Calculating your wire resistance is straightforward once you know the Wire Resistance formula and what each input means. This guide explains the method in plain language, walks through a manual calculation, and gives worked examples you can follow — then you can do it instantly with the Wire Resistance Calculator.
What is Wire Resistance?
The Wire Resistance calculation tells you your wire resistance from a few simple inputs. The figure you are solving for here is the wire resistance.
The Wire Resistance formula
The core formula is:
Wire resistance = Resistivity (Ω·mm² ÷ m) × Wire length ÷ Cross-section areaHere is what each input means:
- Wire length — a value measured in m. Example: 10 m.
- Cross-section area — a value measured in mm². Example: 1.5 mm².
- Resistivity (Ω·mm²/m) — a number. Example: 0.0168.
How to calculate it step by step
- Write down the wire length (for example, 10 m).
- Write down the cross-section area (for example, 1.5 mm²).
- Write down the resistivity (Ω·mm²/m) (for example, 0.0168).
- Apply the formula above to get your wire resistance.
- Double-check the result with the Wire Resistance Calculator.
Worked examples
Example 1
| Input / Output | Value |
|---|---|
| Wire length | 10 m |
| Cross-section area | 1.5 mm² |
| Resistivity (Ω·mm²/m) | 0.0168 |
| Wire resistance | 0.11200 |
With wire length of 10 m, cross-section area of 1.5 mm² and resistivity (Ω·mm²/m) of 0.0168, the wire resistance works out to 0.11200.
Example 2
With wire length of 20 m, cross-section area of 1.5 mm² and resistivity (Ω·mm²/m) of 0.0168, the wire resistance works out to 0.22400.
| Result | Value |
|---|---|
| Wire resistance | 0.22400 |
Example 3
With wire length of 5 m, cross-section area of 1.5 mm² and resistivity (Ω·mm²/m) of 0.0168, the wire resistance works out to 0.05600.
| Result | Value |
|---|---|
| Wire resistance | 0.05600 |
Tips for an accurate result
- Keep your units consistent — mixing, say, months with years or grams with kilograms is the most common source of error.
- Round only at the very end. Rounding inputs early can shift the final answer noticeably.
- Re-run the numbers whenever an input changes, rather than estimating from an old result.
Prefer not to do the maths by hand? — the Wire Resistance Calculator does it instantly, for free, with the formula and a worked example built in.
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