deepseek-v4-flash-thinking vs grok-4.20-beta-0309-reasoning Benchmark Comparison

Direct benchmark comparison between deepseek-v4-flash-thinking and grok-4.20-beta-0309-reasoning based on LMArena Elo and the latest 2026 API pricing.

Direct Technical & Pricing Comparison

Frontier Model	LMArena Elo	API Cost (1M)	Throughput
deepseek-v4-flash-thinking	1439	$1.4e-7	48
grok-4.20-beta-0309-reasoning	1479	$0.000002	50

*These models represent the Pareto Frontier (optimal cost-to-performance).*

Comparison Summary: grok-4.20-beta-0309-reasoning is the more capable model in this pair, leading by 40 Elo points. However, neither model is currently Pareto-optimal. Developers looking for peak efficiency should investigate claude-opus-4-7-thinking, which offers a superior benchmark-to-price ratio.