Depends, most WiFi at home has enough range, usually any device within 100 meters can pick up a signal, the power of the signal degrades when going through the walls of differing density so that you will have black spots in your home.
First thing to try is a router reboot, switch off for a minute, power up and see what happens.
If there is no improvement then move the router to a more central location with the least blockage in the signal path.
If that does not improve, invest in a set of WiFi extenders that plug in to your mains sockets that give WiFi via and Internet extender via your home electrical sockets like the TP Link type of networking hardware.
And another reason for a poor signal is more to do with one of the following...
a) Your Neighbour is using your WiFi signal and it is bottlenecking the router.
b) Your Neighbours WiFi signal is on the same channel and causing signal loss, try changing the router channel, suggest you read the vendors site for details on how to reconfigure your network.
c) devices with a high EMF/RF output is interfering with your signal, relocate the router away from this, typical sources are TV sets, Satellite & Cable boxes.
So take your pick and good luck.