What Is the Voltage Drop for 12 AWG at 19A and 25 Feet?

12 AWG at 19A and 25 feet: 1.88V drop (1.57% on 120V), computed on the single-phase / DC basis. Every conductor has resistance, and longer runs at higher currents drop more voltage. Use this calculation to check whether your run clears the 3% branch-circuit drop target before pulling wire.

12 AWG, 19A, 25ft · single-phase / DC

1.88 V drop (1.57% on 120V)

On 120V circuit1.57%

On 240V circuit0.7838%

Circuit basis: This uses the single-phase / DC round-trip formula (factor of 2) for the voltage drop across the two circuit conductors. For a three-phase line-to-line run use the three-phase version of the page (append ?type=3ph). Switch to the three-phase version →

Gauge

12 AWG

Amps

Feet

Drop @ 120V

1.88V (1.57%)

Assumes a 120V source on a single-phase / DC circuit. Use the circuit-basis link above to switch between single-phase/DC and three-phase.

Voltage Drop Formula (single-phase / DC)

V_drop = (2 × L × I × R) ÷ 1000

(2 × 25 × 19 × 1.98) ÷ 1000 = 1.88 V

DC and single-phase AC use the round-trip factor of 2. Current travels out to the load on one conductor and returns on another.

For a three-phase circuit at the same amps and distance, see the three-phase version (uses √3 instead of 2, so the drop is about 13.4% lower).

Percentage

%VD = (V_drop ÷ V_source) × 100

On 120V: (1.88 ÷ 120) × 100 = 1.57%

On 240V: (1.88 ÷ 240) × 100 = 0.7838%

How This Estimate Changes with Run Length and Gauge

Gauge Check

12 AWG clears the 3% drop target at these inputs. A smaller conductor may also meet it with less margin. See the minimum gauge for this load and distance.

Impact of Distance

Voltage drop is proportional to distance. Here is 12 AWG at 19A at different distances:

Distance	Drop (V)	% on 120V	% on 240V	NEC (120V)
25ft	1.88V	1.57%	0.7838%	OK
50ft	3.76V	3.14%	1.57%	Caution
75ft	5.64V	4.7%	2.35%	Caution
100ft	7.52V	6.27%	3.14%	Past 5%
150ft	11.29V	9.41%	4.7%	Past 5%
200ft	15.05V	12.54%	6.27%	Past 5%
300ft	22.57V	18.81%	9.41%	Past 5%

Same Run, Different Wire Gauges

How does wire gauge affect voltage drop for 19A at 25 feet on 120V single-phase / DC? Only gauges whose branch-circuit OCP cap is at or above the 19A load are listed, since thinner gauges would fail the ampacity check before drop even matters.

Gauge	Drop (V)	% on 120V	% on 240V	3% Target (120V)
12 AWG	1.88V	1.57%	0.7838%	OK
10 AWG	1.18V	0.9817%	0.4908%	OK
8 AWG	0.7391V	0.6159%	0.308%	OK
6 AWG	0.4665V	0.3887%	0.1944%	OK
4 AWG	0.2926V	0.2438%	0.1219%	OK
3 AWG	0.2328V	0.194%	0.097%	OK

Related Calculations

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Frequently Asked Questions

What is the voltage drop for 12 AWG at 19A and 25ft?expand_more

12 AWG carrying 19A over 25ft has a 1.88V drop (1.57% on 120V). Reference: 0.7838% on 240V.

Why does distance affect voltage drop?expand_more

Voltage drop is proportional to distance. The formula multiplies by 2 × the distance (out and back). Doubling the run doubles the drop.

What wire gauge should I use instead of 12 AWG for this run?expand_more

12 AWG already sits within the 3% branch-circuit drop target at these inputs (1.57% on 120V). Going to a larger gauge is only useful if you want more headroom for future load growth, longer runs, or tighter drop targets like the 5% feeder+branch total recommendation used in sensitive or motor-heavy installations.

Does wire material affect voltage drop?expand_more

Yes. Aluminum has roughly 1.3 to 1.4 times the resistance of copper at the NEC Chapter 9 Table 8 75°C reference temperature, so for the same voltage drop an aluminum conductor is typically one to two gauges larger than copper. The exact gap depends on whether ampacity or voltage drop is binding, and the install still needs anti-oxidant compound and aluminum-rated lugs.

Does 12 AWG meet the 3% drop target at 19A and 25ft on 120V?expand_more

On 120V, this run sits at 1.57%, which is within the 3% branch and 5% feeder+branch total drop targets. NEC 210.19(A) Informational Note 4 cites 3% for branch circuits and 5% for total feeder+branch drop as performance recommendations, not hard code requirements.

This calculator provides estimates for reference purposes only. Always consult a licensed electrician and verify compliance with the National Electrical Code (NEC) and local electrical codes before performing any electrical work.