tokevenGPTvsGPT
GPT 5.1 vs GPT 6 Luna
Side-by-side comparison of pricing, task quality, and projected cost at higher scale.
Pricing
Side-by-side pricing
GPT 5.1
Mid-tierGPT 6 Luna
Fast / BudgetInput $/MTok
$1.25
$0.10
Output $/MTok
$10.00
$0.50
Cache discount
90% off
90% off
Context
272K
922K
Quality
Task confidence comparison
Confidence score from zero to one hundred by task type, where higher is better.
Code Generation
0
vs
0
Code Review
0
vs
0
Summarization
0
vs
0
Q&A
0
vs
0
Extraction
0
vs
0
Reasoning
0
vs
0
Classification
0
vs
0
Creative Writing
0
vs
0
GPT 5.1
GPT 6 Luna
Guidance
When to use GPT 5.1 vs GPT 6 Luna
Choose GPT 5.1 when...
- Similar performance; consider provider preference or ecosystem fit.
Choose GPT 6 Luna when...
- -Cost matters: 92% cheaper on input tokens
- -You need a larger context window (922K vs 272K)
At scale
Cost at scale
Estimated cost assuming a seventy percent input and thirty percent output token split.
GPT 5.1
GPT 6 Luna
100K tokens
$0.39
$0.02Cheaper
1M tokens
$3.88
$0.36Cheaper
10M tokens
$38.75
$3.65Cheaper
FAQ
When should I use GPT 5.1 instead of GPT 6 Luna?
GPT 5.1 and GPT 6 Luna perform similarly across all tracked tasks. Pick based on pricing and provider preference.
Is GPT 6 Luna cheaper than GPT 5.1?
Yes. GPT 6 Luna input costs $0.10/MTok vs $1.25/MTok for GPT 5.1, saving 92% on input.
What are the context window sizes for GPT 5.1 and GPT 6 Luna?
GPT 5.1 has a 272K token context window. GPT 6 Luna has a 922K 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 5.1 and GPT 6 Luna 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.