Cerrowire’s Voltage Drop, Conduit Fill and Amperage Calculator is a must have for all electrical professionals. The most commonly needed tools are presented in one easy-to-use calculator.

This app consists of three separate calculators that calculate the minimum wire size needed for a run of an inputted length to stay within a recommended voltage drop percentage, the fill % based on the cables and conduit used, and the amperage of a cable (per the NEC Table 310-15(B)(16)) based on wire size, wire type and temperature.


• Single app for multiple tools
• Easy-to-use interface with tabs for each calculator
• Calculates voltage drop for 120 Volts, 208 Volts, 120/208 Volts (4 Wire), 240 Volts, 277 Volts, 480 Volts, or 277/480 Volts (4 wire) voltages.
• Works for either copper or aluminum conductors.
• Works for THHN/THWN, XHHW, or USE conductor types.
• Conduit fill calculator works for EMT, ENT, FMC, IMC, PVC, Type EB PVC, LFNC-A, LFNC-B, LFMC, and RMC conduit types.
• Conduit fill calculator works for 14 AWG through 750 MCM conductor sizes.
• Amperage calculator works for 14 AWG through 1000 MCM conductor sizes.

What’s New

Version 1.0.5

- Label change for iPad

Ratings and Reviews

3.6 out of 5
11 Ratings
11 Ratings
Mr.Picky ,

Best All Around Free App in Category

Both Southwire & Paige Apps require you to ‘agree’ to Indemnify & Hold Harmless their companies and employees from litigation. For a free app?! No way should you EVER give up your rights or allow companies to think this overreaching boilerplate is acceptable or the ‘norm’. When you ‘Indemnify’ you are agreeing to pay for any claims… Oh, now you get it.
Look the NEC is complex, some app's quick reference is only a starting point, there are multiple factors yet to be reviewed and existing conditions evaluated before a definitive or appropriate answer can be reached. The Cerrowire App also includes three handy apps in one an attractive layout (conduit fill + gauge to amperage) and the Conduit Fill app allows for multiple gauges in same conduit making it very useful for real world applications. I download these and a bunch more and the only one I am keeping is the CerroWire Apps.

Cosmo708 ,

Really Happy that I found this app!!

This app has made it easy to come up with the awg need to run my power. I do have one suggestion, I have come across where the customer has to calculate the power with a .5 and 1% voltage drop. This would be a great addition to the app.

Thanks, and doing what you do.

Mr. Sleep Incorporated ,

Need to fix

If you are using the voltage drop portion to calculate the size of wire needed for a given distance then there is an error in the app. If the size of wire needed for the run exceeds 1000 kcmill than the app displays an erroneous awg needed. It should just display "Error" or "maximum awg exceeded. " For example-at 2% max voltage drop a 100 amp circ. at 930 feet displays 1000kcmill needed, a 100 amp circ. at 931 feet displays #3awg needed! This could really cause issues for someone that blindly follows this app!


Cerro Wire LLC
789.6 KB
Requires iOS 5.1 or later. Compatible with iPhone, iPad, and iPod touch.
Age Rating
Rated 4+
© Cerrowire, LLC


  • Family Sharing

    With Family Sharing set up, up to six family members can use this app.

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