Electric Heating Calculator: Element Wire Length, Heating Time, Radiation Loss and Electrolysis

How this calculator works

Choose what you want. For a heating element enter the power, the voltage, the wire resistivity and diameter. It gives the resistance, the current, the wire length and the surface loading.

For the time to heat enter the mass, the specific heat, the temperature rise, the power and the efficiency.

For radiation enter the two temperatures, the area and the emissivity. For electrolysis enter the current, the time, the molar mass and the valency.

Formulas used

• R = \frac{V^2}{P}
• \ell = \frac{RA}{\rho}
• Q = mc\,\Delta T,\quad t = \frac{Q}{\eta P}
• P = \sigma\varepsilon A(T_1^4 - T_2^4)
• m = \frac{MIt}{zF}

Worked example

With the default numbers in the calculator above:

1. Resistance of the element: 17.63 ohm
2. Current: 13.04 A
3. Length of wire needed: 18.13 m of 1.20 mm wire
4. Surface loading (power for each square centimetre of wire surface): 4.39 W/cm2

Change the numbers in the calculator to see the full working, every step, for your own case.

A second worked example

A different case, with these numbers: What do you want? Time to heat a mass.

1. Heat needed: 12558.00 kJ (3.49 kWh)
2. Time to heat: 77.52 min (1.29 hours)
3. Electrical energy used: 3.88 kWh

Common questions

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Got a question about this? Ask an engineering question and get a plain-language answer with references.

Further reading: Partab, Art and Science of Utilisation of Electrical Energy; any university physics text (Stefan-Boltzmann law, Faraday's laws).

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