3D Printing Cost Math: Filament, Electricity, and Wear

Calculating what a 3D print actually costs requires summing three direct inputs—extruded filament mass (m = π × r² × L × ρ), two-phase electrical energy consumption (kWh across preheat and steady-state PID duty cycles), and hourly hardware/consumable depreciation—then multiplying by a print failure factor. While electricity on an unenclosed PLA print rarely exceeds $0.02–$0.03 USD per print hour, ignoring polymer density differences, heated-bed power draw, nozzle wear, and machine amortization routinely understates true part cost by 30% to 45%.

The Complete 3D Print Cost Equation

Slicers display an estimated filament weight and print duration, tempting users to treat spool price per gram as the entire cost of a part. For accurate workshop accounting or small-batch quoting, total cost per delivered part (C_total) is:

C_total = (C_filament + C_electricity + C_hardware) × (1 + f_fail)

Where:

• C_filament is material cost derived from extruded filament length, cross-sectional area, polymer density, and spool price per gram,
• C_electricity is electrical energy consumed during bed/hotend preheating plus steady-state printing (and filament drying, if active), multiplied by your local utility tariff ($/kWh),
• C_hardware is print duration (hours) multiplied by hourly printer depreciation and consumable wear (nozzles, PEI build sheets, lubricants), and
• f_fail is the scrap and reprint margin (typically 0.05 for dialed-in PLA/PETG or 0.10–0.15 for tall technical ASA/nylon parts).

Deriving Filament Volume and Mass from Length and Density

G-code commands (G1 E...) meter linear millimeters of solid filament (L), not mass. Because solid filament is a cylinder of diameter d (radius r = d / 2), its cross-sectional area A, volume V, and mass m for a polymer of solid density ρ (g/cm³) are:

A = π × r² = π × (d / 2)²
V = A × L = π × r² × L
m = V × ρ = π × r² × L × ρ

To keep units consistent when converting millimeters to grams (g/cm³, where 1 cm³ = 1,000 mm³), divide volume in mm³ by 1,000:

• Standard 1.75 mm filament (r = 0.875 mm = 0.0875 cm): A = π × (0.875 mm)² = 2.40528 mm² = 0.0240528 cm². Every 1.00 m (1,000 mm) of 1.75 mm filament occupies 2.4053 cm³ (2,405.3 mm³).
• 2.85 mm filament (r = 1.425 mm = 0.1425 cm): A = π × (1.425 mm)² = 6.37940 mm² = 0.0637940 cm². Every 1.00 m (1,000 mm) of 2.85 mm filament occupies 6.3794 cm³ (6,379.4 mm³).

Worked Example: 40.00 m Print Job in 1.75 mm PLA vs PETG (and ASA)

Suppose a slicer reports that a functional bracket plus supports and purge line consumes L = 40.00 m (40,000 mm / 131.2 ft) of 1.75 mm filament. Total extruded plastic volume is:

V = 2.40528 mm² × 40,000 mm = 96,211.3 mm³ = 96.2113 cm³

Applying m = V × ρ across standard polymer densities (see PLA vs PETG vs ASA: Mechanical and Thermal Trade-Offs):

1. PLA (ρ = 1.24 g/cm³, Prusament PLA): m_PLA = 96.2113 cm³ × 1.24 g/cm³ = 119.30 g (4.21 oz). At $22.00 per 1,000 g ($0.022/g), C_filament = 119.30 g × $0.022/g = $2.62.
2. PETG (ρ = 1.27 g/cm³, Prusament PETG): m_PETG = 96.2113 cm³ × 1.27 g/cm³ = 122.19 g (4.31 oz). Because PETG is 2.42% denser than PLA, the exact same 40.00 m G-code consumes 2.89 g more plastic by weight. At $22.00/kg, C_filament = 122.19 g × $0.022/g = $2.69.
3. ASA (ρ = 1.07 g/cm³): m_ASA = 96.2113 cm³ × 1.07 g/cm³ = 102.95 g (3.63 oz). Because ASA is less dense than PLA or PETG, a 1,000 g (1 kg) spool of ASA yields 388.6 m of 1.75 mm filament—15.9% more length (and printed volume) than a 1 kg spool of PLA (335.3 m) and 18.7% more than a 1 kg spool of PETG (327.4 m).

Polymer Material (1.75 mm)	Density ρ (g/cm³)	Volume per 1 kg Spool	Length per 1 kg Spool (m / ft)	Mass per Meter
PA12 (Nylon)	1.02	980.39 cm³	407.6 m (1,337 ft)	2.45 g/m
ABS	1.04	961.54 cm³	399.8 m (1,312 ft)	2.50 g/m
ASA	1.07	934.58 cm³	388.6 m (1,275 ft)	2.57 g/m
PC (Polycarbonate Blend)	1.20	833.33 cm³	346.5 m (1,137 ft)	2.89 g/m
TPU 95A	1.21	826.45 cm³	343.6 m (1,127 ft)	2.91 g/m
PLA	1.24	806.45 cm³	335.3 m (1,100 ft)	2.98 g/m
PETG	1.27	787.40 cm³	327.4 m (1,074 ft)	3.05 g/m
PETG-CF (Carbon Fiber)	1.29	775.19 cm³	322.3 m (1,057 ft)	3.10 g/m

You can relate total print volume (96,211.3 mm³) directly to extrusion rates (mm³/s) in the Extrusion Flow, Volumetric Speed & E-Steps Calculator and Max Volumetric Speed Explained.

Heated-Bed and Hotend Electricity Math: Peak Watts vs Duty Cycle

Multiplying a printer’s power supply unit (PSU) nameplate rating (250–500 W) by print hours wildly overestimates electricity cost. A PSU rating indicates peak capacity, whereas actual consumption splits into two thermal phases:

1. Preheat phase (t_preheat, typically 0.08–0.15 hours / 5–9 minutes): Both the heated bed (150–250 W) and hotend cartridge (40–60 W) run near 100% duty cycle (P_preheat ≈ 240–320 W) to bring thermal mass from room temperature (~22 °C) to setpoint.
2. Steady-state printing phase (t_steady): Once at temperature, PID controllers pulse the heaters at 20%–45% duty cycle solely to balance convective and radiative heat loss (Q_loss ∝ T_bed − T_ambient), while steppers, fans, and logic boards draw a constant 25–40 W.

Because bed surface area is dozens of times larger than the insulated hotend block, heated-bed temperature dominates steady-state power draw. Measurements published in the Prusa Knowledge Base FAQ report an average steady-state consumption on an MK-series printer at 26 °C (79 °F) room temperature of 80 W (0.080 kW) for PLA (60 °C bed) and 120 W (0.120 kW) for ABS/ASA (100–110 °C bed).

Total electrical energy (E_kWh) and electricity cost (C_electricity) are:

E_kWh = (P_preheat_W × t_preheat_h + P_steady_W × t_steady_h) / 1,000
C_electricity = E_kWh × R_tariff

Worked Electricity Example: 4.5-Hour Print Job

For a 4.50-hour total job (0.10 h / 6 min preheat + 4.40 h steady-state printing):

• PLA (60 °C bed, 210 °C nozzle): E_PLA = (260 W × 0.10 h + 80 W × 4.40 h) / 1,000 = 0.378 kWh.
• PETG (85 °C bed, 240 °C nozzle): E_PETG = (280 W × 0.10 h + 105 W × 4.40 h) / 1,000 = 0.490 kWh.
• ASA (110 °C bed, 260 °C nozzle): E_ASA = (300 W × 0.10 h + 120 W × 4.40 h) / 1,000 = 0.558 kWh.

If you run an active filament dryer (~45 W average draw; see Filament Moisture, Hydrolysis, and Drying Temperatures) for 6 hours alongside a PETG or ASA print, add 0.27 kWh to the job total.

Region & Typical Residential Tariff	PLA (0.378 kWh)	PETG (0.490 kWh)	ASA (0.558 kWh)
United States ($0.18 USD / kWh)	$0.068 (~$0.07)	$0.088 (~$0.09)	$0.100 ($0.10)
Canada ($0.15 CAD / kWh)	$0.057 CAD	$0.074 CAD	$0.084 CAD
United Kingdom (£0.26 GBP / kWh)	£0.098 GBP	£0.127 GBP	£0.145 GBP
Australia ($0.32 AUD / kWh)	$0.121 AUD	$0.157 AUD	$0.179 AUD

Nozzle Wear, Build Sheets, and Printer Depreciation

While electricity costs roughly $0.015–$0.025 USD per print hour, machine depreciation and consumable wear cost 8 to 10 times more per hour ($0.20–$0.25/h):

1. Printer capital amortization: If a $650 printer requires $100 in belts, fans, and bearings over a 4,000-hour service life and retains a $50 salvage value, depreciation is ($650 + $100 − $50) / 4,000 h = $0.175 / hour. The Prusa FAQ notes an average maintenance interval around 800 print hours for routine bearing care and nozzle inspection.
2. Nozzle and build-sheet wear: As detailed in Different Nozzle Types and Nozzle Size vs Layer Height Limits, standard brass nozzles last 500–800 hours with unfilled polymers (~$0.012/h for an $8 V6 nozzle), while abrasive carbon-fiber or glow filaments require a hardened steel or wear-resistant nozzle ($25–$50 over 1,000–1,500 hours). Adding a $35 PEI sheet lasting 1,500 hours (~$0.023/h) brings combined hardware and consumable wear to $0.21 per print hour ($0.95 for a 4.5-hour print).

Complete Worked Cost Breakdown (PLA vs PETG, 40.0 m, 4.5 Hours)

Combining all four terms for our 40.00 m (96.21 cm³), 4.50-hour print at US baseline rates ($22.00/kg filament, $0.18/kWh electricity, $0.21/h hardware/nozzle wear, and 5% failure margin f_fail = 0.05):

Cost Component	Formula / Basis	1.75 mm PLA (1.24 g/cm³)	1.75 mm PETG (1.27 g/cm³)	Share of Total
1. Filament material	96.21 cm³ × ρ × $0.022/g	119.30 g → $2.62	122.19 g → $2.69	~68.6%
2. Electrical energy	E_kWh × $0.18/kWh (4.5 h)	0.378 kWh → $0.07	0.490 kWh → $0.09	~2.0%
3. Printer & nozzle wear	4.50 h × $0.210/h	$0.95	$0.95	~24.6%
Direct subtotal	C_fil + C_elec + C_hw	$3.64	$3.73	95.2%
4. Failure margin (5%)	Subtotal × 0.05	$0.18	$0.19	~4.8%
Total true part cost	Subtotal × 1.05	$3.82 USD	$3.92 USD	100.0%

Bare filament weight ($2.62–$2.69) accounts for only about two-thirds of the true $3.82–$3.92 cost of putting a finished, dimensionally verified part on the workbench.