Find the Right Wire Size for Any Project
A free browser-based wire gauge calculator that recommends the correct AWG wire size based on current, distance, and maximum allowable voltage drop. Supports copper and aluminum wires, includes AWG-to-mm² conversion, ampacity reference table, and practical presets for LED strips, outlets, EV chargers, and solar panels.
Select the optimal wire size based on current, distance, and voltage drop
Features
How to Calculate Wire Gauge
- Enter current and distance. Set the load current in amps, one-way wire distance in meters or feet, and system voltage.
- Set voltage drop limit. Choose the maximum acceptable voltage drop (typically 3% for branch circuits, 5% for feeders).
- Read the recommendation. See the recommended AWG gauge, cross-section in mm², actual voltage drop, and power loss in the wire.
FAQ
What is AWG?
American Wire Gauge — a standardized system for wire diameters. Lower AWG = thicker wire. AWG 10 ≈ 5.26 mm², AWG 14 ≈ 2.08 mm². Used primarily in North America.
How is voltage drop calculated?
Vdrop = 2 × I × R × L, where I is current, R is resistance per meter, L is one-way distance. Factor of 2 accounts for the round trip (supply + return wire).
What voltage drop is acceptable?
NEC recommends max 3% for branch circuits and 5% total (feeder + branch). For 12V DC systems, even 3% (0.36V) can affect LED brightness, so use thicker wire.
Copper vs aluminum — which to use?
Copper has 61% lower resistance and is standard for most wiring. Aluminum is cheaper and lighter but requires larger gauges and special connectors to prevent corrosion.
What is ampacity?
The maximum current a wire can carry continuously without exceeding its temperature rating. Depends on wire gauge, insulation type, ambient temperature, and installation method.
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