Claude Mythos 5.1 vs Gemini 3.8 Flash

Claude Mythos 5.1 from Anthropic and Gemini 3.8 Flash from Google, side by side. Every figure comes from the model registry. No markup on model usage: you pay the provider's list price.

Side-by-side comparison of Claude Mythos 5.1, Gemini 3.8 Flash

Attribute	Claude Mythos 5.1	Gemini 3.8 Flash
Provider	Anthropic	Google
Model id	anthropic/claude-mythos-5-1	google/gemini-3.8-flash
Status	Available via Safeguard	Available via Safeguard
Input / 1M tokens	$10	$0.75
Output / 1M tokens	$50	$3.75
Price notes	Base price, same as Claude Fable 5.1. Anthropic requires the organization to be verified through one of its programs before use. Cache hits $0.25/1M. Batch 50% off.	Paid tier. $0.75 in / $3.75 out (output includes thinking tokens) through 2026-12-31, rises to $1.50 / $7.50 from 2027-01-01.
Context	1M	1.05M
Parameters	Not published	Not published
Max output	128,000 tokens	65,536 tokens
Modality	Text and image	Text and image
Weights	Closed	Closed
Zero data retention	Not offered	Not offered
Prompts go to	Anthropic (global routing by default)	Google (Gemini Developer API)
Retention	Not used for model training without express permission. Claude Mythos 5.1 is a Covered Model that requires 30-day data retention and is not available under ZDR unless Anthropic expressly authorizes it	Paid tier: prompts and responses not used to improve Google products, but logged for a limited period for abuse monitoring, free tier content may be used to improve products
Region	Global by default, US-only inference via inference_geo at 1.1x pricing (Claude 4.6 and later)	No region guarantee, data may be stored transiently or cached in any country where Google operates. Google points ZDR and enterprise processing needs to Vertex AI (Gemini Enterprise Agent Platform)
Price checked	2026-10-08	2026-10-08

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