Compare/Grok 4.1 Fast (Reasoning) vs gpt-oss-120b (low)

Grok 4.1 Fast (Reasoning)vsgpt-oss-120b (low)

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

xAI

Grok 4.1 Fast (Reasoning)

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

gpt-oss-120b (low)

Input
$0.15/M
Output
$0.6/M
Speed
274 tok/s
TTFT
0.51s

Winner by Category

Cheaper
Grok 4.1 Fast (Reasoning)
Faster (tok/s)
gpt-oss-120b (low)
Lower Latency
Grok 4.1 Fast (Reasoning)
Benchmarks (10-1)
Grok 4.1 Fast (Reasoning)

Pricing Comparison

MetricGrok 4.1 Fast (Reasoning)gpt-oss-120b (low)
Input ($/M tokens)$0$0.15
Output ($/M tokens)$0$0.6
Cost for 1M input + 100K output tokens:
Grok 4.1 Fast (Reasoning)$0.00
gpt-oss-120b (low)$0.21

Speed Comparison

Output Speed (tokens/s) — higher is better
Grok 4.1 Fast (Reasoning)
gpt-oss-120b (low)
274 tok/s
Time to First Token (seconds) — lower is better
Grok 4.1 Fast (Reasoning)
gpt-oss-120b (low)
0.51s

Benchmark Comparison

Data from Artificial Analysis API — 12 benchmarks

Intelligence Index
38.624.5
Coding Index
30.915.5
Math Index
89.366.7
GPQA Diamond
85.3%67.2%
MMLU-Pro
85.4%77.5%
LiveCodeBench
82.2%70.7%
AIME 2025
89.3%66.7%
MATH-500
Humanity's Last Exam
17.6%5.2%
SciCode
44.2%36.0%
IFBench
52.7%58.3%
TerminalBench
24.2%5.3%
Grok 4.1 Fast (Reasoning)10 wins
1 winsgpt-oss-120b (low)

Frequently Asked Questions

Which is cheaper, Grok 4.1 Fast (Reasoning) or gpt-oss-120b (low)?

Grok 4.1 Fast (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 (low).

Which model performs better on benchmarks?

Grok 4.1 Fast (Reasoning) wins 10 out of 12 benchmarks compared to 1 for gpt-oss-120b (low). See the detailed benchmark chart above for per-category results.

Which is faster for real-time applications?

gpt-oss-120b (low) generates tokens faster at 274 tok/s vs 0 tok/s. Grok 4.1 Fast (Reasoning) also has lower time-to-first-token (0.00s vs 0.51s).

When should I use Grok 4.1 Fast (Reasoning) vs gpt-oss-120b (low)?

Choose based on your priorities: Grok 4.1 Fast (Reasoning) for lower cost, Grok 4.1 Fast (Reasoning) for stronger benchmark performance, and gpt-oss-120b (low) for faster generation. For latency-sensitive apps, check the TTFT comparison above.