Wire Gauge Sizing Calculator (AWG)
Find the minimum recommended electrical wire gauge (AWG) based on amperage, circuit voltage, distance, and maximum allowable voltage drop.
Enter Your Dimensions
US • ftHow We Calculated This
• Always verify circuit breaker rating does not exceed the thermal ampacity limit of the chosen wire size.
Formula & Volumetric Method
Required Circular Mils = (2 × 12.9 × Amps × Distance) ÷ Allowed Voltage Drop. Selected wire must meet or exceed required CM.
Calculations are performed strictly using standard civil engineering constants. Volumetric outputs are normalized to true compaction rates, ensuring purchased quantities match jobsite yields.
Jobsite Engineering Guidelines
- 3% max drop is recommended by NEC for branch circuits.
- Copper is standard for residential interior branch circuits.
Frequently Asked Questions
How accurate is the Wire Gauge Sizing Calculator (AWG) for ordering materials?
Our calculations match standard store packaging sizes in the US, Canada, UK, and Australia. We include a safety waste buffer (default 8% to 12%) so you do not run short due to uneven ground or spillage.
Why should I add extra for waste when ordering?
Uneven ground, cutting scrap, and leftover mix in the wheelbarrow or mixer drum consume an extra 5% to 15% of material. Ordering only the exact measurement usually leaves you short, which can lead to expensive extra delivery fees.
Does this calculator support both Imperial and Metric units?
Yes. You can switch between US Customary (feet, inches, cubic yards, pounds), Canadian units, UK metric, and Australian standards using the region selector in the header or the unit dropdown on each input.