What is DeepSeek r1?
DeepSeek-R1 is DeepSeek's open-weight 'reasoning' model, released January 20, 2025, under the MIT License. Unlike a normal chatbot, it thinks step by step before answering, making it strong at math, coding, and logic. It matched OpenAI's o1 at a fraction of the cost and was trained largely with reinforcement learning instead of expensive human-labeled data.
Why — the first-principles explanation
Most chatbots answer the instant you hit enter — they blurt out the first plausible words. Reasoning models like R1 do something different: they generate a long internal 'chain of thought,' working through the problem in steps, checking themselves, and only then giving a final answer. This dramatically improves accuracy on tasks that need real logic, like a hard math proof or a tricky bug, where the first guess is often wrong.
What made R1 special is how it learned to reason. Instead of paying humans to write thousands of worked examples, DeepSeek used reinforcement learning: the model was rewarded whenever it reached correct answers, and over many rounds it taught itself to reason better — even discovering behaviors like double-checking and backtracking on its own. This is much cheaper than the human-labeled approach and was a key reason R1 could rival far costlier models.
R1 was also released as open weights under the MIT License, so anyone could download it, inspect it, and run it. Combining frontier-level reasoning, radically lower cost, and full openness is what made R1's January 2025 launch a landmark moment — and why it briefly wiped hundreds of billions off US tech-stock values as investors questioned the need for huge AI budgets.
An example that makes it click
Picture two students taking a hard math test. The first writes down whatever answer pops into his head — fast, but often wrong. The second scribbles out her full working in the margin, catches her own mistakes, and then circles a checked answer. The second student is R1: slower, but far more likely to be right.
And here's the twist in how she learned: nobody handed her a solutions manual. She just kept practicing problems, got a gold star only when the final answer was correct, and figured out on her own that showing her work and rechecking led to more stars. That self-taught, reward-driven practice is reinforcement learning.
Key facts
- DeepSeek-R1 was released on January 20, 2025, under the MIT License as open weights.
- It is a reasoning model that produces a visible step-by-step 'chain of thought' before its final answer.
- It was trained largely with reinforcement learning (rewarding correct outcomes) rather than costly human-labeled examples.
- R1 performed comparably to OpenAI's o1 on math, coding, and reasoning benchmarks at far lower cost.
- In the API it is served as 'deepseek-reasoner' (transitioning to deepseek-v4-pro in 2026).
An open-weight Chinese model family that matched frontier quality at low cost.
Affiliate link — we may earn a commission at no cost to you.▶ The 60-second explainer (script)
What is DeepSeek-R1? It's DeepSeek's reasoning model, released in January 2025, and it works differently from a normal chatbot. Instead of blurting out the first answer, R1 thinks step by step — writing out its reasoning, checking itself, and then answering. That makes it really strong at math, coding, and logic puzzles. The clever part is how it learned: instead of paying humans to write thousands of examples, DeepSeek used reinforcement learning, rewarding the model whenever it got the right answer until it taught itself to reason. And R1 was released open-source under an MIT license, so anyone can download and run it. It matched OpenAI's top reasoning model at a fraction of the cost — which is exactly why it shook the AI world and the stock market when it launched.
What authoritative sources say
People also ask
How is R1 different from regular DeepSeek chat?
R1 reasons step by step before answering, which helps on hard math, coding, and logic, while the chat model answers more directly and quickly.
Is DeepSeek-R1 free?
The weights are free under the MIT License to download and self-host; using it via DeepSeek's API is paid but inexpensive.
Is R1 better than OpenAI's o1?
On many math and coding benchmarks it's comparable, and it's far cheaper and open, though o1 has its own ecosystem advantages.
What replaced R1 in 2026?
DeepSeek's 2026 reasoning capability is delivered through the V4 series, with deepseek-v4-pro succeeding the deepseek-reasoner name.