PES Tools
Free Trade Tools
Calculators and NEC reference charts built for working electricians, HVAC techs, and solar installers — free, fast, and no sign-up. Size it right, then get it quoted.
Flagship Calculators
The three most-used tools on the site — each with a full NEC-referenced guide and a ready-to-copy embed.
Duct Size Calculator
CFM in, exact round or rectangular duct size out — equal-friction method.
Conduit Fill Calculator
NEC Chapter 9 fill math for EMT, PVC & RMC in seconds.
Breaker Sizing Calculator
Size breakers and wire to the NEC 125% continuous-load rule.
Sizing Tools
Wire, breakers, generators, batteries, inverters, EV circuits — sized to code.
Voltage Drop Calculator (NEC)
Size wire so long runs stay inside the 3%/5% NEC voltage-drop limits.
Battery Runtime Calculator
Volts, amp-hours, DoD & load to real hours of runtime.
Solar Panel Sizing Calculator
Monthly kWh + peak sun hours to array kW and panel count.
Generator Sizing Calculator (Load List)
Build your load list — running watts, surge, recommended kW.
Wire Ampacity Calculator (NEC 310.16)
Load amps + ambient/bundling conditions to the right AWG or kcmil.
Conversion Tools
Amps, watts, volts, kW, kVA, kWh — convert anything on the truck, no app needed.
kVA to Amps Calculator
Transformer & generator kVA to full-load amps, single or three phase.
Watts to Kilowatts Calculator
W ↔ kW instantly, plus kWh/day from your run hours.
MWh to kWh Calculator
Utility-scale energy units converted, with real-world equivalents.
Trade & Project Tools
Landed cost, ROI, and fuel math for quotes and bids.
Conduit Bending Calculator
Offset multipliers, shrinkage & bend marks for 10°–45° bends.
Service Entrance Load Calculator
NEC 220 standard method — dwelling load to service amps.
EV Charger Circuit Calculator (NEC 625)
Charger amps to breaker & wire size per NEC 625.
Off-Grid Battery Bank Calculator
Daily kWh × autonomy days to bank kWh, amp-hours & modules.
Reference Charts
Print-friendly NEC and sizing charts — the ones taped to the gang box.
Buying for a job?
The tools spec it — we quote it. Send your bill of materials for contractor pricing, or join the PES installer network for standing trade discounts and priority freight.
Tools FAQ
Are these calculators really free?
Yes. Every PES trade tool is free to use with no sign-up and no limits. They are built by Portlandia Electric Supply to help contractors, installers, and DIYers plan jobs correctly the first time.
Are the electrical calculators based on the NEC?
Yes. The breaker, wire, and conduit tools use NEC 310.16 ampacity tables, NEC Chapter 9 conduit-fill tables, NEC 240.6 standard breaker sizes, and the 125% continuous-load rule. Always confirm final designs with your Authority Having Jurisdiction (AHJ).
Can I embed a calculator on my own website?
Yes. Each flagship tool page is embed-ready: open the full guide for the tool and use the 'Embed this calculator' toggle to copy a ready-made iframe snippet with a follow link.
Do the tools work for commercial projects?
Yes. The sizing tools cover residential through light-commercial scenarios. For project or volume pricing on the equipment the tools spec, request a project quote or join the PES installer network for trade pricing.
How accurate are the results?
The tools use engineering-standard formulas and current NEC tables and are intended for planning and estimating. Final system designs should be verified by a licensed electrician or engineer.