Gemini 1.5 Pro vs Gemini 2.5 Flash Preview 05-20 (thinking)
Compare Gemini 1.5 Pro and Gemini 2.5 Flash Preview 05-20 (thinking), both from Google AI, context windows of 1.0M vs 1.0M, tested across 2 shared challenges. Updated June 2026.
Which is better, Gemini 1.5 Pro or Gemini 2.5 Flash Preview 05-20 (thinking)?
Gemini 1.5 Pro and Gemini 2.5 Flash Preview 05-20 (thinking) are both competitive models. Gemini 1.5 Pro costs $3.5/M input tokens vs $0.15/M for Gemini 2.5 Flash Preview 05-20 (thinking). Context windows: 1000K vs 1049K tokens. Compare their real outputs side by side below.
Key Differences Between Gemini 1.5 Pro and Gemini 2.5 Flash Preview 05-20 (thinking)
Gemini 1.5 Pro is made by google while Gemini 2.5 Flash Preview 05-20 (thinking) is from google. Gemini 1.5 Pro has a 1000K token context window compared to Gemini 2.5 Flash Preview 05-20 (thinking)'s 1049K. On pricing, Gemini 1.5 Pro costs $3.5/M input tokens vs $0.15/M for Gemini 2.5 Flash Preview 05-20 (thinking).
Per 1M tokens
Gemini 2.5 Flash Preview 05-20 (thinking) is cheaper on both — 23× input, 3.0× output
No community votes yet. On paper, these are closely matched - try both with your actual task to see which fits your workflow.
Gemini 2.5 Flash Preview 05-20 (thinking) is 3.0x cheaper per token — worth considering if cost matters.
Style Comparison
Gemini 1.5 Pro uses 79.5x more hedging
