In Mumbai you’ll find many apartment for rent that have a variation of –
1 RK – 1 room and kitchen for rent in Mala towers, millat nagar, oshiwara, andheri west
1 BHK – 1 bedroom, hall and kitchen for rent in Mala towers, millat nagar, oshiwara, andheri west
2 BHK – 2 bedrooms, hall and kitchen for rent Mala towers, millat nagar, oshiwara, andheri west
3 BHK – 3 bedrooms, hall and kitchen for rent in Mala towers, millat nagar, oshiwara, andheri west
4 BHk - 4 bedroom, hall and kitchen for rent in Mala towers, millat nagar, oshiwara, andheri west
Villas - Independent Houses for rent in Mala towers, millat nagar, oshiwara, andheri west
If you are living alone, then a 1RK and 1BHK make the most sense. If you need space for an office at home, then you can even go for a 2BHK.
For those with families, a 2BHK or more is better, depending on the number of people in your family.
Nowadays, most builders have a 2.5 BHK (2-and-a-half-bedroom apartment) and so on. These half rooms are not as big as a regular bedroom and you can use this as a study/home office/ storage room and so on.