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deepseek vs chatgpt · updated october 2026

DeepSeek vs ChatGPT: V4 Pro vs GPT-6.1 (2026)

DeepSeek V4.1 Flash and V4 Pro against OpenAI's GPT-6 family

DeepSeek's appeal is simple: strong reasoning, especially on maths and logic, for very little per message. ChatGPT's is breadth: it reads images and files, writes well across every register and has a heavyweight in GPT-6 Astra when things get hard. On LazySusan, DeepSeek comes as V4.1 Flash (fast and efficient) and V4 Pro (deep thinking).

at a glance

DeepSeek and ChatGPT side by side
AttributeDeepSeekChatGPT
MakerDeepSeekOpenAI
Versions on LazySusanDeepSeek V4.1 Flash, DeepSeek V4 ProGPT-6.1 Sol, GPT-6 Astra, GPT-6 Luna, GPT-5.5
Best atLow-cost reasoning and mathsReasoning, everyday writing, broad tasks
Reads imagesNoYes
Largest prompt on LazySusan128K tokens400K tokens
Typical reply, fast model2 tokens (V4.1 Flash)1 token (Luna)
Typical reply, strongest model7 tokens (V4 Pro)77 tokens (Astra)
In the LazySusan APIYes, both modelsYes, Sol, Astra and Luna

edge by area

Summary of where each option has the edge
AreaEdge
Cost per messageDeepSeek
Maths and step-by-step reasoningTie
Images and filesChatGPT
Long inputsChatGPT
WritingChatGPT

Cost per message

DeepSeek V4.1 Flash costs about 2 tokens for a typical reply on LazySusan and V4 Pro about 7 tokens. GPT-6.1 Sol is 16 tokens and Astra 77 tokens. GPT-6 Luna, at about 1 token, is OpenAI's answer for cheap volume.

edge: DeepSeek

Maths and step-by-step reasoning

V4 Pro works through problems methodically and is good value for maths, logic puzzles and code that needs reasoning. GPT-6 Astra is stronger on the hardest problems, at many times the cost.

edge: Tie

Images and files

ChatGPT reads images. DeepSeek on LazySusan is text only, so screenshots, photos and scanned pages need another model.

edge: ChatGPT

Long inputs

DeepSeek accepts prompts up to 128K tokens on LazySusan, and GPT-6 models up to 400K. For long reports or large codebases, ChatGPT has more room.

edge: ChatGPT

Writing

DeepSeek writes clearly but plainly. For copy that needs polish or a particular voice, ChatGPT (or Claude) is the better tool.

edge: ChatGPT

which to pick

Pick DeepSeek or ChatGPT

Pick DeepSeek if…

  • you run a lot of reasoning or maths questions and cost matters
  • your work is text only
  • you want a second opinion on a solution at very low cost
  • your prompts fit within 128K tokens

Pick ChatGPT if…

  • you need to show the model images, screenshots or scans
  • the writing has to be polished
  • you work with long inputs
  • the problem is hard enough to justify GPT-6 Astra

faq

Questions

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