List of symbols
| Unit for calculation | |||
| Symbol | Meaning | Metric | Imperial |
| AC | Surface area of heating conductor | cm2 | in2 |
| b | Width (ribbon or strip) | mm | in |
| Ct | Temperature factor (ratio of resistivity at operating temperature to resistivity at room temperature) | ||
| d | Wire diameter | mm | in |
| D | Outer coil diameter | mm | in |
| I | Current | A | A |
| L | Length of heating conductor | m | ft |
| Le | Coil length | mm | in |
| n | Number of turns | ||
| p | Surface load of heating element | W/cm2 | W/in2 |
| P | Power | W | W |
| q | Cross-sectional area of heating conductor | mm2 | in2 |
| r | Relative pitch | ||
| RT | Resistance at working temperature | Ω | Ω |
| R20 | Resistance at room temperature (20°C, 68°F) | Ω | Ω |
| s | Pitch | mm | in |
| t | Thickness (ribbon or strip) | mm | in |
| T | Temperature | K, °C | K, °F |
| U | Voltage | V | V |
| α | Temperature coefficient of resistivity | K-1 | °F-1 |
| γ | Density (old marking) | g/cm3 | lb/in3 |
| ρ | Resistivity | Ω mm2/m | Ω/smf /cmf* |
| 10 | Balancing factor used in the formulas makes possible that the values can be used with units of section 1: e.g. wire diameter, d, in millimeter (mm) or inch (in) is different from length of heating conductor, l, in meter (m) or foot (ft) |
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