3D Printing Filament Cost Calculator
Calculates the true filament cost for any 3D print by accounting for spool price, weight used, and material waste. Use it before starting a print to budget accurately.
About this calculator
The cost of a 3D print is not simply proportional to filament weight — you must also account for failed prints, purge lines, and skirts that create unavoidable waste. The formula used here is: Cost = (filamentWeight × (1 + wastePercentage / 100) × spoolPrice) / spoolWeight. Here, filamentWeight is the grams your slicer estimates for the model, wastePercentage adds a fractional overhead (e.g., 10% waste means multiply weight by 1.10), and the result is scaled by the price-per-gram derived from spoolPrice / spoolWeight. For example, a 1 kg spool costing $25 has a unit cost of $0.025/g. Adding waste before dividing ensures you never underestimate your material budget, which is especially important when printing expensive filaments like carbon-fiber composites or flexible TPU.
How to use
Suppose your slicer reports 45 g of filament needed, you have a 1000 g spool that cost $22, and you estimate 8% waste. Plug in: filamentWeight = 45, spoolWeight = 1000, spoolPrice = 22, wastePercentage = 8. Cost = (45 × (1 + 8/100) × 22) / 1000 = (45 × 1.08 × 22) / 1000 = (1069.2) / 1000 = $1.07. So this print costs roughly $1.07 in filament, not counting electricity or machine wear.
Frequently asked questions
How do I find out how many grams my 3D print needs?
Your slicer software (PrusaSlicer, Cura, Bambu Studio, etc.) reports the estimated filament weight in grams after slicing the model. This figure is shown in the print summary before you start. It accounts for your chosen infill percentage, wall count, and support structures, so always re-slice if you change those settings. Use that number directly as your 'Filament Weight Needed' input.
What waste percentage should I use for 3D printing filament cost calculations?
A safe default for experienced users is 5–10%. This covers purge lines, skirts, brims, and the small amount of filament used during heat-up. If you are dialing in a new filament or frequently experience first-layer failures, bump it to 15–20% to avoid surprises. For well-calibrated printers running production batches of proven models, 3–5% is realistic. Multi-color prints with tool changes can generate significantly more waste and may need 20%+ depending on the number of color swaps.
Why does filament cost per gram matter more than cost per spool?
Most prints use a small fraction of a spool, so the per-gram cost lets you compare filaments fairly regardless of spool size (500 g, 1 kg, 2 kg). A $15 500 g spool costs $0.030/g, while a $22 1 kg spool costs $0.022/g — the larger spool is cheaper per gram even though it costs more upfront. Understanding per-gram cost also helps when running multiple materials on one printer, since you can immediately see which material adds the most cost to a given part.