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.
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.
$10.00$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.
$50.00$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.
$1.00$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.
$10.00Amazon Bedrock—
Cheapest outputLowest output rate across every provider on OpenRouter, the lab included. May come from a different provider than the cheapest input.
$50.00Amazon Bedrock—
$4,500Anthropic 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.
56%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.
95.5%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.
89.2%53.3%
Overview
CompanyAnthropicSpaceXSI
Release dateJun 9 2026Feb 17 2026
AccessClosedClosed
Model detailsView modelView model

Frequently asked questions

Claude Fable 5 leads Grok 4.20 Beta on 2 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 $10.00 per million input tokens, and $2.50 vs $50.00 per million output tokens. Figures are base-tier rates. Grok 4.20 Beta shipped 112 days before Claude Fable 5, 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, both models score 56%. On SWE-Bench Verified, Claude Fable 5 leads at 95.5% vs Grok 4.20 Beta at 76.7%. On ARC-AGI-2, Claude Fable 5 leads at 89.2% vs Grok 4.20 Beta at 53.3%.