Beckify Electrical Engineering Toolbox
Transformer Sizing Calculator
Select a standard kVA and apply NEC Table 450.3(B): primary-only or primary+secondary protection, Note 1 next-size-up on or off, optional continuous 125%.
About this calculator
Use this free browser-based calculator to work through the relevant electrical inputs, review the result, and compare it with field conditions.
For design, installation, or safety decisions, verify assumptions against the applicable code edition, equipment documentation, and site requirements.
Open the interactive tool