⚡ 24V DC Voltage Drop Calculator
Calculate wire voltage drop, end voltage, and percent loss for any 24V DC circuit
| Wire Length | 12 AWG | 14 AWG | 16 AWG | 18 AWG | % Drop (12 AWG) |
|---|---|---|---|---|---|
| 25 ft (7.6m) | 0.40V | 0.64V | 1.02V | 1.60V | 1.7% |
| 50 ft (15.2m) | 0.81V | 1.29V | 2.05V | 3.19V | 3.4% |
| 75 ft (22.9m) | 1.21V | 1.93V | 3.07V | 4.79V | 5.1% |
| 100 ft (30.5m) | 1.62V | 2.58V | 4.09V | 6.39V | 6.7% |
| 150 ft (45.7m) | 2.43V | 3.86V | 6.14V | 9.58V | 10.1% |
| 200 ft (61.0m) | 3.24V | 5.15V | 8.19V | 12.77V | 13.5% |
| AWG | Max Amps (chassis) | Ω/1000ft (Cu) | Ω/1000ft (Al) | Ω/km (Cu) | mm² approx. |
|---|---|---|---|---|---|
| 8 AWG | 40A | 0.641 | 1.053 | 2.103 | 8.37 |
| 10 AWG | 30A | 1.018 | 1.673 | 3.340 | 5.26 |
| 12 AWG | 20A | 1.619 | 2.660 | 5.315 | 3.31 |
| 14 AWG | 15A | 2.575 | 4.231 | 8.449 | 2.08 |
| 16 AWG | 13A | 4.094 | 6.727 | 13.43 | 1.31 |
| 18 AWG | 10A | 6.385 | 10.49 | 20.95 | 0.823 |
| 20 AWG | 5A | 10.15 | 16.68 | 33.29 | 0.519 |
| 22 AWG | 3A | 16.14 | 26.52 | 52.95 | 0.326 |
| 24 AWG | 2A | 25.67 | 42.18 | 84.19 | 0.205 |
| Cross-section | Ω/km (Cu) | Ω/km (Al) | Max Amps | AWG approx. |
|---|---|---|---|---|
| 0.25 mm² | 72.0 | 118.5 | 2A | ~24 AWG |
| 0.50 mm² | 36.0 | 59.2 | 3A | ~22 AWG |
| 0.75 mm² | 24.0 | 39.5 | 6A | ~20 AWG |
| 1.0 mm² | 18.0 | 29.6 | 10A | ~18 AWG |
| 1.5 mm² | 12.1 | 19.8 | 13A | ~16 AWG |
| 2.5 mm² | 7.41 | 12.2 | 18A | ~14 AWG |
| 4.0 mm² | 4.61 | 7.58 | 25A | ~12 AWG |
| 6.0 mm² | 3.08 | 5.06 | 32A | ~10 AWG |
| 10 mm² | 1.83 | 3.01 | 43A | ~8 AWG |
Even so, the Voltage drop in 24 V dc-systems is commonly underestimated seriously. Here is the cause: if you lose 2,4 V from 24 V supply, then you lose 10 % of your energy. And what happens with that same 2,4 V drop from 240 V ac supply?
It only reaches 1 %. The main trouble does not lie in that it is dc, rather, it comes from the low Voltage itself that makes everything much more sensitive.
Voltage Drop in 12 V and 24 V DC Systems
Voltage drops happen over distance, when current flows through cable. The resistance of the wire, together with the amount of flow that you pull, decide the drop. The precise calculation is the square of the current times the resistance of the wire.
Simply said, one starts with the resistance for one length of the cable, later multiply by the real distance, and do not forget to double it, because the flow must go forward and back. It seems easy after a bit of thinking.
Systems with low Voltages (for instance 12 V or 24 V), are more exposed to those drops than one believes. If you lose only 1 V in a 12 V system, that matches to 8,33 % of your entering Voltage. The same 1 V drop in a 230 V circuit barely shows as 0,43 %.
This sensitivity explains why the diameter of your cable, its length and even the quality matters this much.
Here something unlikely: dc indeed handles Voltage drops batter compared to ac in some ways. Dc only struggles against resistance, while ac must face resistance together with reactance. Underground ac lines suffer extra drops because of linear inductance and parasitic capacitance, that dc does not meet.
Even so, dc got its name because of long-range drops, and that exactly causes energy companies to stay with ac for broadcasting.
The Voltage drop depends entirely on the resistance of the cable, nothing more. If you pull 1 amp through it, you lose 1 volt over that distance. Pulling 2 amps, the drop jumps to 2 Voltage.
Reducing those resistance drops is a good way forward. In a 24 V dc system with 10 % tolerance for function or loss, you require minimal Voltage of 21,6 V, so the maximum allowed drop stays at 2,4 V from that 24 V supply. For instance, 2000 feet of 16 gauge wire has around 8 ohms of resistance.
Switching from 12 V to 24 V in camping or outdoor systems, you can push doubly more watts threw same cable. If you keep the same wire but pass to 24 V, the Voltage drop halves; because the flow also halves. What is the catch?
Finding 24 V dc devices is not entirely easy. And if you use 24 V only to later convert down to 12 V for almost everything, that conversion removes the biggest part of your gains. Some favor 24 V inverters, because the lower flow makes a 2 V drop less important as apercentage of the whole Voltage.
Calculators for Voltage drop help to remove guessing from the planning. Some rely on NEC tables about resistance and reactance, while others estimate by lengths of wire gauges. They work for solar pv systems, battery banks, automotive cables and other low Voltage uses at 12 V, 24 V or 48 V.
