Compare/Gemini 2.5 Pro Preview (May' 25) vs Gemini 3 Flash Preview (Reasoning)

Gemini 2.5 Pro Preview (May' 25)vsGemini 3 Flash Preview (Reasoning)

Side-by-side comparison of pricing, 12 benchmarks, and generation speed.

Google

Gemini 2.5 Pro Preview (May' 25)

Input
$1.25/M
Output
$10/M
Speed
TTFT
Google

Gemini 3 Flash Preview (Reasoning)

Input
$0.5/M
Output
$3/M
Speed
180 tok/s
TTFT
6.33s

Winner by Category

Cheaper
Gemini 3 Flash Preview (Reasoning)
Faster (tok/s)
Gemini 3 Flash Preview (Reasoning)
Lower Latency
Gemini 2.5 Pro Preview (May' 25)
Benchmarks (1-11)
Gemini 3 Flash Preview (Reasoning)

Pricing Comparison

MetricGemini 2.5 Pro Preview (May' 25)Gemini 3 Flash Preview (Reasoning)
Input ($/M tokens)$1.25$0.5
Output ($/M tokens)$10$3
Cost for 1M input + 100K output tokens:
Gemini 2.5 Pro Preview (May' 25)$2.25
Gemini 3 Flash Preview (Reasoning)$0.80

Speed Comparison

Output Speed (tokens/s) — higher is better
Gemini 2.5 Pro Preview (May' 25)
Gemini 3 Flash Preview (Reasoning)
180 tok/s
Time to First Token (seconds) — lower is better
Gemini 2.5 Pro Preview (May' 25)
Gemini 3 Flash Preview (Reasoning)
6.33s

Benchmark Comparison

Data from Artificial Analysis API — 12 benchmarks

Intelligence Index
29.546.4
Coding Index
42.6
Math Index
97.0
GPQA Diamond
82.2%89.8%
MMLU-Pro
83.7%89.0%
LiveCodeBench
77.0%90.8%
AIME 2025
97.0%
MATH-500
98.6%
Humanity's Last Exam
15.4%34.7%
SciCode
41.6%50.6%
IFBench
78.0%
TerminalBench
38.6%
Gemini 2.5 Pro Preview (May' 25)1 wins
11 winsGemini 3 Flash Preview (Reasoning)

Frequently Asked Questions

Which is cheaper, Gemini 2.5 Pro Preview (May' 25) or Gemini 3 Flash Preview (Reasoning)?

Gemini 3 Flash Preview (Reasoning) is cheaper overall. Its blended price (3:1 input/output ratio) is $1.13/M tokens vs $3.44/M for Gemini 2.5 Pro Preview (May' 25).

Which model performs better on benchmarks?

Gemini 3 Flash Preview (Reasoning) wins 11 out of 12 benchmarks compared to 1 for Gemini 2.5 Pro Preview (May' 25). See the detailed benchmark chart above for per-category results.

Which is faster for real-time applications?

Gemini 3 Flash Preview (Reasoning) generates tokens faster at 180 tok/s vs 0 tok/s. Gemini 2.5 Pro Preview (May' 25) also has lower time-to-first-token (0.00s vs 6.33s).

When should I use Gemini 2.5 Pro Preview (May' 25) vs Gemini 3 Flash Preview (Reasoning)?

Choose based on your priorities: Gemini 3 Flash Preview (Reasoning) for lower cost, Gemini 3 Flash Preview (Reasoning) for stronger benchmark performance, and Gemini 3 Flash Preview (Reasoning) for faster generation. For latency-sensitive apps, check the TTFT comparison above.