Compare/Gemini 3.5 Flash (high) vs Gemini 3 Flash Preview (Reasoning)

Gemini 3.5 Flash (high)vsGemini 3 Flash Preview (Reasoning)

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

Google

Gemini 3.5 Flash (high)

Input
$1.5/M
Output
$9/M
Speed
251 tok/s
TTFT
16.51s
Google

Gemini 3 Flash Preview (Reasoning)

Input
$0.5/M
Output
$3/M
Speed
208 tok/s
TTFT
5.86s

Winner by Category

Cheaper
Gemini 3 Flash Preview (Reasoning)
Faster (tok/s)
Gemini 3.5 Flash (high)
Lower Latency
Gemini 3 Flash Preview (Reasoning)
Benchmarks (6-5)
Gemini 3.5 Flash (high)

Pricing Comparison

MetricGemini 3.5 Flash (high)Gemini 3 Flash Preview (Reasoning)
Input ($/M tokens)$1.5$0.5
Output ($/M tokens)$9$3
Cost for 1M input + 100K output tokens:
Gemini 3.5 Flash (high)$2.40
Gemini 3 Flash Preview (Reasoning)$0.80

Speed Comparison

Output Speed (tokens/s) — higher is better
Gemini 3.5 Flash (high)
251 tok/s
Gemini 3 Flash Preview (Reasoning)
208 tok/s
Time to First Token (seconds) — lower is better
Gemini 3.5 Flash (high)
16.51s
Gemini 3 Flash Preview (Reasoning)
5.86s

Benchmark Comparison

Data from Artificial Analysis API — 12 benchmarks

Intelligence Index
50.237.8
Coding Index
70.1
Math Index
97.0
GPQA Diamond
92.2%89.8%
MMLU-Pro
89.0%
LiveCodeBench
90.8%
AIME 2025
97.0%
MATH-500
Humanity's Last Exam
41.0%34.7%
SciCode
53.1%50.6%
IFBench
76.3%78.0%
TerminalBench
40.9%38.6%
Gemini 3.5 Flash (high)6 wins
5 winsGemini 3 Flash Preview (Reasoning)

Frequently Asked Questions

Which is cheaper, Gemini 3.5 Flash (high) 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 $3.38/M for Gemini 3.5 Flash (high).

Which model performs better on benchmarks?

Gemini 3.5 Flash (high) wins 6 out of 12 benchmarks compared to 5 for Gemini 3 Flash Preview (Reasoning). See the detailed benchmark chart above for per-category results.

Which is faster for real-time applications?

Gemini 3.5 Flash (high) generates tokens faster at 251 tok/s vs 208 tok/s. However, Gemini 3 Flash Preview (Reasoning) has lower time-to-first-token (5.86s vs 16.51s).

When should I use Gemini 3.5 Flash (high) vs Gemini 3 Flash Preview (Reasoning)?

Choose based on your priorities: Gemini 3 Flash Preview (Reasoning) for lower cost, Gemini 3.5 Flash (high) for stronger benchmark performance, and Gemini 3.5 Flash (high) for faster generation. For latency-sensitive apps, check the TTFT comparison above.