GPT-5.1 vs GPT-OSS 120B
Side-by-side benchmark comparison across coding, math, reasoning, speed, and pricing.
GPT-5.1 by OpenAI wins on 7 of 10 benchmarks against GPT-OSS 120B by OpenAI, which leads on 3. This head-to-head comparison covers coding, math, reasoning, speed, and pricing metrics from our benchmark data.
Category-by-Category Breakdown
Coding: In coding, GPT-5.1 scores 49.4 on AA Coding Index compared to GPT-OSS 120B's 30.4, while GPT-5.1 scores 1158 on Design Arena ELO compared to GPT-OSS 120B's 974, while GPT-5.1 scores 1179 on Website Arena ELO compared to GPT-OSS 120B's 980.
Reasoning: In reasoning, GPT-5.1 scores 86.2% on GPQA Diamond compared to GPT-OSS 120B's 74.9%, while GPT-5.1 scores 75.7% on τ²-Bench Airline compared to GPT-OSS 120B's 64.1%.
Context: In context, GPT-5.1 scores 400K on Context Length compared to GPT-OSS 120B's 131K.
Pricing Comparison
GPT-5.1 costs $1.3/1M input tokens and $10.0/1M output tokens, while GPT-OSS 120B costs $0.04/1M input and $0.17/1M output. GPT-OSS 120B is the more affordable option for API usage.
Speed Comparison
GPT-5.1 generates output at 95 tok/s compared to GPT-OSS 120B's 339 tok/s, and the time to first token is 350 ms for GPT-5.1 versus 440 ms for GPT-OSS 120B. GPT-OSS 120B delivers faster throughput.
Verdict
GPT-OSS 120B leads across the board in affordability, speed, making it the stronger overall choice in this comparison.
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GPT-5.1 vs GPT-OSS 120B — FAQ
Which is better, GPT-5.1 or GPT-OSS 120B?
GPT-5.1 wins on more benchmarks overall (7 vs 3). However, the best choice depends on your specific needs — each model excels in different areas.
How does GPT-5.1 compare to GPT-OSS 120B for coding?
SWE-bench Verified data is not available for both models. Check the detailed comparison charts above for other coding-related metrics.
Is GPT-5.1 cheaper than GPT-OSS 120B?
Yes, GPT-OSS 120B is cheaper. GPT-5.1 costs $1.3/1M input and $10.0/1M output tokens. GPT-OSS 120B costs $0.04/1M input and $0.17/1M output tokens.
Which is faster, GPT-5.1 or GPT-OSS 120B?
GPT-OSS 120B is faster, generating output at 339 tok/s compared to 95 tok/s. Faster output speed means shorter wait times for API responses.
What benchmarks does the GPT-5.1 vs GPT-OSS 120B comparison cover?
This comparison covers 10 benchmarks including GPQA Diamond, Output Speed, Time to First Token, Input Cost, Output Cost, Context Length, AA Coding Index, Design Arena ELO, and more. Metrics span general intelligence, coding, math, reasoning, speed, and cost categories.