This guide walks through the exact formula behind the 3D Print Cost Calculator, so you can check any print by hand and see where the number comes from.
The Formula
The calculator adds three direct costs, then applies a buffer and a markup:
- Filament = grams used / spool grams x spool price
- Electricity = watts x print hours / 1000 x rate per kWh
- Machine wear = printer price / 2,500 hours x print hours
- Total cost = (filament + electricity + wear) x 1.10. The flat 10% covers failed prints and waste.
- Sell price = total cost x 2 (a 100% markup)
Two assumptions are built in. The 2,500-hour printer lifespan and the 10% buffer are the calculator's own assumptions, not industry standards. Change them to match your experience. The calculator does not include your labour or packaging; add those yourself (see below).
Worked Example
A 150 g print, 5 hours, on a $300 printer. Assumptions: $25 for a 1,000 g spool, 200 W (the calculator default), and $0.15/kWh (the calculator default).
| Line | Math | Cost | |------|------|------| | Filament | 150 / 1000 x $25 | $3.75 | | Electricity | 200 x 5 / 1000 x $0.15 | $0.15 | | Machine wear | $300 / 2500 x 5 | $0.60 | | Subtotal | | $4.50 | | Total with 10% buffer | $4.50 x 1.10 | $4.95 | | Sell price at 2x | $4.95 x 2 | $9.90 |
Filament and wear dominate. Electricity is the smallest line.
More Examples With the Same Formula
Assumptions: $25 per 1,000 g spool, $300 printer, electricity at the EIA July 2026 US residential average of 18.31 cents/kWh (preliminary, EIA Table 5.6.A). Wattages and print times are illustrative.
| Print | Grams / hours / watts | Filament | Electricity | Wear | Total (+10%) | Sell (2x) | |-------|-----------------------|----------|-------------|------|--------------|-----------| | Phone case | 30 g / 4 h / 120 W | $0.75 | $0.09 | $0.48 | $1.45 | $2.90 | | Vase | 120 g / 10 h / 120 W | $3.00 | $0.22 | $1.20 | $4.86 | $9.72 | | Tool holder | 85 g / 6 h / 200 W | $2.13 | $0.22 | $0.72 | $3.37 | $6.74 | | Small cutter | 25 g / 3 h / 120 W | $0.63 | $0.07 | $0.36 | $1.16 | $2.31 |
At 18.31 cents, the tool holder's electricity is 200 x 6 / 1000 x 0.1831 = $0.22.
Costs the Calculator Does Not Include
Add these on top, using your own numbers:
- Your time. Design, slicing, setup and post-processing. If a print needs 20 minutes of hands-on work and you value your time at an hourly rate of $X, add (20 / 60) x X. Choose a rate you are happy to work for; there is no standard figure.
- Packaging and shipping supplies.
- Post-processing materials such as sandpaper, primer or paint.
- Maintenance parts such as nozzles and build surfaces. The wear line is a rough proxy for these, based on printer price.
- Marketplace and payment fees if you sell online. See the Etsy fees guide.
Tips for Reading the Numbers
- Use the real weight your slicer reports, including supports.
- Use your actual spool price per gram, not a list price from a different time of year. Prices change; record the date you bought.
- Measure wattage with a plug-in watt meter rather than relying on the label.
- If your failure rate is not 10%, adjust the buffer.
- If your printer will last more or fewer than 2,500 hours, the wear line scales proportionally.
Markup
The calculator's 2x sell price means a 100% markup over cost, which is a starting point, not a rule. Whether it covers your time, fees and profit depends on your numbers. Compare against what similar items sell for before you settle on a price.
Key Takeaways
- Cost = (filament + electricity + wear) x 1.10; sell price = cost x 2.
- Electricity is usually the smallest direct cost. See 3D printer electricity cost.
- The calculator leaves out labour, packaging and fees, so add them yourself.
- Replace the 2,500-hour lifespan and 10% buffer with your own data when you have it.
Ready to run your own numbers? Try our free 3D Print Cost Calculator.