Voltage Drop & Wire Size Calculator
Find out how much voltage drops along a long wire run and which cable size is safe to use. Enter the load, length and current, and get the drop and recommended wire instantly.
Recommended Cable
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Voltage Drop
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Drop %
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⚠ Voltage drop is more than 5% — use a thicker cable, otherwise the appliance will run weak and the wire can get hot.
Note: The recommended size is the smallest standard cable on which the drop stays ≤ 5% and the ampacity is also enough for the load (indicative ampacity is used).
How to use
- Enter the load in amperes, or select watts mode and enter watts + voltage.
- Select the one-way distance, voltage and cable material.
- The recommended mm², voltage drop and percentage show instantly. You can also select a cable of your choice and check its drop.
Tips
- Longer runs and thinner wire both raise the drop — keeping the run short is the cheapest fix.
- If the drop is too high, sizing up the wire is safer than ignoring it.
- For real wiring work, verify the result against your local electrical code.
Formula: Drop (V) = 2 × Distance (m) × Current (A) × Resistivity ÷ Cable Area (mm²). For wiring work, call Azlaan Electric AC Solar Center, Faisalabad — 0300-8987448.