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AI Models · Compare

GPT-5.5 vs GPT-4o

Side-by-side intelligence, speed, price, benchmarks, strengths and weaknesses.

OpenAI

GPT-5.5

ProprietaryMar 2026

OpenAI’s 2026 flagship — strongest at reasoning, coding and tool use.

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OpenAI

GPT-4o

ProprietaryMay 2024

OpenAI’s vision-and-voice flagship from 2024 — still a great default.

Open docs

Head to head

Spec
GPT-5.5
GPT-4o
Intelligence index↑ better
Winner82
72
Speed↑ better
95 tok/s
Winner110 tok/s
Time to first token↓ better
0.42 s
Winner0.4 s
Context window↑ better
Winner400k
128k
Max output↑ better
16k
Winner16k
Input price↓ better
$5.00 / 1M tokens
Winner$2.50 / 1M tokens
Output price↓ better
$15.00 / 1M tokens
Winner$10.00 / 1M tokens
Blended price↓ better
$7.50 / 1M tokens
Winner$4.38 / 1M tokens
License
Proprietary
Proprietary
Input modalities
text, image
text, image, audio
Output modalities
text
text, audio

Benchmark showdown

MMLU
GPT-5.5
90.2
GPT-4o
88.7
MMLU Pro
GPT-5.5
78.0
GPT-4o
73.3
GPQA
GPT-5.5
62.5
GPT-4o
53.1
MATH
GPT-5.5
89.1
GPT-4o
76.6
HumanEval
GPT-5.5
93.0
GPT-4o
90.2

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
GPT-4o
Strengths
  • Strong multimodal
  • Voice-native
  • Mature ecosystem
Weaknesses
  • Weaker than GPT-5.5 on reasoning
  • Smaller context vs newer models
Best for
  • General-purpose chat
  • Voice apps
  • Vision tasks

Quick verdict

  • Pick GPT-5.5 if you want it smarter and longer context.
  • Pick GPT-4o if you want it faster and cheaper.

Auto-generated from the spec sheet. Always validate on your own evals.

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