Quick Answer
These three phrases all translate to 'according to' or 'based on' in English, but they carry different levels of formality, emphasis, and context. Theo is the most general and versatile, used for opinions, plans, and reports. Dựa theo emphasizes that something is built or reasoned upon a specific source or principle. Căn cứ is the most formal and authoritative, typically referring to laws, official documents, or concrete evidence.
Comparison Table
| Feature | Theo | Dựa theo | Căn cứ |
|---|---|---|---|
| Meaning | According to, following, based on (general) | Based on, relying on, drawing from | Based on (evidence, law, formal ground), due to |
| Formality | General, informal to formal | Slightly more formal than theo, academic | Formal, legal, official, bureaucratic |
| Emphasis | Neutral reference to a source or order | Explicitly highlights the source or foundation used for reasoning/action | Refers to a solid, undeniable basis, rule, or evidence |
| Context | Opinions, plans, instructions, predictions, sequence, general information | Data, research, principles, existing information, analysis, conclusions | Laws, official decrees, regulations, facts, evidence, formal reasons |
| Hán-Việt Connection | Indigenous Vietnamese word | Indigenous 'dựa' (to lean/rely) + 'theo'. Emphasizes the act of relying. | Hán-Việt: Căn (根 - root, basis) + Cứ (據 - evidence, proof). Together: foundation and evidence. |
| Example |
Theo tôi, trời sẽ mưa. According to me, it will rain. |
Dựa theo báo cáo, doanh số tăng. Based on the report, sales increased. |
Căn cứ vào luật, hành vi đó là sai. Based on the law, that behavior is wrong. |
Detailed Explanation
Theo
Theo is the most common and flexible of the three. It can be used in a wide variety of contexts to mean 'according to', 'following', 'in accordance with', or 'based on' in a general sense.
It can introduce a person's opinion or belief: Theo tôi... (According to me...).It can refer to instructions, plans, or orders: Theo kế hoạch (According to the plan), Theo lệnh của sếp (Following the boss's orders).It can introduce general information or reports: Theo tin tức (According to the news), Theo dự báo (According to the forecast).It can also mean 'following' in a physical sense: Anh ấy đi theo tôi (He walked after me).
While theo can imply 'based on', it doesn't emphasize the process of derivation as strongly as dựa theo or căn cứ.
Dựa theo
Dựa theo explicitly highlights that something is 'based on', 'relying on', or 'derived from' a specific source, principle, or set of data. It implies a process of analysis, consideration, or formulation that uses the source as its foundation.
It is frequently used with reports, studies, data, analyses, and principles: Dựa theo số liệu thống kê (Based on statistical data), Dựa theo nguyên tắc này (Based on this principle).It's common in academic or professional contexts where you need to state the foundation of your argument or conclusion.The word dựa itself means 'to lean on' or 'to rely on', so dựa theo literally suggests 'leaning on something and following it'.
Căn cứ
Căn cứ is the most formal and authoritative. It translates to 'based on' in the sense of a strong, legitimate, or official foundation, evidence, or legal ground. It is often used in legal, governmental, academic, or highly formal business contexts where precision and authority are paramount.
It is typically followed by vào or trên (e.g., căn cứ vào luật, căn cứ trên bằng chứng).It refers to laws, regulations, official documents, decrees, concrete facts, or irrefutable evidence: Căn cứ vào Hiến pháp (Based on the Constitution), Căn cứ trên chứng cứ (Based on the evidence).The Hán-Việt origin of căn (root, basis) and cứ (evidence, proof) perfectly conveys its meaning of a solid, foundational basis.
Example Pairs
1A. Theo tôi, ý tưởng này rất hay.
According to me, this idea is very good.
1B. Dựa theo phân tích của chuyên gia, ý tưởng này có tiềm năng.
Based on the expert's analysis, this idea has potential.
2A. Theo quy định của công ty, bạn phải mặc đồng phục.
According to company regulations, you must wear a uniform.
2B. Căn cứ vào quy định mới, tất cả nhân viên phải tiêm vắc xin.
Based on the new regulation, all employees must be vaccinated.
3A. Theo như tôi biết, anh ấy đã đi công tác rồi.
According to what I know, he has already gone on a business trip.
3B. Dựa theo thông tin chính thức, chuyến bay đã bị hoãn.
Based on the official information, the flight has been delayed.
4A. Chúng ta sẽ làm việc theo kế hoạch đã đề ra.
We will work according to the plan that has been set out.
4B. Quyết định được đưa ra dựa theo kết quả khảo sát thị trường.
The decision was made based on the results of the market survey.
5A. Theo dự báo thời tiết, ngày mai trời nắng.
According to the weather forecast, it will be sunny tomorrow.
5B. Dựa theo dữ liệu khí tượng lịch sử, đây là một dự báo hợp lý.
Based on historical meteorological data, this is a reasonable forecast.
6A. Bộ phim này được làm theo một câu chuyện có thật.
This film was made according to a true story.
6B. Bộ phim này được xây dựng dựa trên một câu chuyện có thật.
This film was built based on a true story.
7A. Theo lời khuyên của bác sĩ, tôi nên nghỉ ngơi.
According to the doctor's advice, I should rest.
7B. Dựa theo kết quả xét nghiệm, bác sĩ đã đưa ra chẩn đoán.
Based on the test results, the doctor made a diagnosis.
8A. Anh ấy luôn hành động theo trái tim mình.
He always acts according to his heart.
8B. Căn cứ vào Hiệp định thương mại, chúng ta có thể xuất khẩu sản phẩm này.
Based on the Trade Agreement, we can export this product.
Common Patterns
Theo như + clause: 'According to what...', often used for reported information or what one knows. E.g.,
Theo như tôi hiểu, cuộc họp đã bị hoãn.
According to what I understand, the meeting has been postponed.
Dựa trên / Dựa vào: Often interchangeable with dựa theo, especially when referring to a solid foundation or evidence. Dựa trên can feel slightly more formal or academic than dựa theo. E.g.,
Quyết định này dựa trên bằng chứng khoa học.
This decision is based on scientific evidence.
Chúng tôi dựa vào kinh nghiệm để giải quyết vấn đề.
We rely on experience to solve the problem.
Căn cứ vào / Căn cứ trên: These prepositions are almost always used with căn cứ to specify the foundation. E.g.,
Căn cứ vào Điều 10 của luật, bị cáo bị kết án.
Based on Article 10 of the law, the defendant was sentenced.
Theo dõi: A verb meaning 'to follow', 'to monitor', 'to track'. This is a direct verb derived from theo. E.g.,
Chúng tôi theo dõi sát sao tình hình thị trường.
We closely monitor the market situation.
Common Mistakes
Mistake 1 — Using căn cứ for casual opinions
Using căn cứ for a personal, informal opinion makes it sound overly formal, serious, or even pretentious, as if your opinion is a binding legal decree.
❌ Căn cứ tôi, món ăn này không ngon.
✅ Theo tôi, món ăn này không ngon.
Why it's wrong and how to fix it: Căn cứ requires a formal, evidence-based source, not a simple personal opinion. Use theo for general opinions.
Mistake 2 — Using theo when a clear foundation is emphasized
While theo can sometimes imply 'based on', it doesn't always convey the strong sense of derivation or reliance that dựa theo or căn cứ do. When you want to explicitly state that something is built upon a specific source or data, theo can be too vague.
❌ Quyết định này theo nghiên cứu mới nhất.
✅ Quyết định này dựa theo nghiên cứu mới nhất.
Why it's wrong and how to fix it: Theo here could just mean 'following' the research in a sequence. Dựa theo clearly establishes the research as the foundation upon which the decision was made.
Mistake 3 — Using dựa theo for physical following
Dựa theo is exclusively used for abstract concepts, data, or principles. It cannot be used to describe physical movement or literally following someone or something.
❌ Anh ấy đi dựa theo tôi đến cửa hàng.
✅ Anh ấy đi theo tôi đến cửa hàng.
Why it's wrong and how to fix it: Dựa theo implies 'based on' an abstract source, not physical movement. For physical following, always use theo.
Mistake 4 — Omitting vào/trên with căn cứ
While not always strictly mandatory in very specific contexts, căn cứ almost always pairs with vào or trên to specify its foundation, especially in formal writing. Omitting it can sound incomplete or slightly unnatural.
❌ Căn cứ báo cáo, dự án đã bị đình chỉ.
✅ Căn cứ vào báo cáo, dự án đã bị đình chỉ.
Why it's wrong and how to fix it: Adding vào or trên after căn cứ makes the sentence grammatically complete and naturally flowing in formal Vietnamese, clearly linking the action to its official basis.
Quick Quiz
Fill in the blank with theo or dựa theo:
- _____ dự báo thời tiết, ngày mai trời nắng.
Hint: This is general information from a common source.
Correct answer: Theo
Theo dự báo thời tiết, ngày mai trời nắng.
Explanation: Theo is used for general information, predictions, or reports without emphasizing the analytical process.
Fill in the blank with dựa theo or căn cứ:
- Mức phạt sẽ được áp dụng _____ điều 5 của bộ luật.
Hint: This refers to a specific legal article and implies a formal, authoritative basis.
Correct answer: căn cứ
Mức phạt sẽ được áp dụng căn cứ vào điều 5 của bộ luật.
Explanation: Căn cứ is the appropriate choice for referring to laws, regulations, and official articles due to its formal and authoritative nature.
Fill in the blank with theo or dựa theo:
- Chúng tôi sẽ hành động _____ lời khuyên của chuyên gia.
Hint: This implies making decisions or taking action by relying on an expert's advice.
Correct answer: dựa theo
Chúng tôi sẽ hành động dựa theo lời khuyên của chuyên gia.
Explanation: While theo is possible, dựa theo emphasizes that the action is built upon and relies on the expert's advice as a foundation, making it a stronger choice here.