Gemini 2.5 Flash vs GPT-5.1
Side-by-side benchmark comparison across coding, math, reasoning, speed, and pricing.
GPT-5.1 by OpenAI wins on 10 of 15 benchmarks against Gemini 2.5 Flash by Google, which leads on 5. This head-to-head comparison covers coding, math, reasoning, speed, and pricing metrics from our benchmark data.
Category-by-Category Breakdown
General Intelligence: In general intelligence, GPT-5.1 scores 1464 on Chatbot Arena ELO compared to Gemini 2.5 Flash's 1320, while GPT-5.1 scores 86.0% on MMLU-Pro compared to Gemini 2.5 Flash's 73.0%.
Coding: In coding, GPT-5.1 scores 93.0% on HumanEval+ compared to Gemini 2.5 Flash's 82.0%, while GPT-5.1 scores 76.3% on SWE-bench Verified compared to Gemini 2.5 Flash's 38.0%, while GPT-5.1 scores 82.0% on LiveCodeBench compared to Gemini 2.5 Flash's 42.0%.
Math: In math, GPT-5.1 scores 95.0% on MATH compared to Gemini 2.5 Flash's 76.0%, while GPT-5.1 scores 98.5% on GSM8K compared to Gemini 2.5 Flash's 91.0%.
Reasoning: In reasoning, GPT-5.1 scores 88.1% on GPQA Diamond compared to Gemini 2.5 Flash's 48.0%, while GPT-5.1 scores 50.0% on ARC-AGI compared to Gemini 2.5 Flash's 25.0%.
Context: In context, Gemini 2.5 Flash scores 1.0M on Context Length compared to GPT-5.1's 400K.
Pricing Comparison
Gemini 2.5 Flash costs $0.30/1M input tokens and $2.5/1M output tokens, while GPT-5.1 costs $1.3/1M input and $10.0/1M output. Gemini 2.5 Flash is the more affordable option for API usage.
Speed Comparison
Gemini 2.5 Flash generates output at 251 tok/s compared to GPT-5.1's 95 tok/s, and the time to first token is 410 ms for Gemini 2.5 Flash versus 350 ms for GPT-5.1. Gemini 2.5 Flash delivers faster throughput.
Verdict
For developers prioritizing affordability and speed, Gemini 2.5 Flash has the edge. For those who value coding and general intelligence and math, GPT-5.1 is the stronger choice.
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Gemini 2.5 Flash vs GPT-5.1 — FAQ
Which is better, Gemini 2.5 Flash or GPT-5.1?
GPT-5.1 wins on more benchmarks overall (10 vs 5). However, the best choice depends on your specific needs — each model excels in different areas.
How does Gemini 2.5 Flash compare to GPT-5.1 for coding?
GPT-5.1 is better for coding, scoring 76.3% on SWE-bench Verified compared to 38.0%. SWE-bench tests real-world software engineering by resolving actual GitHub issues.
Is Gemini 2.5 Flash cheaper than GPT-5.1?
Yes, Gemini 2.5 Flash is cheaper. Gemini 2.5 Flash costs $0.30/1M input and $2.5/1M output tokens. GPT-5.1 costs $1.3/1M input and $10.0/1M output tokens.
Which is faster, Gemini 2.5 Flash or GPT-5.1?
Gemini 2.5 Flash is faster, generating output at 251 tok/s compared to 95 tok/s. Faster output speed means shorter wait times for API responses.
What benchmarks does the Gemini 2.5 Flash vs GPT-5.1 comparison cover?
This comparison covers 15 benchmarks including Chatbot Arena ELO, MMLU-Pro, HumanEval+, MATH, GPQA Diamond, SWE-bench Verified, Output Speed, LiveCodeBench, and more. Metrics span general intelligence, coding, math, reasoning, speed, and cost categories.