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	$1.12e-7	55
grok-4.20-beta-0309-reasoning	1475	$0.00000125	55

*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 36 Elo points. Specifically, deepseek-v4-flash-thinking is currently on the Pareto line, suggesting it offers better systemic value for its performance tier.