Embodiments relate generally to systems and methods for calibrating a gas detector. Some embodiments may include a gas detector comprising one or more sensing elements operable to detect volatile organic compounds (VOC), and a probe operable to provide air flow into the gas detector, wherein the probe comprises: a housing operable to attach to a main body of the gas detector and operable to hold a calibration tube during calibration of the gas detector; a cap operable to attach to the housing and operable to fit over and cover the calibration tube; and one or more inlets, wherein when a calibration tube is inserted into the probe, the air flows through the calibration tube. In some embodiments of the gas detector, the calibration tube inserted into the probe comprises activated carbon fiber (ACF) filter material.