Overview Downloads Buy Now Free to Try Freeware Upgrades Contact Us

Voltage Drop Calculator

This application, revised to meet 2020 NEC and 2021 CEC, provides voltage drop calculations in accordance with the US National Electrical Code Tables 9 and 8 for AC and DC feeders. Colour coding of maximum allowable ampacity (at different ambient temperatures) in accordance with US and Canadian codes - helps choose the correct wire size. Full Load Amperes for typical motors are built-in. The calculator estimates feeder operating temperature and allows for setting the feeder resistance values closer to the operating temperature and see the effect on the voltage drop. For wires or cables different than listed in Table 9 space is provided to facilitate calculation using manufacturer provided parameters.

Voltage drop equals energy loss. With rising cost of electricity you may find the "Feeder Efficiency Tip" useful. It informs when it may be beneficial to increase wire size above the minimum required by codes. Download.

Voltage Drop Calculator - Calculation Software


Helps select proper wire size by colour coding while taking insulation rating and ambient temperature into account. Produces calculation report for record. Estimates full load current of motors based on Horse Power rating.


Enter and modify values in any sequence, use metric or imperial units, AC and DC. Calculates on the fly. Paste results to any text application or spreadsheet. Displays DC voltage drop for comparison with AC. Has built-in wire ampacity tables for US and Canada.

Easy to Use

All terms and definitions are explained on screen. No manual required.

What's New

Specifies conductor parameters used in calculation, which is useful for verification. Has spaces for calculation with cable manufacturer parameters.


Customer Reviews

"Electrical Calculator is a simple, useful and effective application worth having when you need to quickly calculate and estimate available short circuits. Specially intended for electrical engineers and contractors, Electrical Calculator enables you to perform various calculations and determine the values on both sides of the transformer. The application comes with a user-friendly interface and enables you to change the primary voltage and current as you prefer, then quickly view all the generated results." – Softpedia Review

"Underground Cable Ampacity is a handy application designed to enable you to find the allowable ampacity for underground cable configurations by looking at the tables and diagrams of the Canadian Electrical Code. Using this underground cable ampacity calculator you will be done in a minute. It will save you hours in a year, and most importantly it will reduce the chance of making an error." – Softpedia Review

"Electrical Calculator proves to be a useful and reliable application whose main purpose is to provide electrical engineers with the right tools when calculating the transformer primary and secondary current, protection and selecting downstream equipment interrupting capacity rating. "– Softpedia Review

"NEC Ampacity Calculator is an efficient piece of software ... dedicated to users that need to often look-up NEC tables and apply correction factors." – Softpedia Review