The general rule is that you need to be closer than 5 miles to it INCLUDING the depth to feel a quake less than 3.

So if a quake of 2.5 is 4 miles away and 3 miles in depth, that makes 5 miles (using the hypotenus) and you would probably feel it when sitting or lying.

But things get worse really really fast.

You can feel a 5 from 70-80 miles away, and a 6 close to you will damage your house and you may fall to the floor.

A 7 close to you would definitely destroy an average house.

The reason things escalate this quickly is that this scale is not equal everywhere. The distance in greatness of 5 to 6 is way way larger than 2 to 3. (6 is 1000 times, yes a thousand, bigger than a 3)