220V Wire Size Calculator - Copper or Aluminum mm2 and AWG
220V wire size calculator for single-phase loads. Enter voltage, current, distance, and conductor material to get mm2, AWG, and diameter.
220V Wire Size Calculator
Results
What Is 220V Wire Size Calculator?
A 220V wire size calculator turns four measurements - supply voltage, load current, one-way cable run, and conductor material - into the minimum cross-sectional area your cable needs to stay within a chosen voltage-drop target. The result comes back in mm\u00b2 for metric labels and in AWG for North American projects, so the same answer works whether you are buying twin-and-earth at the wholesaler or ordering THHN from a supply house.
- • Single-Phase 220 V Outlets: Sizing the run from the breaker panel to a 220 V workshop outlet or window AC.
- • 220 V Pumps and Compressors: Sizing the feeder cable for a submersible pump or pool pump where voltage drop drives the choice.
- • EV Charging at 220 V: Sizing a Level 2 EV charger cable run where target current and distance drive the AWG.
- • Outdoor 220 V Lighting and Outbuildings: Sizing the feed to a detached garage or yard lighting circuit where distance pushes the cable up.
Wire sizing for a 220 V single-phase circuit is a two-part problem: the cable has to carry the load current safely without overheating, and it has to deliver enough voltage at the far end that the appliance actually starts. The current rating is fixed by the equipment; the voltage-drop part is what the calculator solves.
When the 220V wire size result needs a sanity check against the basic V = I x R relationship, Ohm's Law calculator shows how the same current, voltage, and resistance values line up against the cross-section the formula recommends.
How 220V Wire Size Calculator Works
The 220V wire size formula divides the voltage loss allowed by the resistivity, current, and run length of the conductor. The factor of two accounts for both conductors in the single-phase loop, and the voltage drop is entered as a decimal fraction of the supply voltage.
- Voltage V: Single-phase supply voltage in volts. Default 220 V.
- Current I: Maximum continuous load current in amperes.
- Distance L: One-way cable length in metres. Doubled internally.
- Resistivity \u03c1: Copper 1.68 x 10^-8; aluminum 2.82 x 10^-8 at 20 C.
- Drop fraction: Allowed voltage drop as a decimal. 3 percent is 0.03.
The mm\u00b2 result converts to AWG by rounding up to the next standard gauge. That round-up keeps the cable inside the voltage-drop target, because real cables are slightly smaller than the geometric ideal and connectors add their own resistance.
Worked example: 30 A sub-panel feed, 30 m copper, 3 percent drop at 220 V
V = 220, I = 30, L = 30, material = copper, percentDrop = 3.
dropFraction = 0.03; A = (2 * 30 * 1.68e-8 * 30) / (220 * 0.03) = 3.024e-5 / 6.6 = 4.58 mm\u00b2. Round up = 10 AWG (5.26 mm\u00b2).
4.58 mm\u00b2, 10 AWG, 2.41 mm diameter, 6.6 V drop at the load.
A 30 A run of 30 m sits at the boundary where voltage drop drives the cable. 10 AWG handles 30 A at 75 C ampacity and limits the drop to 6.6 V, comfortably inside the 3 percent branch-circuit target.
According to Omni Calculator, 220 Volt Wire Size, the formula is A = (2 x I x rho x L) / (V x percentDrop), which gives 6 AWG for a 50 A, 46 m copper run at 220 V and 3 percent drop.
According to Wikipedia, Electrical resistivity and conductivity, copper has 1.68 x 10^-8 and aluminum has 2.82 x 10^-8 ohm-metres at 20 C, which are the standard values used in single-phase wire sizing formulas.
When the run is on a DC feeder or different nominal voltage, voltage drop calculator handles the same math with explicit input fields so the 220V result can be cross-checked against a different cable layout.
Key Concepts Explained
Four small concepts explain what the cross-section number means and how to read it next to the ampacity rating on the cable reel.
Cross-Section vs Diameter
Cross-sectional area (mm\u00b2 or AWG) drives resistance. Diameter fits the conduit. A cable with twice the diameter has four times the cross-section.
Voltage Drop vs Ampacity
Ampacity is the maximum current without overheating. Voltage drop is the voltage lost at that current. For runs above 20 m on 220 V, voltage drop usually forces you to step up one or two AWG sizes.
One-Way vs Loop Length
The formula uses one-way distance and doubles it internally. Typing the loop length would over-size the cable by a factor of two.
Copper vs Aluminum
Aluminum has roughly 68 percent of copper's conductivity, so an aluminum cable must be larger for the same voltage drop. Switching materials usually means stepping up two AWG sizes.
The cross-section in mm\u00b2 ties together resistance, ampacity, and voltage drop. Once you know the mm\u00b2, the cable reel, the conduit fill table, and the breaker-lug rating all line up against the same value.
When the chosen cable has to satisfy ampacity and conduit fill alongside voltage drop, wire gauge calculator produces the matching AWG size from load, distance, and a 12 V, 24 V, or solar-panel context, so the 220V result can be paired with the right cable for each part of the installation.
How to Use This Calculator
Five short steps take you from a 220 V load on the workbench to a cross-section and AWG size that lines up with the breaker you plan to fit.
- 1 Confirm the Supply Voltage: Read the supply voltage at the breaker panel. Type 220 V, or 230 V or 240 V where the local grid delivers that.
- 2 Find the Load Current: Take the full-load current from the equipment nameplate, or the next standard breaker size. A 30 A breaker on a continuous load is sized at 24 A (80 percent rule); use the breaker size, not the derated value.
- 3 Measure the One-Way Run: Measure the cable route from the breaker to the equipment terminal box. Do not add the return length - the calculator doubles the one-way distance internally.
- 4 Pick the Material and the Drop Target: Choose copper for branch circuits and most indoor runs, aluminum for long outdoor feeders where cost matters. Type the voltage-drop target (3 percent for branch circuits, 5 percent for feeder plus branch combined).
- 5 Read the Cross-Section and AWG: The results panel shows the minimum mm\u00b2, the AWG size that meets that cross-section, the cable diameter in mm and inches, and the actual voltage drop in volts at the load.
Picture a workshop with a 220 V, 30 A table saw 25 m from the breaker panel. Type 220 V, 30 A, 25 m, copper, and 3 percent. The calculator returns about 3.81 mm\u00b2, which rounds up to 10 AWG (5.26 mm\u00b2), a 2.59 mm diameter, and a 6.6 V drop. 10 AWG copper pairs with a 30 A breaker and fits a standard 3/4 inch conduit run.
When the chosen cable is ready and the next step is the breaker rating, circuit breaker size calculator picks the correct breaker amperage for continuous and motor loads so the AWG from this calculator lines up with the overcurrent protection in the panel.
Benefits of Using This Calculator
A small dedicated 220V wire size calculator saves time on the math and produces a result that lines up with the cable reel, the conduit fill table, and the breaker lug at the same time.
- • Stops the Voltage-Drop Guesswork: Replaces the loop-length-times-resistivity division with a single typed entry.
- • Speaks mm\u00b2 and AWG at the Same Time: Returns the cross-section in mm\u00b2 for the metric reel and in AWG for the North American project.
- • Covers Copper and Aluminum: Lets the user pick the conductor material so the resistivity matches the cable.
- • Configurable Voltage-Drop Target: Accepts any allowed drop from 0.1 to 20 percent. Default 3 percent matches NEC branch-circuit practice.
- • Shows the Diameter for Conduit Fill: Returns the conductor diameter in mm and inches next to the cross-section.
The biggest practical benefit is that the calculator does the doubling internally. Typing the loop length is one of the most common mistakes on a 220 V install, and getting it wrong by a factor of two either under-sizes the cable or wastes money on a heavier gauge.
When the project also has to plan the total panel load before sizing any individual branch, electrical load calculator adds up the running and starting watts across the whole house so the 220V run fits inside the service entrance rating.
Factors That Affect Your Results
Five physical and code factors shift the recommended mm\u00b2 and AWG up or down from the textbook number the formula returns.
Run Length
Voltage drop scales linearly with length. Doubling the one-way distance doubles the required cross-section.
Conductor Material
Aluminum has higher resistivity than copper, so the recommended mm\u00b2 grows by the resistivity ratio (about 1.7x).
Allowable Voltage Drop
Cutting the percent drop from 5 percent to 3 percent increases the required cross-section by a factor of 1.67.
Supply Voltage
Voltage drop scales inversely with supply voltage. The same 30 A load on 110 V needs four times the cross-section of the same load on 220 V.
Ambient Temperature and Conduit Fill
Cables in conduit bundles or in hot attics need an ampacity correction, which can force the next-larger AWG size even when voltage drop is comfortable.
- • The formula assumes a single-phase loop with the same cable in both conductors and ignores the small resistance added by terminations and splices.
- • Voltage-drop sizing is a code minimum. The recommended mm\u00b2 also has to satisfy the ampacity tables for the cable type and the local electrical code.
Practical installations also depend on the cable insulation. THHN, NM-B, and PVC-jacketed cable have different ampacity ratings at the same AWG, so the same mm\u00b2 from this calculator will deliver different usable currents in different cable types. Cross-check the AWG against the cable reel label and the local electrical code before you commit to a run.
According to Wikipedia, American wire gauge, the AWG system is a 39-step geometric progression from 36 AWG (0.127 mm diameter) to 0000 AWG with a 92x diameter ratio, giving the cross-section formula A_mm2 = 0.012668 x 92^((36 - n) / 19.5) used to convert between mm^2 and AWG.
Frequently Asked Questions
Q: What wire size do I need for a 220V circuit?
A: Match the cross-section to the load current, run length, and allowed voltage drop. A 30 A workshop run of 25 m copper at 220 V and a 3 percent drop comes out at about 3.81 mm², which rounds up to 10 AWG.
Q: How do you calculate wire size for 220V?
A: Use A = (2 x I x rho x L) / (V x dropFraction). The factor of two accounts for both conductors in the single-phase loop; rho is 1.68 x 10^-8 ohm-metres for copper or 2.82 x 10^-8 for aluminum; dropFraction is the allowed drop as a decimal.
Q: What gauge wire for 50 amp 220V?
A: For a 50 A, 46 m copper run at 220 V with a 3 percent drop, the formula gives 11.71 mm², which rounds up to 6 AWG. A shorter 25 m copper run at the same current drops to 6.36 mm², which rounds up to 8 AWG.
Q: How far can you run 10 gauge wire on a 220V circuit?
A: On a 220 V circuit, 10 AWG copper (5.26 mm²) keeps a 30 A load inside the 3 percent voltage-drop target out to about 34 m one-way. A 20 A load on the same cable stays inside the same target out to about 52 m. Beyond those distances, stepping up to 8 AWG or 6 AWG brings the voltage drop back under 3 percent.
Q: Can I use aluminum wire for 220V?
A: Yes. Aluminum is common on long 220 V feeders because it costs less per metre than copper. Because aluminum has about 68 percent of copper's conductivity, you typically step up two AWG sizes to match the same voltage drop.
Q: What is the formula for wire size by voltage drop?
A: Wire cross-section by voltage drop is A = (2 x I x rho x L) / (V x dropFraction). The 2 covers the out-and-back loop, I is load current, rho is conductor resistivity, L is one-way distance, V is supply voltage, and dropFraction is the allowed drop as a decimal.