GPT-5.5 vs DeepSeek V4 ProBenchmark Comparison 2026

Objective comparison based on public benchmarks updated weekly: Intelligence Index, GPQA Diamond, Chatbot Arena ELO, pricing and speed.

Overall winner (2026)

GPT-5.5

5 of 7 criteria won

OpenAI

GPT-5.5

Winner

Intelligence Index

60.2

Coding Index

59.1

5 criteria won

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DeepSeek

DeepSeek V4 Pro

Intelligence Index

51.5

Coding Index

47.5

2 criteria won

View full profile

Detailed Comparison

CritérioGPT-5.5DeepSeek V4 Pro
Chatbot Arena ELO
Intelligence Index (AA)60.251.5
Coding Index (AA)59.147.5
GPQA Diamond94.0%91.0%
Input price ($/1M tok)$5.00$0.43
Output price ($/1M tok)$30.00$0.87
Context window1.1M tokens1.0M tokens
Speed (tokens/s)64 tok/s54 tok/s

✓ = winner in this criterion • Source: Artificial Analysis, LMArena, official APIs • Updated weekly

Technical Specifications

GPT-5.5

Company
OpenAI
Context window
1.1M tokens
Input ($/1M tok)
$5.00
Output ($/1M tok)
$30.00
Speed
64 tok/s
Release
Apr 2026
Multimodal
Yes
Open Source
No
Official website
Visit

DeepSeek V4 Pro

Company
DeepSeek
Context window
1.0M tokens
Input ($/1M tok)
$0.43
Output ($/1M tok)
$0.87
Speed
54 tok/s
Release
Apr 2026
Multimodal
No
Open Source
Yes
Official website
Visit

When to use GPT-5.5 vs DeepSeek V4 Pro?

Choosing between GPT-5.5 and DeepSeek V4 Pro depends on your use case, budget and technical requirements. Below, a practical guide based on benchmark data and each model's specifications.

Use GPT-5.5 when:

OpenAI · Multimodal

  • Processing images, PDFs and visual documents alongside text — useful for analyzing contracts, reports with charts and mixed content
  • Long document analysis — 1.1M tokens context window allows processing books, legal databases and extensive logs
  • API integration in SaaS applications — direct API access with documented SLA
View full GPT-5.5 profile

Use DeepSeek V4 Pro when:

DeepSeek · Text · Open Source

  • High-volume token projects — at $0.435/1M input tokens, the cost per call is low enough for production use at scale
  • Self-hosted projects with privacy requirements — ideal for sensitive data that cannot leave your own infrastructure
  • Long document analysis — 1.0M tokens context window allows processing books, legal databases and extensive logs
  • AI agents with tool calling — workflow automation, external API integration and data pipelines
View full DeepSeek V4 Pro profile
SWEN Verdict: GPT-5.5 wins in more objective criteria in this comparison (5 vs 2). For most use cases, GPT-5.5 offers better aggregate performance — but DeepSeek V4 Pro may be preferable if your project prioritizes high-volume token projects.

Frequently Asked Questions

GPT-5.5 or DeepSeek V4 Pro: which is better?

GPT-5.5 wins in 5 of 7 criteria analyzed. Check the full table to choose based on your use case.

Where does this benchmark data come from?

Data is aggregated from Artificial Analysis (Intelligence Index, Coding Index) and Chatbot Arena/LMArena (ELO). Pricing and specs come from official APIs. Updated weekly.

What is the Intelligence Index?

The Intelligence Index is an aggregate score from Artificial Analysis that combines multiple academic benchmarks (MMLU, GPQA, LiveBench, etc.) into a single rating. The higher the score, the more capable the model is at reasoning tasks.

Is GPT-5.5 cheaper than DeepSeek V4 Pro?

No. DeepSeek V4 Pro is cheaper: $0.435/1M input tokens vs $5/1M tokens for GPT-5.5 — a 1049% difference. For high-volume projects, DeepSeek V4 Pro can reduce costs substantially.

GPT-5.5 or DeepSeek V4 Pro: which has a larger context window?

GPT-5.5 has the larger context window: 1.1M tokens vs 1.0M tokens. For long document analysis, extensive transcripts or full codebases, the larger context window is a decisive criterion.

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GPT-5.5 vs DeepSeek V4 Pro: Benchmark Comparison 2026 | SWEN.AI