WireSizer - DC Voltage Drop

WireSizer is the fast, accurate, and easy-to-use DC wire size calculator for choosing the correct wire gauge every time.

Simply select your DC voltage, current, and total circuit length with flips of your finger. No keyboard required. WireSizer instantly calculates the correct wire gauge for the Voltage Drop percentage you need.

WireSizer is ideal for:
• Boats and marine electrical systems
• RVs, trucks, and cars
• Radios and electronics
• Solar power and battery-based DC systems
• Any low-voltage DC system up to 60 VDC

Suitable for both professionals and DIY users.

WireSizer automatically calculates the minimum wire size required for your circuit (assuming copper wire), taking Voltage Drop into account for installation and temperature conditions. Results are checked against current-carrying capacity (ampacity) limits to prevent using unsafe undersized wire.

Supported values:
• Voltage up to 60 VDC
• Current up to 500 amps
• Total circuit length up to 600 feet or 200 meters
• Voltage Drop 1 to 20 percent
• AWG wire 18 gauge to 4/0, plus 250 & 300 kcmil
• SAE wire 18 gauge to 4/0
• Metric wire 0.75 mm² to 150 mm²

WireSizer allows you to fine-tune calculations based on real-world installation conditions:
• Engine compartment or other high-temperature environments
• Sheathed, bundled, or conduit-run wire
• Wire insulation ratings from 60°C to 200°C

WireSizer also includes a Materials List so you can record and review all of your wire selections in one place.

WireSizer calculates DC wire sizes in accordance with ABYC E-11 (July 2025). For typical low-voltage DC circuits, results generally correspond with ISO 13297:2020.

Results are a design aid; final wire selection and installation compliance remain the installer's responsibility.

Number and decimal formatting will follow your device's regional and language settings.

WireSizer works without an internet connection and contains no ads.

Designed exclusively for DC circuits - not for use with AC circuits.

Results are a design aid. Final wire selection and installation compliance remain the installer's responsibility.

WireSizer will cost you less than the wire scraps you probably throw away at the end of the day.