How to use it
- Take the Print weight from your slicer, and type the Spool price and Spool weight of the filament you buy.
- Type the Printer power while printing and the Print time, then the Electricity price per kWh from your bill.
- Optionally type the Printer price, the Printer life in hours and a Failure margin for failed prints.
- Read the Total cost of the print, then open Working, step by step to see each part.
How the cost is built
A printed part costs the filament it uses, the electricity the printer draws while it runs, and the wear of the machine. The failure margin covers the prints that go wrong, which use material and power without making a usable part.
Filament: grams ÷ spool weight × spool price
Energy: watts ÷ 1000 × hours (kWh)
Electricity: kWh × tariff
Wear: hours × printer price ÷ printer life (hours)
Margin: (filament + electricity + wear) × margin %
Total: subtotal + margin- A kilowatt-hour is 3.6 megajoules, the energy of one kilowatt for one hour. A 120 W printer therefore uses 0.12 kWh in every hour.
- The power is an average while printing. A printer that heats its bed draws more during warm-up, and this simple figure does not show that.
What the calculator does not cover
- Your own time: setup, removing the print, post-processing, packing and delivery.
- Other consumables such as the nozzle, the build plate or glue, unless you include them in the wear or the margin.
- Filament used for supports and purge towers beyond what the slicer reports. Check whether the slicer's weight already includes them.
Worked example: 45 g of filament, a 3-hour print
Filament: 45 g ÷ 1000 g × $20 = $0.90 for a 1 kg spool at $20.
Electricity: 120 W ÷ 1000 × 3 h = 0.36 kWh, and 0.36 kWh × $0.15 = $0.05.
Wear: 3 h × $300 ÷ 2000 h = $0.45. The subtotal is $1.40, and a 5 % failure margin adds $0.07, so the total is $1.47.
Frequently asked questions
Why is the spool weight in grams?
The print weight from the slicer is in grams, so the spool weight has to be in grams too. A 1 kg spool is 1000 g, and a 750 g spool is 750 g.
Where do I find the power of my printer?
The maker's specification gives a rated power, which is usually a maximum. For a realistic cost, use the average while printing, which is lower. A plug energy meter shows that average directly.
What is a failure margin, and which value should I use?
It is an allowance for prints that fail, so the filament and power they waste are included in the cost. The right value depends on your printer and your experience. Choose it from your own record of failed prints.
Why are the printer price and life optional?
Wear turns the printer's price into a cost per hour of printing. It matters for a printer bought for the work, but many people count only the filament and the electricity.
Should the electricity price include the fixed charges on my bill?
No. Enter the price per kWh of the energy you use. Fixed charges do not depend on the printing hours, so leave them out unless you want to allocate a share of them to the prints yourself.
Sources
- Wikipedia: Fused filament fabrication (filament fed from a spool)
- Wikipedia: Kilowatt-hour (1 kWh = 3.6 MJ)
Figures and text last checked on Tuesday, November 10, 2026.