Voltage Drop & Cable Run Calculator
Work out DC voltage drop over a cable run for cameras, access control, intercoms and alarm devices — and the maximum run length for your chosen cable.
Inputs
Results
Voltage drop
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Drop as % of supply
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Voltage at device
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Load current
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Max run at selected drop limit
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Calculated for two-wire copper DC circuits (out and back) using resistivity 0.0175 Ω·mm²/m at 20°C. Results are a guide only — check your device's minimum operating voltage (many 12V cameras need at least 11V) and always verify with a meter under load. For long runs consider stepping up to 24V or using PoE.