Wire Size and Voltage Drop Calculator
K method · SSC-2026.1
Minimum size
6 AWG · 13.3 mm²
Single conductor set
Voltage drop
3.69 V
1.54% · end 236.3 V
Power loss
184 W
I²R at the operating current
Required ampacity
62.5 A
Each conductor 65 A
Material estimate
$597.00
3 conductors + EMT
Conductor weight
22.1 lb
10.0 kg · approximate insulated weight
Circle diameters track circular mils. The drawing is a schematic, not a conduit-fill layout.
| Item | Net | Waste | Order | Unit price | Line total | Source Spec Material / Tool |
|---|---|---|---|---|---|---|
| copper 6 AWG · 13.3 mm² | 75 ft one way | cuts excluded | 3 conductors | USD | $458.25 | Source Spec Material / Tool |
| EMT conduit | 75 ft | — | 75 ft | USD | $138.75 | Source Spec Material / Tool |
| 50 A breaker | 2-pole | — | 1 | Match the calculated load | — | Source Spec Material / Tool |
Source links open a product search on the Amazon storefront for the selected currency. SiteSpecCalc may earn a commission. The link does not change the quantities above.
| Material | Minimum size | mm² | Drop | End voltage | Loss |
|---|---|---|---|---|---|
| copper | 6 AWG · 13.3 mm² | 13.3 | 1.54% | 236.3 V | 184 W |
| aluminum | 4 AWG · 21.2 mm² | 21.2 | 1.59% | 236.2 V | 190 W |
| Distance | Minimum size | Drop | Percent | End voltage |
|---|---|---|---|---|
| 50 ft | 6 AWG · 13.3 mm² | 2.46 V | 1.02% | 237.5 V |
| 75 ft | 6 AWG · 13.3 mm² | 3.69 V | 1.54% | 236.3 V |
| 100 ft | 6 AWG · 13.3 mm² | 4.92 V | 2.05% | 235.1 V |
Show the deterministic formula
Single phase: Vdrop = 2 × K × I × D / cmil. Three phase: Vdrop = 1.732 × K × I × D / cmil. K is 12.9 for copper and 21.2 for aluminum. D is one-way feet.
Percent drop = Vdrop ÷ source voltage × 100. Green is 3% or less, amber is 3 to 5%, and red is over 5%. Power loss is I²R on the current-carrying conductors.
The smallest conductor that meets both the ampacity (125% when continuous) and the drop limit is selected. Ampacity does not include bundling or temperature correction.
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Project: Wire Size and Voltage Drop Calculator
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This sheet is an estimate for ordering and layout discussion. It is not a sealed design. Confirm the quantities with a licensed local professional and the authority having jurisdiction before you buy or build.