The two most common residential wire sizes compared. 12 AWG is rated for 20-amp circuits and required for kitchen countertop and bathroom outlets. 14 AWG is rated for 15-amp circuits and typically used for lighting and general-purpose bedroom or living room outlets. The key difference comes down to ampacity, NEC overcurrent protection limits, and voltage drop performance.
Diameter: 2.053 mm (0.0808 in)
Cross-section: 3.31 mm²
Max breaker: 20A (NEC 240.4(D))
Resistance: 1.588 Ω/1000 ft
Common in: 20A outlets, kitchen circuits, garage, appliances
Diameter: 1.628 mm (0.0641 in)
Cross-section: 2.08 mm²
Max breaker: 15A (NEC 240.4(D))
Resistance: 2.525 Ω/1000 ft
Common in: 15A lighting circuits, bedrooms, general-purpose
| Property | 12 AWG | 14 AWG |
|---|---|---|
| AWG Size | 12 | 14 |
| Diameter | 2.053 mm (0.0808 in) | 1.628 mm (0.0641 in) |
| Cross-section | 3.31 mm² | 2.08 mm² |
| Ampacity (60°C) | 20A | 15A |
| Ampacity (75°C) | 25A | 20A |
| Ampacity (90°C) | 30A | 25A |
| Max Overcurrent (NEC 240.4(D)) | 20A | 15A |
| Resistance per 1000 ft | 1.588 Ω | 2.525 Ω |
| Typical breaker | 20A | 15A |
| NEC cable type | NM-B (Romex) 12/2, 12/3 | NM-B (Romex) 14/2, 14/3 |
| Common applications | Kitchen outlets, bathrooms, garages, workshops, outdoor receptacles | Lighting circuits, bedrooms, living rooms, general-purpose outlets |
| Cost (relative) | Higher (~25–30% more than 14 AWG) | Lower (baseline) |
Voltage drop calculated using VD = 2 × I × R × L ÷ 1000. 14 AWG at rated 15A; 12 AWG at rated 20A.
| One-Way Distance | 14 AWG @ 15A | 12 AWG @ 20A | ||
|---|---|---|---|---|
| Volts | % Drop | Volts | % Drop | |
| 25 ft | 1.89 V | 1.6% | 1.59 V | 1.3% |
| 50 ft | 3.79 V | 3.2% | 3.18 V | 2.6% |
| 75 ft | 5.68 V | 4.7% | 4.76 V | 4.0% |
| 100 ft | 7.58 V | 6.3% | 6.35 V | 5.3% |
| 150 ft | 11.36 V | 9.5% | 9.53 V | 7.9% |
Cells highlighted in red exceed the NEC-recommended 3% voltage drop for branch circuits. Consider upsizing wire or shortening runs.
NEC Requirements: NEC 240.4(D) mandates maximum overcurrent protection of 15A for 14 AWG and 20A for 12 AWG copper conductors. NEC 210.11 requires 20A circuits for kitchen countertop and bathroom receptacles. You cannot use 14 AWG wire on a 20A breaker — doing so is a code violation and a fire hazard.
No. NEC 240.4(D) limits 14 AWG to 15A overcurrent protection. Using 14 AWG on a 20A breaker is a code violation and fire hazard. The wire could overheat before the breaker trips, potentially causing a fire inside the wall.
Not necessarily. While 14 AWG is code-compliant for 15A lighting circuits, 12 AWG provides a safety margin, reduces voltage drop on longer runs, and allows future circuit upgrades to 20A without rewiring. The added cost is typically modest compared to total project cost.
At 100 feet on a 15A load, 14 AWG drops about 3.8% while 12 AWG drops about 2.4%. For runs over 50 feet, 12 AWG helps stay within the NEC-recommended 3% maximum voltage drop for branch circuits.
NEC 210.11(C)(1) requires at least two 20A small-appliance branch circuits for kitchen countertop receptacles, which means 12 AWG minimum. 14 AWG cannot be used for these circuits regardless of the load.