Kanthal, nichrome or constantan: choosing resistance and heating wire
Differences between FeCrAl (Kanthal), nickel-chrome and copper-nickel wires, with example data and ordering tips. · Updated
Three common alloy families
- Iron-chromium-aluminium (FeCrAl, for example Kanthal A-1): for high-temperature heating elements in air.
- Nickel-chromium (nichrome, typically 80/20): for heating elements needing good ductility and high-temperature strength.
- Copper-nickel (constantan, Eureka type): for resistors and low-temperature applications where a stable resistance is more important than heat.
Example data: Kanthal A-1, 1.00 mm round wire (manufacturer datasheet)
- Resistivity: 1.45 Ω·mm²/m at 20 °C, giving about 1.85 Ω per metre for 1.00 mm wire (calculated).
- Maximum continuous operating temperature in air: 1400 °C, subject to the manufacturer's service conditions.
- Density: 7.10 g/cm³; melting point about 1500 °C (not an operating limit).
How to choose and order
- Start from the element's power and supply voltage to work out the required resistance, then choose a wire diameter and length.
- Element design temperature should stay well below the alloy's maximum, especially in contact with insulation.
- Tell us the alloy (or application), diameter or SWG, and the quantity in metres or kilograms.
Frequently asked questions
What is the resistance of 1 mm Kanthal A-1 wire?
About 1.85 ohms per metre at 20 °C, calculated from the manufacturer's resistivity of 1.45 Ω·mm²/m. Resistance rises slightly at operating temperature.
Kanthal or nichrome for a heater?
FeCrAl (Kanthal) allows higher maximum temperatures in air and has lower density, while nichrome is more ductile and stronger when hot. The choice depends on temperature, atmosphere, element support and forming requirements.