Looking for a fast and accurate DC wire size calculator for your next electrical project? This free tool helps you determine the minimum required cable thickness in mm², based on voltage drop, wire length, and either power, voltage, or current.
It’s ideal for DC applications like:
- solar panel systems
- e-bike motors and controllers
- battery banks
- low-voltage LED setups
- mobile power systems
You can also convert the result into AWG or SWG for international compatibility.
Why use this wire size calculator?
- Calculates wire size from voltage drop, cable length, power, voltage or current
- Works with both copper and aluminum wires
- Output in square millimeters (mm²) with optional AWG and SWG
- Designed for DC circuits like e-bikes, solar power and 12V/24V systems
- Ensures safe and efficient wire sizing
- Advises you to round up to the next standard wire size
- Fully browser-based — no login, no downloads, no clutter
🔧 Wire Size Calculator
Frequently Asked Questions (FAQ)
What does this wire size calculator actually calculate?
This calculator determines the minimum wire cross-sectional area in mm² based on length, voltage drop, and electrical load. It can also convert the result to AWG and SWG formats.
Can I use this tool for AC circuits?
No. This tool is designed specifically for DC wiring. For AC installations, you should consult national electrical codes or a certified electrician.
Is this suitable for e-bikes and 12V systems?
Absolutely. It’s ideal for calculating cable size for e-bikes, 12V/24V battery systems, inverters, and off-grid solar setups.
What values do I need to enter?
You must provide:
- The total cable length
- Acceptable voltage drop (in %)
- At least two of these three: power (W), voltage (V), current (A)
What does “minimum wire size” mean?
The result is the bare minimum required to keep voltage drop within limits. For safety and compatibility, always round up to the next available wire size.
What is the difference between mm², AWG and SWG?
- mm² is the metric standard based on cross-sectional area
- AWG is the American Wire Gauge, based on wire diameter
- SWG is the British equivalent of AWGThis tool supports all three for comparison.