If it moves more than one inch from side to side or toward the front of the vehicle, it is too loose. To make it tight, put your knee in the child safety seat and push down on it while you tighten and fasten the safety belt. There are many types of safety belts in cars. Frequently, three or more types can be found in the same vehicle. Check to see what types of latch plates and retractors are used in the safety belts where you plan to install child safety seats.
Some safety belts require special attachment hardware to secure child safety seats.
The use of a locking clip may be required. The only way to find out how to safely install a child safety seat using the safety belts in your vehicle is to read the vehicle and child seat manufacturer's owners' manuals. Additionally, it is very important that the safety belt is routed through the correct belt path of the child safety seat. Please review the manufacturer's instructions for this information. Children should be snugly secure in child safety seat harnesses.