Gemini 2.5 Flash vs o3
Side-by-side benchmark comparison across coding, math, reasoning, speed, and pricing.
o3 by OpenAI wins on 11 of 17 benchmarks against Gemini 2.5 Flash by Google, which leads on 6. 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, o3 scores 1380 on Chatbot Arena ELO compared to Gemini 2.5 Flash's 1320, while o3 scores 84.0% on MMLU-Pro compared to Gemini 2.5 Flash's 73.0%.
Coding: In coding, o3 scores 90.0% on HumanEval+ compared to Gemini 2.5 Flash's 82.0%, while o3 scores 69.1% on SWE-bench Verified compared to Gemini 2.5 Flash's 38.0%, while o3 scores 70.0% on LiveCodeBench compared to Gemini 2.5 Flash's 42.0%.
Math: In math, o3 scores 96.0% on MATH compared to Gemini 2.5 Flash's 76.0%, while o3 scores 98.5% on GSM8K compared to Gemini 2.5 Flash's 91.0%.
Reasoning: In reasoning, o3 scores 83.3% on GPQA Diamond compared to Gemini 2.5 Flash's 48.0%, while o3 scores 75.7% on ARC-AGI compared to Gemini 2.5 Flash's 25.0%, while o3 scores 95.8% on BBH compared to Gemini 2.5 Flash's 89.8%.
Context: In context, Gemini 2.5 Flash scores 1.0M on Context Length compared to o3's 200K.
Multimodal: In multimodal, o3 scores 86.8% on MathVista compared to Gemini 2.5 Flash's 75.5%.
Pricing Comparison
Gemini 2.5 Flash costs $0.30/1M input tokens and $2.5/1M output tokens, while o3 costs $2.0/1M input and $8.0/1M 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 o3's 40 tok/s, and the time to first token is 410 ms for Gemini 2.5 Flash versus 800 ms for o3. 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, o3 is the stronger choice.
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Gemini 2.5 Flash vs o3 — FAQ
Which is better, Gemini 2.5 Flash or o3?
o3 wins on more benchmarks overall (11 vs 6). However, the best choice depends on your specific needs — each model excels in different areas.
How does Gemini 2.5 Flash compare to o3 for coding?
o3 is better for coding, scoring 69.1% 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 o3?
Yes, Gemini 2.5 Flash is cheaper. Gemini 2.5 Flash costs $0.30/1M input and $2.5/1M output tokens. o3 costs $2.0/1M input and $8.0/1M output tokens.
Which is faster, Gemini 2.5 Flash or o3?
Gemini 2.5 Flash is faster, generating output at 251 tok/s compared to 40 tok/s. Faster output speed means shorter wait times for API responses.
What benchmarks does the Gemini 2.5 Flash vs o3 comparison cover?
This comparison covers 17 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.