What 3D printing really costs in electricity
How much power a desktop 3D printer draws, why the heated bed dominates, and how to turn watts and hours into an honest cost per print.
The formula behind the number
Electricity is billed in kilowatt-hours, and a kilowatt-hour is one thousand watts drawn for one hour. To find a print's energy you divide the printer's average watts by 1000 to get kilowatts, then multiply by the hours it runs. Multiplying that energy by your rate per kWh gives the cost. A 150 W printer running ten hours pulls 1.5 kWh, and at fifteen cents per kWh that is about twenty-three cents. The math is small, but it stacks up fast across dozens of prints a month.
Why average watts, not the label
Printer power is not steady. When a print starts, the bed and hotend heaters run flat out and the machine may briefly pull its full rated wattage. Once everything reaches temperature the heaters only cycle to hold it, so the average draw settles far lower than that opening spike. Entering the peak rating would badly overstate the bill. The realistic input is the average across the whole job, which is exactly what a plug-in energy meter reports after a print finishes.
The heated bed is the main cost
On most desktop machines the heated bed is the single biggest continuous consumer of power. A large bed held at 60 C for PLA sips energy, but pushing it to 100 C or more for ABS and PETG raises the average watts noticeably and keeps them high for the length of the print. Bigger beds cost more to heat than small ones, and an open frame loses heat faster than an enclosure, forcing the heaters to work harder. If you want to trim energy use, the bed is the first place to look.
Putting electricity in context
For a single hobby print the electricity is usually a rounding error next to the cost of the filament or resin. Its real value shows up at scale: a small print farm running many hours a day, or a business pricing parts, needs the energy line to be accurate. Comparing the kWh a job uses against the material it consumes also reveals when a slower, cooler profile actually saves money. Treat this calculator as one input in a full cost picture rather than the whole story.