A seat belt tension sensor assembly including magnets oriented to reduce assembly size comprises a pull plate having portions defining a belt loop opening for receiving seat belt webbing and a sensor opening. First and second magnets are coupled to the pull plate on opposite sides of the sensor opening and are oriented with a first pole adjacent the sensor opening and second pole positioned away from the opening toward a side of the sensor assembly. A sensor disposed in the sensor opening is configured to provide an output in response to flux imparted thereto by the magnets. At least one projection extends from the sensor opening of the pull plate generally towards the sensor and is configured to direct magnetic flux from the magnets in a closed-loop path through the sensor. Upon application of tension to the seat belt webbing, the pull plate is configured to move along a first axis of the seat belt tension sensor assembly relative to the sensor. The output of the sensor is indicative of a level of the tension.