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.
1M1.05M
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.
—$30.00
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.
—$180.00
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.
—$15.00OpenAI
Cheapest outputLowest output rate across every provider on OpenRouter, the lab included. May come from a different provider than the cheapest input.
—$90.00OpenAI
—$15,000OpenAI list price
Benchmarks
Humanity's Last Exam · no toolsMultidisciplinary reasoning — Humanity's Last Exam — extremely hard expert questions across many subjects, written so you can't just look up the answer. “No tools” means the AI answers on its own. Higher is better.
56.8%42.7%
Humanity's Last Exam · with toolsMultidisciplinary reasoning — Humanity's Last Exam — extremely hard expert questions across many subjects. “With tools” means the AI is allowed to search the web or run code while answering. Higher is better.
64.7%58.7%
GPQA DiamondScience — Graduate-level science questions in biology, physics, and chemistry — hard enough that subject-matter PhDs score around 65%. Higher is better.
94.5%94.4%
Overview
CompanyAnthropicOpenAI
Release dateApr 7 2026Mar 5 2026
AccessClosedClosed
Model detailsView modelView model

Frequently asked questions

Claude Mythos Preview leads GPT-5.4-Pro on 3 of the 3 benchmarks they both report (Humanity's Last Exam, GPQA Diamond). Only GPT-5.4-Pro has a verified first-party price for an available API: $30.00 per million input tokens and $180.00 per million output tokens. No currently available pay-as-you-go API rate is tracked for Claude Mythos Preview. GPT-5.4-Pro shipped 33 days before Claude Mythos Preview, so benchmark comparisons should account for the intervening progress.

Context windows are 1M (Claude Mythos Preview) vs 1.05M (GPT-5.4-Pro).

On Humanity's Last Exam · no tools, Claude Mythos Preview leads at 56.8% vs GPT-5.4-Pro at 42.7%. On Humanity's Last Exam · with tools, Claude Mythos Preview leads at 64.7% vs GPT-5.4-Pro at 58.7%. On GPQA Diamond, Claude Mythos Preview leads at 94.5% vs GPT-5.4-Pro at 94.4%.