# Giả sử: suppose that in Vietnamese (B2)

> Giả sử sets up a situation to think through, like English "suppose" or "assuming".

Source: https://vietnamesebuddy.com/grammar/gia-su-suppose/ · Updated 2026-10-17

**suppose that**

Pattern: `Giả sử / Giả dụ (rằng) + [sentence] + thì …`

Level: B2 (our estimate) · Register: formal

Typed without accents: gia su

Variants:

- giả dụ (rare)

*Giả sử* sets up a situation to think through, like English "suppose" or "assuming". It opens the sentence, *rằng* (that) may follow, and the consequence comes after a comma or *thì*: *Giả sử các yếu tố khác không đổi, …*, assuming other factors stay the same, …

The difference from *nếu* (if) is the purpose. *Nếu* sets a condition that may well come true: *Nếu mai mưa thì mình ở nhà.* *Giả sử* asks the reader to accept something for the sake of argument, often something unlikely or only imagined, and then follows where it leads. That's why it's at home in papers, in maths and economics, and in reports that work through a scenario step by step.

People also use it when they think aloud: *Giả sử anh trúng số thì anh làm gì?* Suppose you won the lottery, what would you do? When the imagined thing is a worry, Saigon speech prefers *lỡ* (what if): *Lỡ mai mưa thì sao?*

*Giả dụ* is an older variant with the same meaning. It's rare now, so you only need to recognise it. For "assume" as a verb in a paper, writers use *giả định*: *Mô hình giả định rằng …*, the model assumes that …

## Examples

- Giả sử các yếu tố khác không đổi, khi thu nhập tăng thì nhu cầu du lịch cũng tăng. — Assuming other factors stay the same, when income rises, demand for travel rises too.
- Giả sử rằng mỗi hộ tiết kiệm 10% lượng điện, áp lực lên lưới điện sẽ giảm đáng kể. — Suppose every household saved 10% of its electricity: the strain on the grid would ease considerably.
- Giả sử lãi suất giữ nguyên, lợi nhuận năm nay của ngân hàng ước đạt khoảng 2.000 tỷ đồng. — Assuming interest rates hold, the bank's profit this year is estimated at around 2,000 billion đồng.
- Giả sử anh trúng số thì anh làm gì đầu tiên? — Suppose you won the lottery, what's the first thing you'd do?

## Compare

- [If … then: nếu … (thì)](https://vietnamesebuddy.com/grammar/neu-thi-if/): if

Previous in Linking ideas: [So … that: đến nỗi, đến mức](https://vietnamesebuddy.com/grammar/den-noi-so-that/)
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