Loading...
24/7 Emergency Electric Service Available
1-833-948-1603Loading...
Enter your circuit details to determine the correct wire size
Distance from panel to load
Choosing the wrong wire size isn't just a code violation—it's a fire hazard. Undersized wires overheat when carrying too much current, and overheated wires start fires. It's that simple, and that serious.
Our wire size calculator helps you determine the correct wire gauge for your electrical circuit. Whether you're running a new outlet, installing a sub-panel, or wiring a workshop, you need to match the wire size to the load and distance.
This isn't optional or a matter of preference. Electrical codes specify minimum wire sizes for a reason, and your local inspector will catch violations. More importantly, proper wire sizing protects your home and family from electrical fires.
Wire sizing depends on several electrical and physical factors:
Undersized wire overheats, damages insulation, and causes fires. Proper sizing prevents this completely.
Electrical inspectors check wire sizes. Wrong sizes mean failed inspections and mandatory corrections.
Properly sized circuits don't trip breakers under normal use or experience voltage drop that dims lights and affects equipment.
Sizing slightly larger than minimum can accommodate future changes without rewiring.
Mistake: Using household wire for long outdoor runs
Solution: Outdoor and underground runs have different requirements. A 12-gauge wire fine for a short indoor run might cause excessive voltage drop on a 100-foot outdoor run.
Mistake: Ignoring the breaker rating
Solution: Wire size must match the breaker. You can't put 14-gauge wire on a 20-amp breaker, even if the load is small. The wire must handle the breaker's maximum capacity.
Mistake: Mixing wire sizes in a circuit
Solution: All wire in a circuit must be rated for the breaker size. You can't use 14-gauge 'because this section carries less load'—the whole circuit must be sized for the maximum.
Mistake: Forgetting about conduit fill
Solution: Wires in conduit generate more heat than open-air wires. Too many wires in a conduit may require upsizing.
Electrical work is inherently dangerous. Call a pro when:
For a 20-amp circuit, you need at minimum 12-gauge copper wire (or 10-gauge aluminum). For longer runs (over 50 feet), you may need 10-gauge copper to prevent excessive voltage drop.
Electricity loses voltage as it travels through wire—this is called voltage drop. Longer distances mean more drop. If voltage drops too much (over 3%), equipment doesn't work properly and energy is wasted as heat.
Yes, larger wire is always safe. The only downsides are cost and that it's harder to work with. Many electricians size one gauge larger than minimum as a safety margin and for future flexibility.
Aluminum is cheaper but requires larger sizes for the same amperage (it conducts less well), needs special connectors, and isn't allowed for most branch circuits. It's mainly used for large feeder cables and service entrances.