24V Wire Size Calculator

Your details

The continuous current the wire must carry, in amperes.
A
One-way cable length from source to load (not round-trip). The calculator doubles it internally for a DC circuit.
ft
Typical guidance: 3% for most 24V loads, 2% for sensitive electronics and battery charging, up to 5% for motors and lighting.
%
Expected wire operating temperature. Higher temperature increases resistance. Use 60 C for standard TW/THWN in conduit, 75 C or 90 C for high-temp insulation.
C
NEC ampacity tables are tied to insulation temperature rating. 75 C is the most common commercial standard.
Recommended wire gaugeMarginal
8 AWG

Smallest AWG copper gauge that meets both voltage-drop and ampacity requirements

Actual voltage drop0.727V
Voltage drop (%)3.03%
Power loss in wire14.54W
System efficiency96.97%
Total wire resistance0.0363ohm
Cross-section area8.37mm2
Voltage at load23.273V
3.03 %
Excellent (<2%)<2Acceptable (2-3%)2-3Marginal (3-5%)3-5Excessive (>5%)5+

Use 8 AWG copper wire for this 24V run.

  • At 8 AWG, actual voltage drop is 0.727 V (3.03%), well within your 3% limit.
  • The wire dissipates 14.54 W as heat - factor this into your enclosure thermal design.
  • System efficiency: 96.97% of supply power reaches the load.
  • NEC ampacity for 8 AWG at 75 C is 50 A - you have a 30 A safety margin.

Next stepConsider going one gauge larger to reduce heat and drop, especially for long continuous-duty runs.

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