GPT-5.1 vs GPT-5.5
Side-by-side benchmark comparison across coding, math, reasoning, speed, and pricing.
GPT-5.5 by OpenAI wins on 5 of 9 benchmarks against GPT-5.1 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, GPT-5.5 scores 74.9 on AA Coding Index compared to GPT-5.1's 49.4, while GPT-5.5 scores 1272 on Design Arena ELO compared to GPT-5.1's 1158, while GPT-5.5 scores 1269 on Website Arena ELO compared to GPT-5.1's 1179.
Reasoning: In reasoning, GPT-5.5 scores 93.8% on GPQA Diamond compared to GPT-5.1's 86.2%, while GPT-5.1 scores 75.7% on τ²-Bench Airline compared to GPT-5.5's 75.3%.
Context: In context, GPT-5.5 scores 1.1M on Context Length compared to GPT-5.1's 400K.
Pricing Comparison
GPT-5.1 costs $1.3/1M input tokens and $10.0/1M output tokens, while GPT-5.5 costs $5.0/1M input and $30.0/1M output. GPT-5.1 is the more affordable option for API usage.
Verdict
GPT-5.1 leads across the board in affordability, making it the stronger overall choice in this comparison.
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GPT-5.1 vs GPT-5.5 — FAQ
Which is better, GPT-5.1 or GPT-5.5?
GPT-5.5 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 GPT-5.1 compare to GPT-5.5 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-5.5?
Yes, GPT-5.1 is cheaper. GPT-5.1 costs $1.3/1M input and $10.0/1M output tokens. GPT-5.5 costs $5.0/1M input and $30.0/1M output tokens.
Which is faster, GPT-5.1 or GPT-5.5?
Output speed data is not available for both models. Check the speed section of the comparison above for available performance data.
What benchmarks does the GPT-5.1 vs GPT-5.5 comparison cover?
This comparison covers 9 benchmarks including GPQA Diamond, Input Cost, Output Cost, Context Length, AA Coding Index, Cached Input Cost, Design Arena ELO, τ²-Bench Airline, and more. Metrics span general intelligence, coding, math, reasoning, speed, and cost categories.