Calculator Inputs
Example Data Table
These reference values help users test the calculator quickly. Actual values vary with purity, alloy content, and temperature.
| Material | Resistivity at 20°C (Ω·m) | Approx. α (1/°C) | Typical Use |
|---|---|---|---|
| Silver | 1.59 × 10-8 | 0.0038 | High-conductivity contacts |
| Copper | 1.68 × 10-8 | 0.00393 | General wiring |
| Aluminum | 2.82 × 10-8 | 0.00429 | Power transmission |
| Iron | 9.71 × 10-8 | 0.00500 | Structural conductors |
| Nichrome | 1.10 × 10-6 | 0.00040 | Heating elements |
| Carbon Steel | 1.43 × 10-7 | 0.00600 | Industrial components |
Formula Used
R = ρL / A
ρT = ρref × [1 + α(T - Tref)]
Reffective = Rsingle / n
Here, R is resistance, ρ is resistivity, L is conductor length, and A is cross-sectional area. Temperature changes alter resistivity, so the advanced version corrects the base value before computing resistance.
When voltage is entered, the calculator estimates current and power using Ohm’s law. When current is entered, it estimates voltage drop, power loss, and current density.
How to Use This Calculator
- Select the resistivity unit that matches your source data.
- Enter conductor length and choose the correct length unit.
- Choose whether you want to enter area directly, use diameter, or use width and thickness.
- Apply temperature correction if the conductor works above or below the reference temperature.
- Set the number of identical parallel paths when more than one conductor shares the load.
- Add optional voltage or current to estimate electrical performance beyond resistance.
- Press the calculate button to display results above the form.
- Use the CSV or PDF buttons to export the calculation summary.
FAQs
1) What does resistivity mean?
Resistivity measures how strongly a material opposes electric current. It is a material property, not a shape property. Resistance changes with size, but resistivity belongs to the material itself.
2) Why does length increase resistance?
A longer conductor gives electrons a longer path to travel. That creates more opposition to current flow. In the formula, resistance rises directly with conductor length.
3) Why does larger area reduce resistance?
A larger cross-sectional area gives current more room to move. This lowers opposition and reduces resistance. In the equation, area appears in the denominator, so bigger area means smaller resistance.
4) When should I use temperature correction?
Use temperature correction when conductor temperature differs from the resistivity reference temperature. This is important in power wiring, heating elements, and high-current circuits where conductor temperature may rise noticeably.
5) Can I use diameter instead of area?
Yes. Circular wires are often specified by diameter, not area. This calculator converts diameter into cross-sectional area automatically before finding resistance.
6) What do parallel paths change?
Parallel conductors share current, so their combined resistance drops. If all paths are identical, effective resistance equals single-path resistance divided by the number of paths.
7) What graph does this page show?
The Plotly graph shows how effective resistance changes with conductor length while keeping the other selected parameters fixed. It helps users visualize sensitivity and design trends.
8) Is this useful for voltage drop checks?
Yes. Enter current to estimate voltage drop across the conductor. Enter voltage to estimate current and power. That makes the tool useful for wiring, electronics, and quick sizing studies.