Compare AI models

Specifications
Context windowHow much information the model can work with in one request, measured in tokens — pieces of words or other data. This includes your question, attachments, conversation and reply. Limits can vary by model variant and provider.
1.05M1.05M
API pricingUSD per 1M tokens · lower wins · base tier
Input priceWhat you pay for everything you send the model — your question, plus any documents or earlier conversation you include with it.
$5.00$0.10
Output priceWhat you pay for the text the model writes back. It is normally the dearer half: producing an answer costs more than reading one.
$30.00$0.50
Cached input priceA reduced rate for text you send over and over. If every request starts with the same instructions or the same document, the provider keeps a copy ready and charges less to read it again.
$0.50$0.01
Cheapest inputLowest input rate across every provider on OpenRouter, the lab included. The cheapest endpoint may run a quantised build or a shorter context — see "Available from" on the model page.
$2.50OpenAI$0.05OpenAI
Cheapest outputLowest output rate across every provider on OpenRouter, the lab included. May come from a different provider than the cheapest input.
$15.00OpenAI$0.25OpenAI
$2,500OpenAI list price$45.00OpenAI list price
Benchmarks
BullshitBench v2Nonsense detection — Given a confidently-worded but nonsensical prompt, does the AI spot that it makes no sense and push back — instead of playing along and inventing an answer? The score is how often it clearly called out the nonsense. Higher is better.
47%59%
ARC-AGI-2Abstract reasoning — Puzzle-style tests of abstract reasoning and pattern-finding — the kind of thing people find easy but AIs often struggle with. Higher is better.
84.6%59.3%
Overview
CompanyOpenAIOpenAI
Release dateApr 23 2026Sep 22 2026
AccessClosedClosed
Model detailsView modelView model

Frequently asked questions

GPT-5.5 and GPT-6 Luna are evenly matched across the 2 benchmarks they both report (BullshitBench v2, ARC-AGI-2). GPT-6 Luna is cheaper on both input and output: $0.10 vs $5.00 per million input tokens, and $0.50 vs $30.00 per million output tokens. Figures are base-tier rates. GPT-5.5 shipped 152 days before GPT-6 Luna, so benchmark comparisons should account for the intervening progress.

Context windows are 1.05M (GPT-5.5) vs 1.05M (GPT-6 Luna).

On BullshitBench v2, GPT-6 Luna leads at 59% vs GPT-5.5 at 47%. On ARC-AGI-2, GPT-5.5 leads at 84.6% vs GPT-6 Luna at 59.3%.