Head-to-head

GPT-5.6 Luna vs Grok 4.20

This page compares two live catalog candidates across price, context, and workflow fit so buyers can choose between a lower-cost OpenAI route and a larger-context xAI route.

2 modelsLive catalog comparison

PriceCurrent TVP token pricing

ContextCurrent listed window sizes

Fast answer

Choose on the workflow, then use live metrics as the tiebreaker

Choose Luna when lower production cost matters more than maximum context

Data source and freshness

Catalog-backed, not a static price sheet

TVP refreshes this page from the live OpenRouter model catalog. This render used 428 public model records and was synchronized Jul 14, 2026, 9:36 PM UTC. Pricing, availability, and context values can change.

Verify the exact route before sending production traffic, then use the linked model and provider pages as the source for current values. Read the TVP data methodology.

Head to head

Current live model comparison

openai

OpenAI: GPT-5.6 Luna

GPT-5.6 Luna is a fast, cost-efficient model in OpenAI's GPT-5.6 series. It is suited for high-volume, latency-sensitive tasks such as chat, classification, and lightweight agentic workflows, providing capable reasoning for...

Context1,050,000

Input$1.00

Output$6.00

file
image
text
tools
structured

Model details Provider page

x-ai

xAI: Grok 4.20

Grok 4.20 is a reasoning model from xAI with industry-leading speed and agentic tool calling capabilities. It combines the lowest hallucination rate on the market with strict prompt adherance, delivering...

Context2,000,000

Input$1.25

Output$2.50

text
image
file
tools
structured

Model details Provider page

Comparison FAQ

How to use this decision page

Which is cheaper: GPT-5.6 Luna or Grok 4.20?

TVP compares their live token pricing directly on the page so the decision is based on current marketplace data, not older benchmark tables.

Which model is better for long prompts?

Grok 4.20 typically wins on raw context capacity, while Luna can still be the better fit when cost discipline matters more than maximum prompt size.