3D printing is an emerging technique in product manufacturing. Its applications have been expanding vastly in homebased production. Compared to traditional manufacturing techniques, such as Computerized Numeric Control (CNC) machine tools, it is believed that 3D printing is more cost effective in fabricating personalized products. The product cost estimation in 3D printing mainly takes material expenditure into account, and extensive studies have been performed for reducing filament expense or development of recyclable filaments. However, electricity expenditure is another inevitable cost in the 3D printing process yet an omitted factor in the cost estimation. To this end, this paper introduces the first in-depth study to understand the energy consumption in 3D printing. Specifically, our study comprises of two parts. The first part quantifies both material and electricity use in the 3D printing, and find that the electricity takes up to 32% of the total cost. The second part characterizes the energy consumption and identifies the sensitivity of various parameters.We also share insights and potential solutions to optimize the power consumption of 3D printers.