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13:46
Dear @Michael : if you tag my name it'll be easier for me to find out when you leave a message for me here.
I do not know how to answer your question as I never actually lived in HK and I took my PhD elsewhere, not in China. I lived in China while working as a postdoc (i.e. no stipends to pay). However, what I can tell you is: allowing for a large variance based on area & institution, life costs in HK are at least 3x as high as in mainland China.
But mind there's also mainland HK which is considerably cheaper (and messier) than HK island. Also China is a huge country, where Shanghai is way more expensive than anywhere else, followed by Beijing, Shenzhen, etc, down not midtier cities which are quite cost-effective.
General education & civil mentality in HK island is much better than in mainland China, as also international academic reputation, which is something you should add to the balance. However I do not know how hard it would be for a foreigner to fit in, professionally. It is a tough land, but a land of opportunity for sure.
14:43
I feel the cooked food in Beijing is very cheap.
actually I feel its clothes and daily commodities are also very cheap.
 
1 hour later…
15:48
@Captain Try paying for a rent, going out for basic fun and eating out in a decent restaurant in Beijing, while earning a local salary in RMB. It can get fairly cheap, if you're cheap enough to embrace working-class local standards, which is canteen soup for dinner and never going out for fun at night. That's how I fared. Still, it gets way cheaper elsewhere in China, e.g. Guangzhou.
 
7 hours later…
22:31
Dear @Scientist thank you very much for the reply, I was offered joint PhD programme between an institution in HK and china(mainland). The HK stipend is 16,730hkd per month (though I will be paying tuition fee and accommodation fee from it) while the school in china(Shenzhen) offer between 6000-8000rmb per month, That's the reason I asked the question

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