Free printable electrician math formula sheet. Voltage drop, load calculations, motor circuit sizing, transformer formulas, conduit fill, and box fill — all formulas on one page.

What’s inside

• Ohm's Law and power formulas (V=IR, P=VI, P=I²R)
• Voltage drop formula — single-phase and three-phase with K values
• Common conductor CM areas (14 AWG through 250 kcmil)
• Dwelling load calculations with demand factors (Table 220.42)
• Motor circuit sizing — conductors, OCPD, overloads (Art. 430)
• Transformer kVA and current formulas — 1-phase and 3-phase
• Conduit fill percentages (Ch. 9, Table 1) and box fill rules (Art. 314.16)

How to download / print

1. Click Open Printable Version below.
2. In the new tab, click the blue Save as PDF / Print button at the top.
3. Your browser print dialog opens — choose Save as PDF (Ctrl+P / Cmd+P).
4. To print on paper: choose your printer and select Fit to page.

This guide is for study use only. It is a quick reference, not a substitute for the full NEC codebook or official exam preparation materials.