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240V Voltage Drop Calculator

Preset for 240 V single-phase — residential heavy loads — ranges, dryers, EV chargers and subpanels. A 3% budget at this voltage is 7.2 V.

Voltage Drop
Find Wire Size
Max Length
Advanced — units, power factor, parallel sets, energy cost
PASS
Voltage Drop
Percent Drop
Voltage at Load
Power Lost
Wire Resistance
Ampacity 75°C
0%3% branch5% total8%+

Max one-way distance at 3% (7.2 V) — copper

Size \ Amps15 A20 A30 A50 A100 A
14 AWG7859
12 AWG12493
10 AWG19814999
8 AWG31423615794
6 AWG489367244147
4 AWG779584390234
3 AWG980735490294147
2 AWG1237928619371186
1 AWG15581169779468234
1/0 AWG19671475984590295
2/0 AWG248218611241745372
3/0 AWG313323501567940470
4/0 AWG3947296119741184592

Cells are blank where the size is below the 75 °C ampacity for that load.

Frequently Asked Questions

What is 3% of 240 volts?

7.2 V — the recommended maximum branch-circuit drop at this voltage. The 5% total budget is 12.0 V.

Built & maintained by Murugan Vellaichamy · Every calculation verified against NEC Chapter 9 Table 8 & Table 310.16 published values · Informational reference — not engineering advice