The present invention provides an apparatus for determining a seat belt tension is within a proper range. The apparatus is designed to be easily adapted to existing vehicle safety belt systems. Three points of contact with the safety belt allow the apparatus to be used in portable applications including installing child seats. Generally, two of the contact points support the belt while the third contact point is accomplished using a member responsive to the tension of the seat belt. The response of the member is in communication with a device to indicate the amount of tension present in the seat belt. A visual or audible signal is provided to the operator when sufficient tension has been reached and maintained. The apparatus can be mechanical or electro-mechanical in nature. The apparatus provides the general public with the capability to periodically or continuously monitor the seat belt tension and can be used to secure a child seat alerting the operator when the belt tension is within or outside predefined installation limits.