Usage note
大约用来表示大概的时间或数量，比如一天大约走10公里。
dàyuē láiyòng bǎoshí gāngài de shíjiàn huòshù, rúkě yītiān dàyuē zǒu 10 lǐjùmǔ.
大约 is used to indicate approximate time or quantity, for example, one day approximately walks 10 kilometers.
Context note
大约常用于描述不确定的时间或数量，比如天气预报说今天温度大约在25度左右。
dàyuē cháng yòng yú miáo shì bù jìnuò de shíjiàn huòshù, rúkě tāiqí fēngyù shuō jīntiān wēndù dàyuē zài 25 dù yóuzhǐ.
大约 is often used to describe uncertain time or quantity, for example, the weather forecast says today's temperature is approximately around 25 degrees.
5 examples
我每天大约走30分钟。
wǒ měi tiān dà yuē zǒu 3 0 fēn zhōng。
I walk about 30 minutes every day.
这本书大约有100页。
zhè běn shū dà yuē yǒu 1 0 0 yè。
This book has approximately 100 pages.
他每天大约睡8小时。
tā měi tiān dà yuē shuì 8 xiǎo shí。
He sleeps about 8 hours every day.
这趟旅程大约需要3天。
zhè tàng lǚ chéng dà yuē xū yào 3 tiān。
This trip will take approximately 3 days.
这个项目大约花费了10万元。
zhè ge xiàng mù dà yuē huā fèi le 1 0 wàn yuán。
The project cost about 100,000 yuan.
5 mini stories
妈妈说今天天气大约25度，我们去公园玩吧。
mā ma shuō jīn tiān tiān qì dà yuē 2 5 dù， wǒ men qù gōng yuán wán ba。
Mom says today's temperature is approximately 25 degrees, let's go to the park.
爸爸每天大约走10公里，他很健康。
bà ba měi tiān dà yuē zǒu 1 0 gōng lǐ， tā hěn jiàn kāng。
Dad walks about 10 kilometers every day and he is very healthy.
我们计划这个周末去爬山，大约需要3个小时。
wǒ men jì huà zhè ge zhōu mò qù pá shān， dà yuē xū yào 3 gè xiǎo shí。
We plan to go hiking this weekend, it will take approximately 3 hours.
这本书大约有100页，我今天读了20页。
zhè běn shū dà yuē yǒu 1 0 0 yè， wǒ jīn tiān dú le 2 0 yè。
This book has approximately 100 pages, I read 20 pages today.
这个项目大约花费了10万元，我们节省了一些钱。
zhè ge xiàng mù dà yuē huā fèi le 1 0 wàn yuán， wǒ men jié shěng le yì xiē qián。
The project cost about 100,000 yuan, we saved some money.
Mini dialogue
大约几点？
A
我们大约几点见面？
Wǒmen dàyuē jǐ diǎn jiànmiàn?
Approximately what time will we meet?
B
大约下午三点吧。
Dàyuē xiàwǔ sān diǎn ba.
Around three in the afternoon.
大约多远？
A
从这里到公园大约多远？
Cóng zhèlǐ dào gōngyuán dàyuē duō yuǎn?
Approximately how far is it from here to the park?
B
大约要走十分钟。
Dàyuē yào zǒu shí fēnzhōng.
It takes about ten minutes to walk.
Related words and contrasts
similar
大概
dà gài
probably; roughly
Both mean 'approximately'. 大约 is more for numbers.
similar
左右
zuǒ yòu
about; around
Placed after a number, e.g., 三点左右 (around 3 o'clock).
opposite
准确
zhǔn què
exact; accurate
The opposite of an approximate amount.