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Spec
GPT-5.5
OpenAI o1
Intelligence index↑ better
Winner82
76
Speed↑ better
Winner95 tok/s
32 tok/s
Time to first token↓ better
Winner0.42 s
12 s
Context window↑ better
Winner400k
200k
Max output↑ better
16k
Winner100k
Input price↓ better
Winner$5.00 / 1M tokens
$15.00 / 1M tokens
Output price↓ better
Winner$15.00 / 1M tokens
$60.00 / 1M tokens
Blended price↓ better
Winner$7.50 / 1M tokens
$26.25 / 1M tokens
License
Proprietary
Proprietary
Input modalities
text, image
text, image
Output modalities
text
text
Benchmark showdown
MMLU
GPT-5.5
90.2
OpenAI o1
91.8
MMLU Pro
GPT-5.5
78.0
OpenAI o1
80.0
GPQA
GPT-5.5
62.5
OpenAI o1
78.0
MATH
GPT-5.5
89.1
OpenAI o1
94.8
HumanEval
GPT-5.5
93.0
OpenAI o1
92.4
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
OpenAI o1
Strengths
- Tops MATH and GPQA leaderboards
- Self-checks its work
Weaknesses
- Very slow
- Very expensive
- Overkill for simple tasks
Best for
- Research problems
- Olympiad-level math
- Algorithm design
Quick verdict
- Pick GPT-5.5 if you want it smarter, faster, cheaper and longer context.
Auto-generated from the spec sheet. Always validate on your own evals.
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