percent output token split.
GPT 5.6 Luna
Grok 4.20 Reasoning
100K tokens
$0.05Cheaper
$0.16
1M tokens
$0.82Cheaper
$3.25
10M tokens
$8.20Cheaper
$32.50
FAQ
When should I use GPT 5.6 Luna instead of Grok 4.20 Reasoning?
GPT 5.6 Luna and Grok 4.20 Reasoning perform similarly across all tracked tasks. Pick based on pricing and provider preference.
Is Grok 4.20 Reasoning cheaper than GPT 5.6 Luna?
Grok 4.20 Reasoning input costs $1.25/MTok, which is 525% more than GPT 5.6 Luna at $0.20/MTok.
What are the context window sizes for GPT 5.6 Luna and Grok 4.20 Reasoning?
GPT 5.6 Luna has a 922K token context window. Grok 4.20 Reasoning has a 1,000K token context window.
Go deeper on either model
Per-call cost calculators, provider lineups, and price history for both models on this page.
Other comparisons
How GPT 5.6 Luna and Grok 4.20 Reasoning stack up against the rest of the field.
Track your real costs
Comparisons show estimated costs at list price. The dashboard reveals your real spend and savings.