Electrical & HVAC Job-Site Calculator Hub (5-in-1)

Fast, code-referenced calculators for electricians, HVAC techs, and engineers—all on one page or via 60+ instant NEC reference charts below.

1. NEC Conduit Fill Calculator (Chapter 9, Tables 1, 4 & 5)

Conduit Material

Conduit Trade Size

Conduit Nipple ≤ 24" (60% Fill)

Primary Wire Insulation

Primary Wire Gauge

Primary Wire Count

Secondary / Ground Insulation

Secondary / Ground Gauge

Secondary Wire Count

Recommended Job-Site Materials & Tools for This Run

Trade Size	Internal Dia.	Total Area	Bundle Fill %	Max Primary Wires	NEC Status

2. NEC Wire Size & Ampacity Calculator (Table 310.16)

Load Current (Amps)

Conductor Metal

Terminal Temp Rating

Conductors in Raceway

Continuous Load (runs 3+ hours continuously — apply NEC 125% rule)

Recommended Wire, Breakers & Termination Tools

3. Voltage Drop Calculator (NEC 3% Branch / 5% Feeder Rule)

System Phase

Conductor Metal

System Voltage (V)

Wire Gauge

One-Way Run Length (Feet)

Load Current (Amps)

Bulk Wire & Voltage Testing Gear

4. Transformer Sizing (kVA) & Full-Load Amps Calculator

Transformer Phase

Primary Voltage (V)

Secondary Voltage (V)

Secondary Load (Amps)

Include 25% Future Expansion & Continuous Margin (1.25x)

Dry-Type Transformers & Safety Disconnects

5. HVAC Air Changes Per Hour (ACH) & Exhaust Fan CFM Calculator

Room Length (ft)

Room Width (ft)

Ceiling Height (ft)

Target Air Changes / Hr (ACH)

Commercial Exhaust Fans & Airflow Meters

NEC Quick-Lookup Charts (60+ Field Reference Pages)

Select any wire size, conduit trade size, or circuit breaker amperage below for instant NEC Chapter 9 and Table 310.16 calculations: