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AI Models · Compare

GPT-5.5 vs DeepSeek R1

Side-by-side intelligence, speed, price, benchmarks, strengths and weaknesses for GPT-5.5 and DeepSeek R1 — refreshed monthly.

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OpenAI

GPT-5.5

ProprietaryMar 2026

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

Open docs
DeepSeek

DeepSeek R1

Open sourceJan 2025

Open-weights reasoning model that matches o1 at 1/25 the price.

Open docs

Head to head

Spec
GPT-5.5
DeepSeek R1
Intelligence index↑ better
Winner82
73
Speed↑ better
Winner95 tok/s
60 tok/s
Time to first token↓ better
Winner0.42 s
1.5 s
Context window↑ better
Winner400k
128k
Max output↑ better
16k
Winner33k
Input price↓ better
$5.00 / 1M tokens
Winner$0.55 / 1M tokens
Output price↓ better
$15.00 / 1M tokens
Winner$2.19 / 1M tokens
Blended price↓ better
$7.50 / 1M tokens
Winner$0.96 / 1M tokens
License
Proprietary
Open source
Input modalities
text, image
text
Output modalities
text
text

Benchmark showdown

MMLU
GPT-5.5
90.2
DeepSeek R1
87.1
MMLU Pro
GPT-5.5
78.0
DeepSeek R1
75.9
GPQA
GPT-5.5
62.5
DeepSeek R1
71.5
MATH
GPT-5.5
89.1
DeepSeek R1
90.2
HumanEval
GPT-5.5
93.0
DeepSeek R1
91.0

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
DeepSeek R1
Strengths
  • Reasoning at GPT-class scores
  • Open weights
  • Cheap
Weaknesses
  • Slower than non-reasoning peers
Best for
  • Self-hosted reasoning
  • Math & code
  • Cost-sensitive agents

Quick verdict

  • Pick GPT-5.5 if you want it smarter, faster and longer context.
  • Pick DeepSeek R1 if you want it cheaper.

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

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