About the Wire Gauge Calculator
What is the Wire Gauge Calculator?
Long cable runs lose voltage. This wire size calculator finds the smallest cross-section that keeps the voltage drop within your limit, then rounds up to the next standard metric size.
It uses conductor resistance at a 70 °C operating temperature and also shows the nearest American Wire Gauge (AWG).
How to use the Wire Gauge Calculator
- Supply (sample: Single-phase / DC (2 conductors))
- Load Current (A) (sample: 32)
- Cable Length, One Way (m) (sample: 25)
- Supply Voltage (V) (sample: 230)
- Allowed Voltage Drop (%) (sample: 3)
- Conductor (sample: Copper)
- Press Find Wire Size (results also refresh as you type). The result card shows the Recommended Cable Size, along with Minimum cross-section for the voltage drop, Voltage drop with this size, Nearest AWG and Also check.
Formula used
A (mm²) = k × L × I × ρ ÷ V_drop
- k = 2 for single-phase or DC, √3 for three-phase
- ρ = resistivity at 70 °C: copper ≈ 0.0206, aluminium ≈ 0.0339 Ω·mm²/m
- V_drop = supply voltage × allowed drop %
Electrical work on mains supplies must be done by a licensed electrician, following IS 732 and the CEA safety regulations.
Worked example
These are the sample values already filled in the calculator above, and the result it returns for them:
| Input | Sample value |
|---|---|
| Supply | Single-phase / DC (2 conductors) |
| Load Current (A) | 32 |
| Cable Length, One Way (m) | 25 |
| Supply Voltage (V) | 230 |
| Allowed Voltage Drop (%) | 3 |
| Conductor | Copper |
| Result | Value |
|---|---|
| Recommended Cable Size | 6 mm² |
| Minimum cross-section for the voltage drop | 4.772 mm² |
| Voltage drop with this size | 2.39% |
| Nearest AWG | 9 |
| Also check | The cable's current rating for its installation method (IS 694 / manufacturer tables) |
Tips for using the Wire Gauge Calculator
- Always check the cable's current-carrying capacity as well; the larger of the two sizes applies.
- Aluminium needs about 1.6 times the cross-section of copper for the same drop.