How to use 倍 (bèi) in Chinese grammar: -times, -fold and multiplication
To talk about multiplication and multiples in Mandarin Chinese, you can use 倍 (bèi). This character works very much like “-times” or “-fold” in English, for example in “ten times” or “two fold”. In other words, you can use 倍 to say things like “A is twice as good as B” in everyday conversation.
There are three main ways to use 倍 to talk about multiples and multiplication in Chinese. They use the characters 是 (shì), 有 (yǒu) and 比 (bǐ). Let's go through them one by one.
Using 倍 with 是
The first 倍 structure we'll look at uses 是. The structure is:
[noun] 是 [noun] 的 [number] 倍
You can use this to say “[noun] is [number] times [noun]". Notice how Chinese says the two nouns first, then the number and then 倍. English puts the number with ‘times’ between the two nouns.
Let's have a look at some example sentences for this structure.
中国人口大约是英国人口的二十一倍。
米饭的热量是白菜的数倍。
氧原子的重量几乎是氢原子的十六倍。
日本人口是台湾人口的五倍左右。
我现在的体重是过去的两倍。
For giving straight multiplications of numbers, the structure is usually re-arranged a little bit. It's still basically the same, though. Some examples:
二的四倍是八。
三的三倍是九。
You may also hear 二倍, e.g.:
二的二倍是四。
Note that there is a special way of saying “double”. Instead of 两倍 (which is more versatile), you might also hear people say 双倍. This is to talk about doubling things rather than “two times”. Some examples:
一角硬币的价值是五分的双倍。
你加班我付你双倍工钱。
双倍 is more for very fixed, definite ‘doubling’ of something.
Using 倍 with 有
The second 倍 structure we're looking at uses 有. The structure is very similar to the first one:
[noun] 有 [noun] 的 [number] 倍
This structure is identical to the one above, but 是 is swapped for 有. Whether to use 是 or 有 depends, quite intuitively, on whether something is or has a quality that's a number of times something else. Bear in mind that in most situations the 是 structure is probably the better choice. Let's have a look at some example sentences:
光速有声速的八十八万多倍。
他们国家的物价有我们国家的两倍。
Each of the above sentences could just as well be expressed with 是 instead of 有. Also be prepared for some variations on these structures, such as:
法定假日加班有三倍的工资。
我们的投资数额有好几倍的差距。
The amount we invest differs by several times.* (If anyone can think how to phrase this nicely in English, please share it in the comments!)Using 倍 with 比
The final 倍 structure is very different to the previous two. It uses 比, and its meaning is different in an important way. Let's look at the structure first:
[noun] 比 [noun] [adjective] [number] 倍
It looks very similar to the 是 and 有 structures described above. However, when you use 倍 with 比 like this, the multiplication is one time more.
That means that if you use 一倍 in this structure, you're doubling the amount. If you use 两倍 in this structure, you're tripling the amount.
In other words, rather than just using the number as a multiple as in the 是 and 有 structures, the 比 structure adds that many multiples on to the quantity. That is, when you use the 比 structure, you also include the original quantity.
If you're confused, looking at these example sentences should help. To try and make this clearer, each example is given twice, once with the 是 structure and once with the 比 structure.
蓝箱子比红箱子重一倍。
蓝箱子的重量是红箱子的两倍。
The blue box is twice as heavy as the red box.他们的人数比我们多两倍。
他们的人数是我们的三倍。
There are three times as many of them as us.这个城市的人口比那个城市的多两倍。
这个城市的人口是那个城市的三倍。
This city's population is three times that city's.Remember that you can always use the 是 or 有 structure to keep things clear, as they work the same as in English. The 比 structure is common, though, so it's important to understand it.
