Many Internet of Things (IoT) applications benefit greatly from low-power long-range connectivity. A promising technology to achieve the low-power and long-range requirements is seen in LoRaWAN, a media access control (MAC) protocol maintained by the LoRa Alliance and leveraging Semtech’s patented LoRa radio modulation technology. LoRaWAN provides three different device classes (A, B and C), which provide a tradeoff between performance (i.e., throughput and latency) and energy consumption. This paper offers a theoretical and experimental comparison of these classes. The objective of the quantitative experiment was twofold: to verify the published current levels of different operating modes in a LoRa chip’s datasheet and to compare the battery lifetime for the LoRa class A and C modes of operation. We used a high-end current sensing circuit to gather the voltage levels and temporal variation with increasing payload sizes and spreading factors. Using the Ohmic Law, the energy drain can be calculated and compared across the different spreading factors (SF) and classes.