WireSizer 4+

DC Voltage Drop Calculator

Juggernaut Technology, Inc.

Designed for iPad

    • 4.4 • 193 Ratings
    • $4.99



The simple, intuitive, and fun way to accurately determine which size of wire is right for your job. Perfect for most DC applications up to 60 Volts DC!

WireSizer is the simple and intuitive way to calculate the wire gauge needed for a desired voltage drop for most common DC applications up to 60 volts. It is great for doing quick calculations when updating wiring on boats, RVs, trucks, cars, radios, or other "low voltage" DC applications for both do-it-yourselfers and professionals.

Others agree!

"This app is a joy to use! ...you'll be able to get the right wire gauge to use every time. Nice." - Cruising World Blog (11/27/2012)

"It is a must have for your electrical toolbox." - i-marineapps (2/9/2013)

To find your proper wire, simply select your DC voltage, your current, and the length of your circuit with simple flicks of your finger. No keyboard input needed! WireSizer will automatically calculate the minimum wire size for different percentages of voltage drop under normal or "engine compartment" operating conditions using copper wire. Wire gauge recommendations include commonly available sizes in AWG, SAE and ISO/Metric.

Using properly sized wire is important. Undersized wire can lead to equipment malfunction or failure, and oversized wire will add to cost and can be harder to work with. And unlike "online" wire gauge calculators, WireSizer will work wherever or whenever you need it.

WireSizer allows you to select voltages up to 60 VDC, current up to 500 amps, and total circuit length in feet or meters up to 600 feet (or 200 meters).

Results calculated are for voltage drops between 1 and 20 percent (which you can "flip" through to find the one which is best for your purpose), and wire sizes between 4/0 and 18 gauge AWG and SAE, and 0.75 to 92 mm.

WireSizer will also let you select whether the wire is going to run through an engine compartment or a similarly "hot" environment, is sheathed, bundled, or in conduit, and select the wires insulation rating (60C, 75C, 80C, 90C, 105C, 125C, 200C) to fine tune your results.

And finally, the voltage drop calculation results are compared with the safe current carrying capacity (or "ampacity") of the wire, to make sure the wire suggested is suitable.

And for your convenience, WireSizer also includes a "Materials List" for you to record all of your wire selections.

WireSizer gauge calculation results meet ABYC E11 specifications (standard requirement for boats, excellent guidelines for other uses) provided you have clean connections, and are using good quality wire. ABYC specifications meet or exceed NEC where applicable, and correspond to ISO/FDIS.


If you have any questions (or complaints!), please email us.

Ad free, and will cost less than the wire scraps you probably throw away at the end of the day.

What’s New

Version 3.25

+ Improved layout on larger iPhones!

If you have any questions, problems, or comments, please contact us at support@WireSizer.com!

Ratings and Reviews

4.4 out of 5
193 Ratings

193 Ratings

Cazabuilds ,

Very helpful, limited to 50VDC

I use this app all the time! Would use it even more if it could support higher voltages. I’d like to see at least 150vdc, and 240vac. Thanks for the useful tool!

Developer Response ,

The latest version now allows voltage up to 60 volts DC. 
Calculating wire sizes for higher voltages requires taking into account some additional factors to do properly (which many voltage drop calculators neglect). We are planning on investigating the feasibility of this in the future. Thanks for the review!

24Spokes ,

Easy to use and accurate

I am a Marine Engineer and I use this app at my desk and in the field to run “how to” calculations to determine the wire size required for a particular voltage, load current and circuit run. The spinner wheels make it very easy to enter the data and the drill down that is available when the results tapped is an excellent bonus. My favorite wire sizing app.

solar installs ,

Works well, some limitations

Overall it’s a very good tool. I use it to size DC wires runs for solar. I have verified accuracy with manual calculations of voltage drop. It’s limited to 50vdc maximum so works well for up to 48vdc battery banks but can’t use it for solar panels in series as voltage exceed 50v limit.

Developer Response ,

The latest version of WireSizer now supports up to 60 VDC. Suitable for charging systems (and solar) for 48vdc battery systems. Thanks for the review!

App Privacy

The developer, Juggernaut Technology, Inc., indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy.

Data Not Collected

The developer does not collect any data from this app.

Privacy practices may vary, for example, based on the features you use or your age. Learn More


  • Family Sharing

    Up to six family members can use this app with Family Sharing enabled.

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