Compare AI models

Specifications
Context windowHow much text the model can hold in mind at once — your question, any documents you attach, the conversation so far, and its own reply. Go past it and the earliest part falls out of view.
1M—
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$1.25
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.
$25.00$2.50
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$0.20
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.
$5.00Amazon Bedrock—
Cheapest outputLowest output rate across every provider on OpenRouter, the lab included. May come from a different provider than the cheapest input.
$25.00Amazon Bedrock—
$2,250Anthropic list price$375SpaceXSI 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.
95%56%
SWE-Bench VerifiedCoding — Real coding tasks pulled from open-source projects — the AI has to find and fix actual bugs. A human-checked version of the original SWE-Bench. Higher is better.
88.6%76.7%
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.
72.08%53.3%
Overview
CompanyAnthropicSpaceXSI
Release dateMay 28 2026Feb 17 2026
AccessClosedClosed
Model detailsView modelView model

Frequently asked questions

Claude Opus 4.8 leads Grok 4.20 Beta on 3 of the 3 benchmarks they both report (BullshitBench v2, SWE-Bench Verified, ARC-AGI-2). Grok 4.20 Beta is cheaper on both input and output: $1.25 vs $5.00 per million input tokens, and $2.50 vs $25.00 per million output tokens. Figures are base-tier rates. Grok 4.20 Beta shipped 100 days before Claude Opus 4.8, 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, Claude Opus 4.8 leads at 95% vs Grok 4.20 Beta at 56%. On SWE-Bench Verified, Claude Opus 4.8 leads at 88.6% vs Grok 4.20 Beta at 76.7%. On ARC-AGI-2, Claude Opus 4.8 leads at 72.08% vs Grok 4.20 Beta at 53.3%.