220V Wire Size Calculator — AWG Gauge & Voltage Drop
Select the system voltage (220, 230, or 240 V), enter the load current, one-way wire length, and the maximum voltage drop you can accept. The calculator returns the minimum AWG copper gauge that keeps the drop within your limit.
V
A
ft
Length unit
%
- 1
Allowable voltage drop
3 % × 220 V ÷ 100 = 6.6 V - 2
Required circular mils
2 × 10.75 × 15 × 50 ÷ 6.6 = 2,443The smallest AWG gauge whose CM ≥ this value is the minimum safe wire size.
How does this calculator work?
Required CM = 2 × 10.75 × I × L_ft / V_drop; pick the smallest AWG copper gauge with at least that many circular mils. At 220 V, a 3 % drop limit is 6.6 V, letting you use thinner wire for the same current vs. 12 V DC — always cross-check against the gauge's ampacity rating.
Formula
How this is calculated
The same circular-mils formula used for low-voltage DC applies equally to AC single-phase circuits, assuming a unity power factor (purely resistive load). Required circular mils = 2 × 10.75 × I × L / V_drop, where 10.75 is the copper resistivity constant in Ω·CM/ft, 2× accounts for the outgoing and return conductors, and V_drop is the absolute voltage drop allowed (e.g. 3 % of 220 V = 6.6 V). The calculator finds the thinnest standard AWG gauge whose cross-sectional area in circular mils meets or exceeds that requirement.
At 220 V the same absolute drop represents a much smaller percentage than at 12 V, so wire runs can be considerably longer before the voltage drop limit is hit. For example, a 15 A circuit running 50 ft at 220 V with a 3 % drop limit needs only AWG 16, whereas the same current at 12 V over 10 ft already needs AWG 12.
For inductive loads (motors, compressors) the actual current may be higher during startup — size the wire for the locked-rotor or full-load ampacity shown on the motor nameplate. Also confirm the chosen gauge stays within its ampacity rating (the column shown in the results) and apply any NEC derating for conduit fill, ambient temperature, or continuous loads over 80 %.
Frequently asked questions
Yes. The system voltage field is editable — change it to 230 or 240 (common in Europe, Australia, and some US regions) and the voltage-drop limit and percentage recalculate automatically.
The NEC recommends ≤ 3 % on the branch circuit and ≤ 5 % total from the service panel to the load. For sensitive electronics or long runs, use 2 % or less.
Many countries use IEC cross-sectional area sizes in mm² (e.g. 1.5 mm², 2.5 mm²) instead of AWG. The metre entry converts your length to feet for the calculation, but the result is expressed in AWG. Common equivalencies: AWG 12 ≈ 3.3 mm², AWG 10 ≈ 5.3 mm².
TG we-Calculate Editorial Team. (2026). 220V Wire Size Calculator — AWG Gauge & Voltage Drop [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/220v-wire-size-calculator
TG we-Calculate Editorial Team. "220V Wire Size Calculator — AWG Gauge & Voltage Drop." TG we-Calculate. 2026. https://we-calculate.com/calculator/220v-wire-size-calculator.
TG we-Calculate Editorial Team, "220V Wire Size Calculator — AWG Gauge & Voltage Drop," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/220v-wire-size-calculator
@misc{wecalculate_220v_wire_size_calculator, title = {220V Wire Size Calculator — AWG Gauge & Voltage Drop}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/220v-wire-size-calculator}}, year = {2026}, note = {TG we-Calculate} }
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