An inhalation device for inhaling a vaporized substance that includes metering capabilities to inform a user when a particular amount of substance has been consumed. The device includes an inlet having an opening, an outlet, a processor, an atomizer configured to vaporize an unvaporized substance into a vaporized substance. The device further includes a channel positioned between the atomizer and the outlet, wherein the vaporized substance flows downstream from the atomizer to the outlet via the channel, a light signal device, wherein the light signal device emits light, and a light sensor, wherein the light sensor senses the light from the light signal device. In addition, the light signal device and the sensor are positioned in the channel such that the vaporized substance can flow past the sensor and the light signal device, the opening is configured to allow entry of air into the device that flows to the atomizer, the inlet is configured such that the air flows at a substantially constant rate, and the processor, using the substantially constant rate and the data from the light sensor, is configured to meter an amount of vapor consumed by a user.