I am thinking of adopting a dog (tiny sized) from a shelter.

>>2205259
As a general rule, not much at all. But every dog is different and I've seen some little chihuahuas jogging with their human like fucking pros.

Every dog does need stimulation and exercise though. So do factor in a walk in your day.

>>2205259
Size has nothing to do with exercise needs. What breed is it?

>>2205259
That's not a dog that is a large rat

Size mean nothing. Some of the smallest dogs need a lot of exercise due to their breeds (or their parents breeds) being hunting dogs.

>>2205259
I have an 11kg 38cm high Boston mix.
At 5 years old, he walks approximately 15km and jogs approximately 10km per week in fine weather, and walks about 20km per week in the winter (I live in a cold and snowy part of Canada, he wears a parka because he has very short and fine fur). He also gets one vigorous play session (tugging is his favourite) 6 days a week, and plays with my brother's mid size poodle mix 2 or 3 times a week.
He adjusts well to the slight reduction in the winter, and it all seems to be about the right amount of exercise for him. I got him when he was 2 and he was a bit far, this is the most active he's been since I got him, I've worked him up to it and he loves it.

On average for a dog, you want to provide a half hour of exercise twice a day. But as has been said, it can greatly vary by individual and breed so be sure to inform the shelter about your lifestyle and wants (things like how much grooming you want to handle) so they can fit you with the proper dog.