Compare AI models

API pricing
Input price
$0.20$1.25
Output price
$1.20$2.50
Cached input price
$0.02$0.20
Cheapest input
$0.10OpenAI—
Cheapest output
$0.60OpenAI—
Benchmarks
BullshitBench v2
41%56%
ARC-AGI-2
59.54%53.3%
Overview
CompanyOpenAISpaceXAI
Release dateJun 26 2026Feb 17 2026
AccessClosedClosed
Model detailsView modelView model

Frequently asked questions

GPT-5.6 Luna and Grok 4.20 Beta are evenly matched across the 2 benchmarks they both report (BullshitBench v2, ARC-AGI-2). GPT-5.6 Luna is cheaper on both input and output: $0.20 vs $1.25 per million input tokens, and $1.20 vs $2.50 per million output tokens. Figures are base-tier rates. Grok 4.20 Beta shipped 129 days before GPT-5.6 Luna, so benchmark comparisons should account for the intervening progress.

Published specifications for these two models are limited — see each model page for the latest details.

On BullshitBench v2, Grok 4.20 Beta leads at 56% vs GPT-5.6 Luna at 41%. On ARC-AGI-2, GPT-5.6 Luna leads at 59.54% vs Grok 4.20 Beta at 53.3%.