3D print cost calculator — filament, electricity and time

What this is for: work out the real cost of a single 3D print — material, electricity and an allowance for the prints that failed. You enter the model weight from your slicer or the filament length, the spool price and the rate from your electricity bill. The calculator runs in your browser; nothing is sent to a server.

The price of a spool on its own tells you nothing about what a particular print costs. The same model off the same spool can cost twice as much if you print it with high infill, with supports, and on a printer whose heated bed runs for twelve hours. The calculator below breaks the cost into the three components that can actually be measured: material used, electricity drawn, and a statistical allowance for failed attempts.

How we calculate it — the formula

The calculator rests on three simple operations. They are worth knowing, because they tell you which component is driving your cost up and where it is even worth looking for savings.

Material cost = print weight / filament weight on the spool × spool price. Note: that means the weight of the filament, not of the whole spool including the core. A spool described as 1 kg holds 1000 g of polymer plus several hundred grams of core on top of that.

Energy used = average power in watts × print time in hours / 1000. The result is in kilowatt-hours, the same unit you will find on your bill. Electricity cost = kWh × the PLN/kWh rate.

The allowance for failed prints is charged on the sum of material and electricity, because a failed print wastes both. Total cost = (material + electricity) × (1 + allowance / 100), and cost per hour is the total cost divided by the print time.

If you enter length instead of weight, the calculator first converts it to mass: mass = pi × (diameter / 2)² × length × density. For 1.75 mm filament that works out at roughly 2.98 g per metre at a density of 1.24 g/cm³. Treat the densities as nominal values for the polymer family — Porima does not publish densities in its FDM parameter table, so we use the commonly accepted figures for the polymer here, not a measurement of a specific batch.

A worked example with real numbers

You are printing an enclosure in PLA. The slicer reports 85 g and 6 hours 30 minutes. The spool cost 89 PLN and held 1000 g of filament. A power meter shows the printer draws 120 W on average (that figure is an example — yours may be completely different, more on that below). You pay 1.10 PLN per kWh. From the last three months you know that about 8% of your grams end up in the bin.

• Material: 85 / 1000 × 89 = 7.57 PLN
• Energy: 120 × 6.5 / 1000 = 0.78 kWh, that is 0.78 × 1.10 = 0.86 PLN
• Base subtotal: 8.42 PLN, allowance 8% = 0.67 PLN
• Total cost: 9.10 PLN, that is 1.40 PLN per hour of printer time

The most important conclusion from this example: electricity is about 10% of the cost. People usually estimate far more. The table below shows how that share moves with power draw — for the same 85 g print, 6.5 h and a rate of 1.10 PLN/kWh.

Average power draw	Energy used	Electricity cost	Electricity as a share of cost
60 W	0.39 kWh	0.43 PLN	5.4%
100 W	0.65 kWh	0.72 PLN	8.6%
120 W	0.78 kWh	0.86 PLN	10.2%
200 W	1.30 kWh	1.43 PLN	15.9%
350 W	2.28 kWh	2.50 PLN	24.9%

The table is nothing more than the formula worked through for a fixed material cost of 7.57 PLN. These are not any printer manufacturer's data.

Frequently asked questions

Should I add supports and the purge tower?

You do not need to do it by hand. The weight your slicer reports after slicing covers everything the printer will actually extrude, including supports, skirt and the purge tower on multi-material prints. Enter that value unchanged.

Why does power draw vary so much?

Because it is dominated by the heated bed, not the hotend. A printer with a small bed running PLA at 60 °C will draw completely different power from the same machine running ABS with the bed at 110 °C inside an enclosed chamber. That is why the technical materials in Porima's table — ABS, ASA, PC/ABS or PA with a heated chamber — genuinely push your electricity bill up, even though the filament itself looks much the same.

What is a sensible allowance for failed prints?

There is no single figure that could honestly be quoted here. It depends on what you print and how well tuned your profiles are. Rather than guessing, spend a month weighing your failed prints and waste, then divide that by the total grams consumed. It takes a few minutes a month and gives you a number that genuinely describes your printer.

Does wet filament affect the cost?

Very much so. Moisture does not increase the grams consumed, but it does increase the number of prints you throw away, which pushes the allowance up. It is the cheapest thing to fix in this whole calculation — a dryer and an hour of your time.

Does the calculator data go anywhere?

No. The whole script runs locally in your browser. There is no form submission, no login and no saving of results.

Related tools and pages

• 3D print parameters — official parameters for twenty-five materials — good settings mean fewer prints in the bin.
• How much filament is left on the spool — weigh the spool and check it will last another print before you start costing it.
• Volumetric flow rate calculator — check whether the print speed behind your time estimate is even achievable.
• Drying filament — temperature and time — the simplest way to bring down your allowance for failed prints.
• Wet filament — the most common cause of prints you pay for twice.
• Tangled filament on the spool — it can kill a twelve-hour print in its final hour.
• Warping — with ABS and ASA it is the main reason allowances climb into double figures.
• Print temperature chart — Porima's full official parameters for 25 materials.