3D print farm calculator: startup cost, circuits, power and output

The formula

The calculator starts from print hours per month and scales every other line from that number.

startup cost          = printers × price per printer + extra startup costs
print hours / printer = hours per day × utilization × 30.42 days
farm print hours      = printers × print hours per printer
kWh per month         = farm print hours × average watts ÷ 1000
parts per month       = farm print hours ÷ print hours per part
filament per month    = parts per month × grams per part ÷ 1000

Circuits come from peak watts, not average watts, and the 80 percent continuous-load limit:

circuit limit         = 0.8 × breaker amps × volts
printers per circuit  = circuit limit ÷ peak watts per printer, rounded down
circuits needed       = printers ÷ printers per circuit, rounded up

Cost per part adds three lines:

electricity   = average watts ÷ 1000 × hours per part × price per kWh
filament      = grams per part ÷ 1000 × price per kg
depreciation  = startup cost ÷ (printers × write-off hours) × hours per part

In target mode the calculator runs the parts line backward:

printers needed = target parts per month ÷ parts per printer per month, rounded up

Where the defaults come from

• 105 W average, 350 W peak. The Bambu Lab Wiki lists the P1S at 105 W average while printing PLA and 350 W maximum on a 110 V supply (1,000 W on 220 V). The printer menu fills in the wiki’s figures for six Bambu Lab models. For a Prusa MK4S, Prusa lists 80 W on PLA settings and a 240 W power supply, which caps its draw.
• $0.18 per kWh. The U.S. Energy Information Administration reports an average residential price of 18.19 cents per kWh for January through July 2026. The commercial average for the same months is 13.97 cents. Use the rate on your own bill.
• 4,392 write-off hours. Prusa’s costing guide recovers a printer’s price over six months of continuous printing, 4,392 hours. Use a longer figure to spread the cost over the printer’s working life.
• Placeholders. The $500 printer price, $20 per kg filament, 75 percent utilization and the 2.5-hour, 50 g part are examples, not published figures. Replace each with your own figure.

How much does it cost to start a 3D print farm?

Startup cost is the number of printers times the price of each, plus what you buy before the first print: shelving, spare nozzles and hotends, enclosures, a dryer and any new circuits. Eight printers at a placeholder $500 each come to $4,000 before extras. The calculator adds your extras as one figure.

Worked example: eight printers

These are the calculator’s defaults, with $1,500 of extras added to show where they land.

Line	Calculation	Result
Printers	8 × $500	$4,000
Extras	shelving, spares, enclosures	$1,500
Startup cost	$4,000 + $1,500	$5,500
Depreciation per part	$5,500 ÷ (8 × 4,392 h) × 2.5 h	$0.39

Extras also raise the cost of every part through depreciation. With no extras the depreciation line is $0.28 per part, and with $1,500 it is $0.39.

Startup cost leaves out what you pay every month. Filament and electricity for the same farm come to about $1,835 a month, so the first month’s running cost is a third of the startup bill. New circuits are not in the default either. An electrician’s quote for the circuits the calculator asks for belongs in the extras field.

How many 3D printers do you need for a print farm?

Divide the parts you need each month by what one printer makes in a month. One printer running 24 hours a day at 75 percent utilization prints about 548 hours a month, so 2.5-hour parts come out at 219 per printer. A target of 1,000 parts needs 1,000 ÷ 219 = 4.6, rounded up to 5 printers.

Worked example: 1,000 parts a month

Switch “Plan from” to a target number of parts per month and keep the other defaults.

1. Print hours per printer: 24 h × 0.75 × 30.42 days = 547.5 h.
2. Parts per printer: 547.5 ÷ 2.5 = 219.
3. Printers needed: 1,000 ÷ 219 = 4.57, rounded up to 5.
4. Five printers make 1,095 parts, cost $2,500 at $500 each and need 2 circuits on 120 V, 15 A (4 printers and 1).

Utilization moves the answer as much as print time per part does. At 50 percent the same printer makes 146 parts a month and the target needs 7 printers. Track the hours your printers print for a few weeks and enter that share, not the hours the room is open.

A plate with several parts counts as several parts. Eight parts that print together in 6 hours are 0.75 hours per part.

How many 3D printers can run on one circuit?

Divide 80 percent of the circuit’s watts by each printer’s peak watts and round down. A 120 V, 15 A circuit allows 1,440 W for loads that run 3 hours or more. Bambu Lab lists a 350 W maximum for the P1S on 110 V, so four fit on that circuit and five on 20 A.

The 80 percent comes from the National Electrical Code (NEC). A continuous load is one “where the maximum current is expected to continue for 3 hours or more” (NEC Article 100), and NEC 210.20(A) requires the breaker to be at least 125 percent of the continuous load, as quoted in IAEI Magazine. A breaker at 125 percent of the load means the load may use 80 percent of the breaker.

Printers per circuit from Bambu Lab’s maximum power figures (110 V figure on 120 V circuits, 220 V figure on 240 V), nothing else on the breaker:

Printer	Peak 110 V / 220 V	120 V 15 A	120 V 20 A	240 V 15 A	240 V 20 A	240 V 30 A
A1 mini	150 W / 150 W	9	12	19	25	38
A1	350 W / 1,300 W	4	5	2	2	4
P1S, X1 Carbon	350 W / 1,000 W	4	5	2	3	5
P2S	1,000 W / 1,200 W	1	1	2	3	4
H2D	1,250 W / 1,800 W	1	1	1	2	3

A 240 V circuit does not always fit more printers. Bambu Lab lists higher maximum power for several models on 220 V. A P1S fits two on a 240 V 15 A circuit against four on 120 V 15 A. Use the peak figure your printer’s maker gives for the voltage you run it on.

Peak watts are what the breaker sees when beds heat up together. The average is far lower: the P1S averages 105 W against its 350 W peak. Staggering print starts keeps the beds from all heating in the same minutes, but size the circuits for the peak. Adding a circuit or a 240 V outlet is work for a licensed electrician. To check one circuit with a chamber heater or dryer on it as well, use the circuit capacity calculator.

What the farm uses each month

With the defaults, eight printers print 4,380 hours a month.

Line	Calculation	Per month
Electricity	4,380 h × 105 W ÷ 1000 = 459.9 kWh, at $0.18	$82.78
Parts	4,380 h ÷ 2.5 h	1,752
Filament	1,752 × 50 g = 87.6 kg, at $20 per kg	$1,752.00
Running cost	electricity + filament	$1,834.78

Each part costs $1.33 to make: 5 cents of electricity, $1.00 of filament and 28 cents of depreciation. Filament is three quarters of that, so the spool price matters far more than the power rate. The figure leaves out labor, failed prints and standby power between jobs. The print pricing calculator turns a cost per part into a selling price, and the printer payback calculator shows when a printer has paid for itself.