3D Printing Calculators

FDM hardware & mechanics

Bed Heater Power Requirement

A heater sized only to hold 60 °C would take forever to get there. This estimate combines the energy needed to warm the plate in the time you choose with the heat it loses from its top and underside, then adds a margin.

Inputs

Units
mm
mm

Sets how much heat each cm³ of plate stores per °C.

mm

Plate plus anything heated with it. 4 mm of glass ≈ 3 mm of aluminium; a spring-steel sheet with its magnet ≈ 2 mm.

min

How fast the bed should get from ambient to target. Halving it roughly doubles the watts when heat-up dominates.

°C
°C

Room air around the bed; inside an enclosure, use the chamber temperature.

%

Covers mains sag, pad tolerance and losses the model misses.

Terms of Service

Results

Please tick the box above to display the Result.

Calculation method

Heat loss is H × ΔT, where ΔT is target minus ambient and H = area × 12 W/m²K × 1.75 for an open plate, or × 1.25 when the underside is insulated. 12 W/m²K is natural convection plus radiation from a PEI or glass build surface; the factor adds the underside. Heat capacity is C = area × thickness × volumetric heat capacity: aluminium 2.43, steel 3.85, borosilicate glass 1.85 and FR-4 PCB 2.0 J/cm³K. A plate fed a constant power P warms as ΔT(t) = (P / H) × (1 − e^(−H·t/C)), so the power that reaches the target in heat-up time t is P = H × ΔT / (1 − e^(−H·t/C)). Holding power is H × ΔT. The recommended wattage is the heat-up power × (1 + margin/100), and power density divides it by the plate area in cm². Width, depth and thickness convert to inches and temperatures to °F with the imperial toggle. The result is invalid when the target is not hotter than ambient.

Exact formula

H = A × 12 × (1.75 open | 1.25 insulated) W/K; C = A × thickness × ρc; P_heat = H ΔT / (1 − exp(−H t / C)); P_hold = H ΔT; recommended = P_heat × (1 + margin/100). Limits: Lumped plate with loss coefficients for 50–70 °C beds; radiation grows faster above 100 °C, and clips, edges and the frame add loss. Invalid if target ≤ ambient.

Insulation that actually counts

Cork, silicone foam or felt under the heater is the insulated case. It removes most of the underside loss, not the top: the build surface still loses about 12 W/m²K. A sheet of paper is not insulation.

Frequently asked questions

Why is the holding power so much lower than the heater?

Holding only replaces losses. Heating from cold also has to put energy into the plate, and a heater sized exactly to the losses would approach the target ever more slowly and never quite reach it. The heat-up output covers both.

PEI spring steel or glass on top?

Add its thermal mass to the heated thickness: 4 mm of glass is about 3 mm of aluminium, a 0.5 mm spring-steel sheet plus its magnet about 2 mm. It changes the heat-up power, not the holding power.

120 V vs 24 V pads?

Watts are watts. Voltage only changes current and the connector you must not cheap out on.

Can I run ABS at 110 °C with this?

Raise the target and expect real losses above this model, because radiation grows quickly past 100 °C. Use a bigger margin, insulate the underside and consider an enclosure — then enter the chamber temperature as ambient.

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