How to Calculate Filament Cost for a 3D Print

To calculate filament cost for a 3D print, multiply the grams of filament the print uses by the price per gram, which is the spool price divided by the spool weight. A 120-gram print from a $25, 1-kilogram spool costs $3.00. Price your exact print with our free filament cost calculator.

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The Formula: Grams Times Price per Gram

Filament cost has one formula and two inputs, and both inputs are numbers you already have. The cost of a print equals the grams of filament it uses multiplied by the price per gram, and the price per gram equals the spool price divided by the spool weight in grams. A standard spool holds 1,000 grams and commonly costs $20 to $30, so the price per gram is $0.020 to $0.030, or two to three cents, and a 120-gram print from a $25 spool costs 120 times $0.025, which is $3.00. The formula works for any spool size: a 750-gram spool at $22 costs $0.0293 per gram, and a 250-gram sample spool at $9 costs $0.036 per gram, which is why small spools look cheap on the shelf but cost more per print. The grams figure must include everything the printer extrudes, not just the finished model, because supports, brims, rafts, and purge lines all consume filament, and a slicer estimate that reports only the model weight understates the cost. The honest grams number is the slicer total, including supports, or the weighed spool difference before and after the print, and either one plugged into the formula gives a cost you can defend. Rounding belongs at the end only: keep the price per gram to four decimal places through the multiplication, then round the final cost to cents, because rounding the per-gram price first introduces errors that grow with larger prints.

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Finding the Grams: Slicer Estimates, Weighing, and Density

Three methods give the grams figure, and they agree closely enough that any one of them is fine for pricing. The easiest is the slicer estimate: slicing software reports the filament weight for the print, including supports when that option is on, and that number is usually within a few percent of reality, because slicers compute it from the extrusion path and the filament density they assume. The most accurate is weighing: weigh the spool before the print and after it, and the difference is the grams used, which captures supports, purge, and failed restarts exactly, and a kitchen scale with gram resolution is accurate enough for the job. The fallback is volume times density: the model volume in cubic centimeters multiplied by the filament density, about 1.24 grams per cubic centimeter for PLA, 1.27 for PETG, and 1.04 for ABS, gives the model weight, to which supports must be added separately, which is why this method is a fallback rather than a first choice. Two cautions apply to all three methods: first, moisture changes weight slightly, because damp filament weighs more without printing better, so a spool stored open in a humid room gives a slightly inflated grams figure, and second, the slicer density setting must match the actual filament, because a slicer assuming PLA density for a PETG print misstates the weight by a few percent. For a single print, use the slicer number, and for a print you sell repeatedly, weigh a sample run once and use that measured weight for every copy.

Filament Cost per Gram: PLA, PETG, ABS, and TPU

Material choice moves the cost more than most beginners expect, because specialty filaments cost two to four times as much per gram as basic PLA. Standard PLA at $25 per kilogram costs $0.025 per gram, so a 100-gram PLA print costs $2.50, and PLA is the cheapest common material, which is one reason it dominates hobby printing. PETG at $28 per kilogram costs $0.028 per gram, so the same 100-gram print costs $2.80, a small premium for better weather and temperature resistance. ABS at $26 per kilogram costs $0.026 per gram, nearly the same as PLA, but ABS printing needs an enclosure and ventilation, which are costs of a different kind, covered below. TPU flexible filament at $35 per kilogram costs $0.035 per gram, so the 100-gram print costs $3.50, and specialty filaments climb from there: wood-filled and marble-filled blends run $40 to $50 per kilogram, carbon-fiber blends $50 to $70, and engineering filaments such as nylon and polycarbonate $60 and up, which can push a 100-gram print past $6.00 in material alone. The practical rule is to price the material you actually used, not the cheapest material on the shelf, because a customer quoted a PLA price for a carbon-fiber part will either lose money or renegotiate, and neither outcome is good. Keep a small table of your own spools, with price and weight per spool, and the per-gram column updates itself whenever a spool price changes.

The Costs People Forget: Supports, Failures, and Machine Time

Material is the visible cost, but three forgotten costs quietly eat the margin on a printed part. Supports and brims are the first: a model that weighs 100 grams can easily need 30 grams of supports, which raises the material cost by 30 percent, and supports are pure waste after removal, so the honest grams figure always includes them. Failed prints are the second: a print that fails at 80 percent has consumed 80 percent of its filament for nothing, and over a run of prints, a failure rate of even one in ten adds about 10 percent to the average material cost per successful part, which is why experienced sellers track failures and build them into pricing rather than pretending every print succeeds. Machine time and electricity are the third, smaller than people fear but not zero: a typical desktop printer draws 100 to 200 watts while printing, so a 10-hour print at average electricity prices costs roughly $0.15 to $0.30 in power, which is small next to a $3.00 material cost but real, and the printer itself wears, with nozzles, belts, and build surfaces needing replacement on a schedule. A print that takes hours also ties up the machine, and that opportunity cost matters when orders queue. For a print that ran long, our free minutes to hours converter turns the print duration into decimal hours for a job log, and our free word counter keeps the listing description for the part inside a marketplace limit.

Pricing a Print to Sell: From Material Cost to a Fair Price

A selling price starts from the material cost and adds the other costs in order, because skipping a layer is how sellers lose money politely. Step one is the material cost from the formula above, including supports and a failure allowance, so a $3.00 print with 30 percent supports and a 10 percent failure allowance becomes about $4.30. Step two is machine time, priced either as an hourly rate for the printer, commonly $1 to $3 per hour for a desktop machine, or as a flat setup fee, and a 10-hour print at $1.50 an hour adds $15.00, which is why long prints cost far more than their material suggests. Step three is post-processing, sanding, painting, or assembly, priced at a labor rate for the minutes it takes, because a print that needs an hour of finishing is an hour of work, not a free extra. Step four is the margin, the profit that keeps the operation running, and a common rule is to charge two to three times the total cost for a hobby sale, or to set a minimum order price, such as $10, so that tiny prints are not sold at a loss after fees and packaging. The result for the running example, $4.30 material plus $15.00 machine time plus finishing, lands well above the $3.00 material cost, and that gap surprises beginners but it is the honest price: the material is the cheapest part of a 3D print, and the time is the expensive part. Our guides to calculating a percentage off a sale price and calculating customer acquisition cost cover the pricing and selling math that surrounds the print itself.

Common Mistakes That Break Filament Cost Math

Five mistakes account for most wrong filament costs, and each one is easy to spot once named. First, using the gross spool weight, including the spool itself, instead of the net filament weight, which understates the price per gram and makes every print look cheaper than it is. Second, pricing the model weight only and forgetting supports, brims, and purge lines, which understates the cost by 10 to 40 percent depending on the geometry. Third, ignoring failed prints entirely, which makes a batch look profitable on paper while the scrap bin tells a different story. Fourth, using the cheapest spool price on the market instead of the price actually paid, which matters when a specialty color or brand costs double the budget option. Fifth, forgetting sales tax, shipping, or import fees on the spool, which are part of the spool price for an honest per-gram figure. A final check catches all five: weigh a finished print run, divide the spool cost by the grams actually consumed including waste, and compare that figure with the slicer estimate, because agreement between weighing and slicing means the inputs are right, and disagreement means one of the five mistakes happened. Keep the check as a habit for any print you sell repeatedly, and filament cost becomes a number you can quote with confidence instead of a guess that unravels at the end of the month.