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GPT-5.5 vs Gemini 2.5 Pro
Side-by-side intelligence, speed, price, benchmarks, strengths and weaknesses for GPT-5.5 and Gemini 2.5 Pro — refreshed monthly.
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Spec
GPT-5.5
Gemini 2.5 Pro
Intelligence index↑ better
Winner82
78
Speed↑ better
95 tok/s
Winner110 tok/s
Time to first token↓ better
Winner0.42 s
0.7 s
Context window↑ better
400k
Winner2M
Max output↑ better
16k
Winner66k
Input price↓ better
$5.00 / 1M tokens
Winner$1.25 / 1M tokens
Output price↓ better
$15.00 / 1M tokens
Winner$5.00 / 1M tokens
Blended price↓ better
$7.50 / 1M tokens
Winner$2.19 / 1M tokens
License
Proprietary
Proprietary
Input modalities
text, image
text, image, audio, video
Output modalities
text
text
Benchmark showdown
MMLU
GPT-5.5
90.2
Gemini 2.5 Pro
89.5
MMLU Pro
GPT-5.5
78.0
Gemini 2.5 Pro
78.5
GPQA
GPT-5.5
62.5
Gemini 2.5 Pro
66.0
MATH
GPT-5.5
89.1
Gemini 2.5 Pro
91.0
HumanEval
GPT-5.5
93.0
Gemini 2.5 Pro
91.5
Strengths, weaknesses and best-for
GPT-5.5
Strengths
- Best-in-class reasoning
- Huge 400k context
- Strong tool use and agents
Weaknesses
- Expensive vs Sonnet for non-reasoning tasks
- Higher latency than gpt-5.5-mini
Best for
- Agentic workflows
- Complex coding
- Hard math & research
Gemini 2.5 Pro
Strengths
- 2M context
- Native video understanding
- Strong on math
Weaknesses
- Output ceiling lower than competitors
Best for
- Whole-codebase analysis
- Long-doc workflows
- Video QA
Quick verdict
- Pick GPT-5.5 if you want it smarter.
- Pick Gemini 2.5 Pro if you want it faster, cheaper and longer context.
Auto-generated from the spec sheet. Always validate on your own evals.
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