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.
400k500k
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.
—$2.00
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.
—$6.00
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.
—$0.30
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.
—$2.00xAI
Cheapest outputLowest output rate across every provider on OpenRouter, the lab included. May come from a different provider than the cheapest input.
—$6.00xAI
—$700SpaceXSI 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.
32%55%
Overview
CompanyOpenAISpaceXSI
Release dateNov 13 2025Jul 8 2026
AccessClosedClosed
Model detailsView modelView model

Frequently asked questions

Grok 4.5 leads GPT-5.1-Codex on 1 of the 1 benchmark they both report (BullshitBench v2). Only Grok 4.5 has a verified first-party price for an available API: $2.00 per million input tokens and $6.00 per million output tokens. No currently available pay-as-you-go API rate is tracked for GPT-5.1-Codex. GPT-5.1-Codex shipped 237 days before Grok 4.5, so benchmark comparisons should account for the intervening progress.

Context windows are 400k (GPT-5.1-Codex) vs 500k (Grok 4.5).

On BullshitBench v2, Grok 4.5 leads at 55% vs GPT-5.1-Codex at 32%.