Compare/Gemini 2.5 Flash Preview (Sep '25) (Reasoning) vs gpt-oss-120B (high)

Gemini 2.5 Flash Preview (Sep '25) (Reasoning)vsgpt-oss-120B (high)

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-120B (high)

Input
$0.15/M
Output
$0.6/M
Speed
236 tok/s
TTFT
0.50s

Winner by Category

Cheaper
Gemini 2.5 Flash Preview (Sep '25) (Reasoning)
Faster (tok/s)
gpt-oss-120B (high)
Lower Latency
Gemini 2.5 Flash Preview (Sep '25) (Reasoning)
Benchmarks (3-8)
gpt-oss-120B (high)

Pricing Comparison

MetricGemini 2.5 Flash Preview (Sep '25) (Reasoning)gpt-oss-120B (high)
Input ($/M tokens)$0$0.15
Output ($/M tokens)$0$0.6
Cost for 1M input + 100K output tokens:
Gemini 2.5 Flash Preview (Sep '25) (Reasoning)$0.00
gpt-oss-120B (high)$0.21

Speed Comparison

Output Speed (tokens/s) — higher is better
Gemini 2.5 Flash Preview (Sep '25) (Reasoning)
gpt-oss-120B (high)
236 tok/s
Time to First Token (seconds) — lower is better
Gemini 2.5 Flash Preview (Sep '25) (Reasoning)
gpt-oss-120B (high)
0.50s

Benchmark Comparison

Data from Artificial Analysis API — 12 benchmarks

Intelligence Index
31.133.3
Coding Index
24.628.6
Math Index
78.393.4
GPQA Diamond
79.3%78.2%
MMLU-Pro
84.2%80.8%
LiveCodeBench
71.3%87.8%
AIME 2025
78.3%93.4%
MATH-500
Humanity's Last Exam
12.7%18.5%
SciCode
40.5%38.9%
IFBench
52.3%69.0%
TerminalBench
16.7%23.5%
Gemini 2.5 Flash Preview (Sep '25) (Reasoning)3 wins
8 winsgpt-oss-120B (high)

Frequently Asked Questions

Which is cheaper, Gemini 2.5 Flash Preview (Sep '25) (Reasoning) or gpt-oss-120B (high)?

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 $0.26/M for gpt-oss-120B (high).

Which model performs better on benchmarks?

gpt-oss-120B (high) wins 8 out of 12 benchmarks compared to 3 for Gemini 2.5 Flash Preview (Sep '25) (Reasoning). See the detailed benchmark chart above for per-category results.

Which is faster for real-time applications?

gpt-oss-120B (high) generates tokens faster at 236 tok/s vs 0 tok/s. Gemini 2.5 Flash Preview (Sep '25) (Reasoning) also has lower time-to-first-token (0.00s vs 0.50s).

When should I use Gemini 2.5 Flash Preview (Sep '25) (Reasoning) vs gpt-oss-120B (high)?

Choose based on your priorities: Gemini 2.5 Flash Preview (Sep '25) (Reasoning) for lower cost, gpt-oss-120B (high) for stronger benchmark performance, and gpt-oss-120B (high) for faster generation. For latency-sensitive apps, check the TTFT comparison above.