Calculator KB-48
Nichrome Coil Calculator
Foam cutter, dryer, hot plate: calculate the required wire length in a second.
Result
In brief: Calculate a nichrome or Kanthal heater: wire length based on voltage, power, and diameter; resistance, current, and coil surface load. Example: Wire length: 9.44 m.
Calculation example
| Voltage | 230 V |
|---|---|
| Power | 1000 W |
| Wire diameter | 0.5 mm |
| Material | Nichrome Kh20N80 (NiCr 80/20) |
| Wire length | 9.44 m |
|---|---|
| Coil resistance | 52.9 Ω |
| Current | 4.348 A |
| Surface load | 6.74 W/cm² |
How it is calculated
L = R · S / ρ
Load = P / (π · d · L)
Resistance follows from voltage and power, and length from resistance and cross-sectional area. Surface load indicates how hot the wire will get: the more power per square centimeter, the hotter it gets.
What to look for
- In open air, 3–8 W/cm² is usually safe; with airflow or liquid cooling, you can go higher.
- Nichrome resistance changes little as it heats up, while Kanthal changes more noticeably. Check against the first current measurement.
Frequently asked questions
How much nichrome wire do you need for 1 kW at 230 V?
The heating element needs a resistance of 52.9 Ω. With 0.5 mm wire, that's 9.44 m, drawing 4.35 A.
How do you choose a nichrome wire diameter?
Use the surface loading as a guide: 1 kW on 0.5 mm wire gives 6.74 W/cm², while 3–8 W/cm² is usually safe in air. Thicker wire runs cooler and lasts longer, but you need more of it.
How do you calculate a foam cutter?
The frame sets the length, so you choose the wire diameter and voltage. A 30 cm length of 0.3 mm wire has a resistance of about 4.7 Ω and draws roughly 2.6 A at 12 V.
