Voltage Drop Calculator

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voltage drop 24v 10 meters 14 awg

Voltage drop at 12 V and 24 V with AWG wire (10 meters, 14 AWG)

The tool opens in DC with AWG 14. Pick the AWG gauge, the voltage and the length: the conversion to mm² appears beside it, and the table compares AWG 24 to 4/0.

Low voltage loses more, in percent

The drop in volts depends only on the current, the length and the cross-section, but the percentage divides by the voltage. The same 0.83 V is 0.4 % of 220 V and almost 7 % of 12 V. That is why 12 V and 24 V circuits call for thicker wire or short runs. In DC the factor is 2, for out and back: 8 A, 10 m and AWG 14 (2.081 mm²) give ΔV = 2 × 8 × 10 × 0.0172 ÷ 2.081 = 1.32 V, or 5.51 % of 24 V.
The AWG to mm² conversion uses the diameter d = 0.127 mm × 92^((36 − n) ÷ 39) and the area of the circle. AWG 14 is 2.08 mm², AWG 10 is 5.26 mm² and AWG 18 is 0.823 mm². These are solid-wire values; stranded wire of the same gauge has a slightly smaller effective area. Moving from AWG 14 to AWG 10 cuts the drop of the 24 V example from 1.32 V to 0.52 V, or 2.18 %.
To find the gauge for the drop criterion, the tool calculates the minimum size: 10 A, 5 m and a 3 % limit at 12 V call for 4.78 mm², and the next AWG with that area is 10. At 24 V, 8 A and 10 m, the 3 % limit calls for 3.82 mm². The calculation considers the drop only; the current capacity of the wire and the circuit protection are another criterion and are not checked here.

Checked examples

AWG 14, 10 A, 5 m, 12 V

Input: AWG 14, 10 A, 5 m, 12 V → ΔV
Expected output: 0.83 V (6.89 %)

2 × 10 × 5 × 0.0172 ÷ 2.081.

AWG 14, 8 A, 10 m, 24 V

Input: AWG 14, 8 A, 10 m, 24 V → ΔV
Expected output: 1.32 V (5.51 %)

2 × 8 × 10 × 0.0172 ÷ 2.081.

AWG 10, 8 A, 10 m, 24 V

Input: AWG 10, 8 A, 10 m, 24 V → ΔV
Expected output: 0.52 V (2.18 %)

2 × 8 × 10 × 0.0172 ÷ 5.261.

AWG 18, 5 A, 3 m, 12 V

Input: AWG 18, 5 A, 3 m, 12 V → ΔV
Expected output: 0.63 V (5.22 %)

2 × 5 × 3 × 0.0172 ÷ 0.823.

Minimum size, 12 V, 10 A, 5 m, 3 %

Input: 12 V, 10 A, 5 m, 3 % → S
Expected output: 4.78 mm²

2 × 10 × 5 × 0.0172 ÷ (0.03 × 12).

Minimum size, 24 V, 8 A, 10 m, 3 %

Input: 24 V, 8 A, 10 m, 3 % → S
Expected output: 3.82 mm²

2 × 8 × 10 × 0.0172 ÷ (0.03 × 24).

Full tool FAQ

How do I calculate voltage drop in a cable?

In DC or single-phase, ΔV = 2 × L × I × ρ ÷ S, with L in meters, I in amps, ρ in Ω·mm²/m and S in mm². For copper at 20 °C, 20 m, 25 A and 6 mm²: 2 × 20 × 25 × 0.0172 ÷ 6 = 2.87 V. At 220 V that is 1.30 %.

How is three-phase voltage drop calculated?

What is an acceptable voltage drop limit?

Is the length one-way or round trip?

Why does the drop increase with temperature?

How do I convert AWG to mm²?

Aluminum or copper: how much does the drop change?

Can I use this calculator to choose the wire gauge?

How much power is lost in the cable?

Does the tool consider cable reactance?

Frequently asked questions

How do I convert AWG to mm²?

d = 0.127 × 92^((36 − n) ÷ 39) mm and area = π ÷ 4 × d². AWG 14 is 2.08 mm² and AWG 10 is 5.26 mm².

What drop is acceptable at 12 V?

It depends on the device and the design. Since 1 V is already 8.3 % of 12 V, many people adopt tighter limits at low voltage; the limit is your own field in the tool.

Why does LED or car wiring heat up and lose brightness?

Wire resistance creates a voltage drop and dissipates 2 × I² × R as heat. More length or less cross-section increases both.

Next steps

ΔV (V)	ΔV (%)	Voltage at the load	Cable loss	Meets
34.4	15.64	185.6	860	✗
22.93	10.42	197.1	573.3	✗
17.2	7.818	202.8	430	✗
11.47	5.212	208.5	286.7	✗
6.88	3.127	213.1	172	✓
4.3	1.955	215.7	107.5	✓
2.867	1.303	217.1	71.67	✓
1.72	0.7818	218.3	43	✓
1.075	0.4886	218.9	26.87	✓
0.688	0.3127	219.3	17.2	✓
0.4914	0.2234	219.5	12.29	✓
0.344	0.1564	219.7	8.6	✓
0.2457	0.1117	219.8	6.143	✓
0.1811	0.0823	219.8	4.526	✓
0.1433	0.06515	219.9	3.583	✓
0.1147	0.05212	219.9	2.867	✓
0.09297	0.04226	219.9	2.324	✓
0.07167	0.03258	219.9	1.792	✓
0.05733	0.02606	219.9	1.433	✓

mm²

ΔV (V)

ΔV (%)

Voltage at the load

Cable loss

Meets

34.4

15.64

185.6

860

✗

22.93

10.42

197.1

573.3

✗

17.2

7.818

202.8

430

✗

11.47

5.212

208.5

286.7

✗

6.88

3.127

213.1

172

✓

4.3

1.955

215.7

107.5

✓

2.867

1.303

217.1

71.67

✓

1.72

0.7818

218.3

✓

1.075

0.4886

218.9

26.87

✓

0.688

0.3127

219.3

17.2

✓

0.4914

0.2234

219.5

12.29

✓

0.344

0.1564

219.7

8.6

✓

0.2457

0.1117

219.8

6.143

✓

0.1811

0.0823

219.8

4.526

✓

0.1433

0.06515

219.9

3.583

✓

0.1147

0.05212

219.9

2.867

✓

0.09297

0.04226

219.9

2.324

✓

0.07167

0.03258

219.9

1.792

✓

0.05733

0.02606

219.9

1.433

✓

Low voltage loses more, in percent

The drop in volts depends only on the current, the length and the cross-section, but the percentage divides by the voltage. The same 0.83 V is 0.4 % of 220 V and almost 7 % of 12 V. That is why 12 V and 24 V circuits call for thicker wire or short runs. In DC the factor is 2, for out and back: 8 A, 10 m and AWG 14 (2.081 mm²) give ΔV = 2 × 8 × 10 × 0.0172 ÷ 2.081 = 1.32 V, or 5.51 % of 24 V.

The AWG to mm² conversion uses the diameter d = 0.127 mm × 92^((36 − n) ÷ 39) and the area of the circle. AWG 14 is 2.08 mm², AWG 10 is 5.26 mm² and AWG 18 is 0.823 mm². These are solid-wire values; stranded wire of the same gauge has a slightly smaller effective area. Moving from AWG 14 to AWG 10 cuts the drop of the 24 V example from 1.32 V to 0.52 V, or 2.18 %.

To find the gauge for the drop criterion, the tool calculates the minimum size: 10 A, 5 m and a 3 % limit at 12 V call for 4.78 mm², and the next AWG with that area is 10. At 24 V, 8 A and 10 m, the 3 % limit calls for 3.82 mm². The calculation considers the drop only; the current capacity of the wire and the circuit protection are another criterion and are not checked here.

Checked examples

AWG 14, 10 A, 5 m, 12 V

Input: AWG 14, 10 A, 5 m, 12 V → ΔV
Expected output: 0.83 V (6.89 %)

2 × 10 × 5 × 0.0172 ÷ 2.081.

AWG 14, 8 A, 10 m, 24 V

Input: AWG 14, 8 A, 10 m, 24 V → ΔV
Expected output: 1.32 V (5.51 %)

2 × 8 × 10 × 0.0172 ÷ 2.081.

AWG 10, 8 A, 10 m, 24 V

Input: AWG 10, 8 A, 10 m, 24 V → ΔV
Expected output: 0.52 V (2.18 %)

2 × 8 × 10 × 0.0172 ÷ 5.261.

AWG 18, 5 A, 3 m, 12 V

Input: AWG 18, 5 A, 3 m, 12 V → ΔV
Expected output: 0.63 V (5.22 %)

2 × 5 × 3 × 0.0172 ÷ 0.823.

Minimum size, 12 V, 10 A, 5 m, 3 %

Input: 12 V, 10 A, 5 m, 3 % → S
Expected output: 4.78 mm²

2 × 10 × 5 × 0.0172 ÷ (0.03 × 12).

Minimum size, 24 V, 8 A, 10 m, 3 %

Input: 24 V, 8 A, 10 m, 3 % → S
Expected output: 3.82 mm²

2 × 8 × 10 × 0.0172 ÷ (0.03 × 24).

Full tool FAQ

How do I calculate voltage drop in a cable?

How is three-phase voltage drop calculated?

What is an acceptable voltage drop limit?

Is the length one-way or round trip?

Why does the drop increase with temperature?

How do I convert AWG to mm²?

Aluminum or copper: how much does the drop change?

Can I use this calculator to choose the wire gauge?

How much power is lost in the cable?

Does the tool consider cable reactance?

Frequently asked questions

How do I convert AWG to mm²?

d = 0.127 × 92^((36 − n) ÷ 39) mm and area = π ÷ 4 × d². AWG 14 is 2.08 mm² and AWG 10 is 5.26 mm².

What drop is acceptable at 12 V?

It depends on the device and the design. Since 1 V is already 8.3 % of 12 V, many people adopt tighter limits at low voltage; the limit is your own field in the tool.

Why does LED or car wiring heat up and lose brightness?

Wire resistance creates a voltage drop and dissipates 2 × I² × R as heat. More length or less cross-section increases both.