How much we need during retirement will depend on our lifestyle. If we have paid up HDB flat and debt free, we don't need much. We just need money for food, paying bills and insurance.

For a retired couple, they may need to spend on
Food and groceries $1000 pm
Utilities $100 pm
Internet and mobile $100 pm
Medical and insurance $1000 pm
Bus and mrt $100 pm
Holidays and entertainment $100 pm
Miscellaneous $100 pm
Total $2500 pm or $30k pa

So, we don't need much when we retire unless we want to eat at restaurants, go holidays to Europe twice a year, own a big car, go shopping everyday, etc. For this lifestyle you will need $200k pa.