How many amps does a 3D printer use?

Most desktop filament printers draw about 1 to 3 A from a 120 V outlet. While printing PLA they average 0.7 to 0.9 A, and a 350 W printer peaks at about 2.9 A while its heaters warm up. That is roughly a quarter of what a 15 A household circuit can carry for a long print.

How many amps does a 3D printer use?

A typical desktop 3D printer uses 0.7 to 1.7 A on average at 120 V and up to about 2.9 A at its rated maximum. Bambu Lab rates its A1, P1S and X1 Carbon at 350 W on 110 V, which is 2.9 A at 120 V. The A1 mini tops out at 150 W, or 1.25 A.

Printer	Rated maximum	Peak amps at 120 V	Average on PLA	Average amps at 120 V
Bambu Lab A1 mini	150 W	1.25 A	80 W	0.67 A
Bambu Lab A1	350 W	2.92 A	95 W	0.79 A
Bambu Lab P1S	350 W	2.92 A	105 W	0.88 A
Bambu Lab X1 Carbon	350 W	2.92 A	105 W	0.88 A
Prusa MK4S	240 W supply	2.0 A + supply losses	80 W	0.67 A
Creality K1C	350 W	2.92 A	144 W	1.2 A

Bambu Lab’s maximums come from its spec sheets and the averages from its wiki’s measured test prints. Prusa lists the MK4S at 80 W on PLA and 120 W on ABS, with a 240 W supply. That 240 W is DC output, so the peak wall draw runs a little higher.

Hotter materials raise the average. Bambu Lab measures the A1 at 200 W on ABS, which is 1.7 A, and the X1 Carbon at 150 W, or 1.25 A.

The formula

amps = watts ÷ volts

Peak:     350 W ÷ 120 V = 2.92 A
Printing: 105 W ÷ 120 V = 0.88 A

Bambu Lab’s ratings name 110 V, so at a 110 V outlet the same 350 W is 3.2 A. Use the peak figure to plan a circuit and the average to work out your bill in the electricity cost calculator.

Why a clamp meter reads more

A printer’s power supply can draw more current than watts ÷ volts suggests. Bambu Lab lists the P1S’s power factor while printing at 0.45 to 0.64, and a low power factor raises the current:

amps = watts ÷ (volts × power factor)

140 W ABS average on a P1S: 140 ÷ (120 × 0.45) = 2.6 A

Your bill follows watts, but the wire carries the higher current, and some nameplates list it. MEAN WELL’s LRS-350 datasheet lists a typical input of 6.8 A at 115 VAC at full load for a 350 W supply. When a label gives amps, plan on the label.

Amps on the 24 V side are a different number

Inside the printer, the power supply turns 120 V AC into 24 V DC, and the same watts at a fifth of the voltage means about five times the current. MEAN WELL’s LRS-350-24 delivers up to 14.6 A at 24 V, which is 350.4 W. At the wall, 350 W is only 2.9 A.

Prusa’s 240 W supply is rated 10 A at 24 V, and the MK52 heated bed alone takes 6.25 A of that. These DC amps decide the supply size and the wire gauge inside the printer, not your household circuit. The power supply calculator sizes that side.

What are the electrical requirements for a 3D printer?

A desktop 3D printer needs a grounded 120 V outlet, the standard three-prong NEMA 5-15, on a 15 A or 20 A circuit. Plan on its peak draw, about 2.9 A for a 350 W machine. Everything on that breaker must stay under 12 A, the 80 percent continuous limit, during long prints.

The outlet

Wikipedia’s summary of the National Electrical Manufacturers Association (NEMA) standard calls the 5-15R “the standard 15-ampere electric receptacle (outlet) found in the United States.” It is a hot, neutral and ground device rated 125 V. The printer’s three-prong plug needs that ground pin connected, so skip two-prong adapters. Bambu Lab’s A1, P1S and X1 Carbon accept 100 to 240 V AC at 50 or 60 Hz, so a US outlet needs no converter.

The circuit and how many printers fit

A print over 3 hours is a continuous load under the National Electrical Code (NEC). Under Section 210.20(A), as quoted in IAEI Magazine, the breaker must be at least 125 percent of that load. So the load may use 80 percent of the breaker:

Circuit	Continuous limit	350 W printers that fit
120 V, 15 A	12 A (1,440 W)	4
120 V, 20 A	16 A (1,920 W)	5

Those counts assume nothing else shares the breaker. A bedroom circuit usually feeds several outlets. Add the lamp, the computer and any filament dryer on them. The circuit capacity calculator totals it all against the limit.

When you need 240 V

You need 240 V only for very large heated beds. Modix rates the bed heater on its BIG-60 110 V version at 1,200 W, which is 10 A at 120 V, and puts it on a dedicated 15 A circuit. Beds beyond that outgrow a 120 V circuit. The 240 V outlet guide covers the planning.

Surge protection and UPS

Size a surge protector or uninterruptible power supply (UPS) for the printer’s peak watts, not its average. Some printers ride out an outage without one: Prusa says its MK4 and XL families “can fully recover from a complete loss of power without the need for batteries or a UPS.”