Compare/Gemini 2.5 Flash Preview (Sep '25) (Reasoning) vs gpt-oss-20B (low)

Gemini 2.5 Flash Preview (Sep '25) (Reasoning)vsgpt-oss-20B (low)

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

Google

Gemini 2.5 Flash Preview (Sep '25) (Reasoning)

Input
$0/M
Output
$0/M
Speed
TTFT
OpenAI

gpt-oss-20B (low)

Input
$0.06/M
Output
$0.2/M
Speed
265 tok/s
TTFT
0.42s

Winner by Category

Cheaper
Gemini 2.5 Flash Preview (Sep '25) (Reasoning)
Faster (tok/s)
gpt-oss-20B (low)
Lower Latency
Gemini 2.5 Flash Preview (Sep '25) (Reasoning)
Benchmarks (10-1)
Gemini 2.5 Flash Preview (Sep '25) (Reasoning)

Pricing Comparison

MetricGemini 2.5 Flash Preview (Sep '25) (Reasoning)gpt-oss-20B (low)
Input ($/M tokens)$0$0.06
Output ($/M tokens)$0$0.2
Cost for 1M input + 100K output tokens:
Gemini 2.5 Flash Preview (Sep '25) (Reasoning)$0.00
gpt-oss-20B (low)$0.08

Speed Comparison

Output Speed (tokens/s) — higher is better
Gemini 2.5 Flash Preview (Sep '25) (Reasoning)
gpt-oss-20B (low)
265 tok/s
Time to First Token (seconds) — lower is better
Gemini 2.5 Flash Preview (Sep '25) (Reasoning)
gpt-oss-20B (low)
0.42s

Benchmark Comparison

Data from Artificial Analysis API — 12 benchmarks

Intelligence Index
31.120.8
Coding Index
24.614.4
Math Index
78.362.3
GPQA Diamond
79.3%61.1%
MMLU-Pro
84.2%71.8%
LiveCodeBench
71.3%65.2%
AIME 2025
78.3%62.3%
MATH-500
Humanity's Last Exam
12.7%5.1%
SciCode
40.5%34.0%
IFBench
52.3%57.8%
TerminalBench
16.7%4.5%
Gemini 2.5 Flash Preview (Sep '25) (Reasoning)10 wins
1 winsgpt-oss-20B (low)

Frequently Asked Questions

Which is cheaper, Gemini 2.5 Flash Preview (Sep '25) (Reasoning) or gpt-oss-20B (low)?

Gemini 2.5 Flash Preview (Sep '25) (Reasoning) is cheaper overall. Its blended price (3:1 input/output ratio) is $0.00/M tokens vs $0.10/M for gpt-oss-20B (low).

Which model performs better on benchmarks?

Gemini 2.5 Flash Preview (Sep '25) (Reasoning) wins 10 out of 12 benchmarks compared to 1 for gpt-oss-20B (low). See the detailed benchmark chart above for per-category results.

Which is faster for real-time applications?

gpt-oss-20B (low) generates tokens faster at 265 tok/s vs 0 tok/s. Gemini 2.5 Flash Preview (Sep '25) (Reasoning) also has lower time-to-first-token (0.00s vs 0.42s).

When should I use Gemini 2.5 Flash Preview (Sep '25) (Reasoning) vs gpt-oss-20B (low)?

Choose based on your priorities: Gemini 2.5 Flash Preview (Sep '25) (Reasoning) for lower cost, Gemini 2.5 Flash Preview (Sep '25) (Reasoning) for stronger benchmark performance, and gpt-oss-20B (low) for faster generation. For latency-sensitive apps, check the TTFT comparison above.