Claude Opus 4.5 vs GPT-OSS 120B
Side-by-side benchmark comparison across coding, math, reasoning, speed, and pricing.
Claude Opus 4.5 by Anthropic wins on 5 of 9 benchmarks against GPT-OSS 120B by OpenAI, which leads on 4. This head-to-head comparison covers coding, math, reasoning, speed, and pricing metrics from our benchmark data.
Category-by-Category Breakdown
Coding: In coding, Claude Opus 4.5 scores 1242 on Design Arena ELO compared to GPT-OSS 120B's 974, while Claude Opus 4.5 scores 1259 on Website Arena ELO compared to GPT-OSS 120B's 980.
Reasoning: In reasoning, Claude Opus 4.5 scores 86.5% on GPQA Diamond compared to GPT-OSS 120B's 74.9%, while Claude Opus 4.5 scores 77.0% on τ²-Bench Airline compared to GPT-OSS 120B's 64.1%.
Context: In context, Claude Opus 4.5 scores 200K on Context Length compared to GPT-OSS 120B's 131K.
Pricing Comparison
Claude Opus 4.5 costs $5.0/1M input tokens and $25.0/1M 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
Claude Opus 4.5 generates output at 50 tok/s compared to GPT-OSS 120B's 339 tok/s, and the time to first token is 1700 ms for Claude Opus 4.5 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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Claude Opus 4.5 vs GPT-OSS 120B — FAQ
Which is better, Claude Opus 4.5 or GPT-OSS 120B?
Claude Opus 4.5 wins on more benchmarks overall (5 vs 4). However, the best choice depends on your specific needs — each model excels in different areas.
How does Claude Opus 4.5 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 Claude Opus 4.5 cheaper than GPT-OSS 120B?
Yes, GPT-OSS 120B is cheaper. Claude Opus 4.5 costs $5.0/1M input and $25.0/1M output tokens. GPT-OSS 120B costs $0.04/1M input and $0.17/1M output tokens.
Which is faster, Claude Opus 4.5 or GPT-OSS 120B?
GPT-OSS 120B is faster, generating output at 339 tok/s compared to 50 tok/s. Faster output speed means shorter wait times for API responses.
What benchmarks does the Claude Opus 4.5 vs GPT-OSS 120B comparison cover?
This comparison covers 9 benchmarks including GPQA Diamond, Output Speed, Time to First Token, Input Cost, Output Cost, Context Length, Design Arena ELO, τ²-Bench Airline, and more. Metrics span general intelligence, coding, math, reasoning, speed, and cost categories.