claude-sonnet-4-5-20250929 vs gemini-2.5-pro Benchmark Comparison

Direct benchmark comparison between claude-sonnet-4-5-20250929 and gemini-2.5-pro based on LMArena Elo and the latest 2026 API pricing.

Direct Technical & Pricing Comparison

Frontier Model	LMArena Elo	API Cost (1M)	Throughput
claude-sonnet-4-5-20250929	1451	$0.000003	37
gemini-2.5-pro	1448	$0.00000125	89

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

Comparison Summary: These models are highly competitive, with a negligible Elo gap of only 3 points. The choice between them should be driven by specific API features or provider preference. However, neither model is currently Pareto-optimal. Developers looking for peak efficiency should investigate gpt-5.2-chat-latest-20260210, which offers a superior benchmark-to-price ratio.