NEC Calculator Suite
The NEC 2026 calculator suite built for electricians
Free, code-accurate calculators with dual citation — every result shows both the 2026 and 2023 article numbers, so your answer holds whichever edition your AHJ has adopted.
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Voltage Drop Calculator
Calculate AC/DC voltage drop and select conductor size per NEC §210.19 and §215.2 recommendations (3% branch, 5% overall). Uses Chapter 9 Table 9 resistance.
Open Most usedWire Gauge Calculator
Find the minimum conductor size (AWG/kcmil) for any electrical load per NEC §310.16. Supports 60°C, 75°C, and 90°C ratings, continuous loads (125%), and parallel runs.
Open Most usedConduit Fill Calculator
Calculate raceway fill percentage and minimum conduit size per NEC Chapter 9 Tables 1, 4, and 5. Supports EMT, IMC, RMC, PVC-40, PVC-80, ENT, FMC, and LFMC with mixed wire sizes.
Open Most usedResidential Load Calculator
Calculate single-family and multifamily residential electrical service load using NEC 2026 Article 120 (formerly Article 220) standard & optional methods with 2026/2023 dual citations.
OpenLoad Calculations & Branch Circuits
View categoryResidential Load Calculator
Calculate single-family and multifamily residential electrical service load using NEC 2026 Article 120 (formerly Article 220) standard & optional methods with 2026/2023 dual citations.
Open NEC 2026 / 2023Existing Dwelling Added Load Calculator
Calculate if new electrical loads (EV charger, heat pump, hot tub) can be added to an existing residential panel without a 200A service upgrade per NEC 2026 §120.83 (formerly §220.83).
Open NEC 2026 / 2023Service & Panel Upgrade Advisor
"Do I need a 200A panel?" — Evaluate if adding an EV charger, heat pump, or induction range requires upgrading your 100A or 150A panel under NEC Article 230 and §120.83.
Open NEC 2026 / 2023Maximum Demand from Utility Data
Calculate electrical service sizing from 12-month utility interval meter data using the NEC 2026 §120.87 (formerly §220.87) 125% peak demand method.
Open NEC 2026 / 2023EV Charger Load Calculator
Calculate Level 2 EVSE dedicated circuit breaker, 125% continuous conductor size, and service calculation demand per NEC 2026 §120.57 and Article 625.
Open NEC 2026 / 2023Commercial Kitchen Demand Load (NEC Table 120.56)
Calculate commercial kitchen cooking equipment demand factors (65%–100%) and the two-largest-unit floor rule per NEC Table 120.56 (220.56).
Open NEC 2026 / 2023NEC General Demand Factor Calculator
Calculate demand factors for general lighting (§120.42), electric clothes dryers (Table 120.54), and cooking ranges (Table 120.55) per NEC 2026 Art. 120.
Open NEC 2026 / 2023Panel Schedule & Load Balancing Calculator
Calculate panelboard phase loads (Phase A/B/C), percentage phase imbalance, neutral current, and bus utilization per NEC §408.4.
Open NEC 2026 / 2023Neutral & Grounded Conductor Sizing
Size feeder and service neutral conductors with 70% unbalance reduction (>200A), range/dryer derates, and harmonic rules per NEC 2026 §120.61.
Open NEC 2026 / 2023Kitchen & Laundry Circuit Planner
Size mandatory 20A small appliance circuits, laundry circuits, garage circuits, and dedicated appliance breakers per NEC §210.11(C).
Open NEC 2026 / 2023Receptacle Spacing Planner (6/12 Rule)
Calculate minimum receptacle outlets, maximum spacing, and layout compliance for rooms, kitchen countertops, and hallways per NEC §210.52.
OpenConductors, Conduit & Raceways
View categoryWire Gauge Calculator
Find the minimum conductor size (AWG/kcmil) for any electrical load per NEC §310.16. Supports 60°C, 75°C, and 90°C ratings, continuous loads (125%), and parallel runs.
Open NEC 2026 / 2023Voltage Drop Calculator
Calculate AC/DC voltage drop and select conductor size per NEC §210.19 and §215.2 recommendations (3% branch, 5% overall). Uses Chapter 9 Table 9 resistance.
Open NEC 2026 / 2023Wire Ampacity Chart & Reference Lookup
Interactive NEC Table 310.16 & Table 310.17 wire ampacity chart with ambient temperature and conduit bundling adjustment calculators.
Open NEC 2026 / 2023Conductor Derating Calculator
Calculate adjusted conductor ampacity when bundling more than 3 current-carrying conductors (§310.15(C)(1)) and correcting for elevated ambient temperatures (§310.15(B)(1)).
Open NEC 2026 / 2023Conduit Fill Calculator
Calculate raceway fill percentage and minimum conduit size per NEC Chapter 9 Tables 1, 4, and 5. Supports EMT, IMC, RMC, PVC-40, PVC-80, ENT, FMC, and LFMC with mixed wire sizes.
Open NEC 2026 / 2023Box Fill Calculator
Calculate electrical junction box and device box fill volume in cubic inches per NEC §314.16. Covers conductors, devices, internal clamps, studs, and grounding wires.
Open NEC 2026 / 2023Pull & Junction Box Sizing Calculator
Determine minimum pull and junction box dimensions for conductors #4 AWG and larger per NEC §314.28. Covers 8× straight pulls, 6× angle pulls, and U-pulls.
Open NEC 2026 / 2023Conduit Body & Mogul LB Calculator
Size standard and Mogul conduit bodies (LB, LL, LR, T, C), cubic inch volume for < #4 AWG, and 6×/8× rules for ≥ #4 AWG per NEC §314.28.
Open NEC 2026 / 2023Conduit Bending Calculator
Calculate offset multipliers, shrink, 90° stub-up take-up, 3-point and 4-point saddles, rolling offsets, and 360° bend limits for EMT & RMC.
Open NEC 2026 / 2023Cable Tray Fill Calculator
Calculate minimum cable tray width and allowable fill area for ladder, ventilated, and solid bottom trays per NEC Article 392 and §392.22.
Open NEC 2026 / 2023Wire Pulling Tension Calculator
Calculate conduit wire pulling tension, bend multiplier, Sidewall Bearing Pressure (SWBP), and pulling grip limits per IEEE 576 & NEC Ch. 9.
Open NEC 2026 / 2023Conduit & Cable Support Spacing Lookup
Lookup maximum support strapping intervals and distance from boxes for NM, MC, EMT, RMC, PVC, and FMC per NEC Chapters 3.
Open NEC 2026 / 2023MC Cable Connector Spacing & Gutter Sizing
Calculate knockout center-to-center spacing for MC cable connectors, locknut clearances, and panel wire-bending gutters per NEC §330.30 & §312.6.
Open NEC 2026 / 2023Tap Conductor Rules Calculator
Calculate 10-foot (1/10th ampacity) and 25-foot (1/3rd ampacity) feeder tap conductor sizing and termination protection per NEC §240.21(B).
Open NEC 2026 / 2023Underground Duct Bank Ampacity
Calculate underground electrical duct bank ampacity, mutual heating derate factors, soil RHO, and conduit configurations per NEC Annex B.
Open NEC 2026 / 2023Underground Burial Depth Calculator
Find minimum underground burial depth (cover) per NEC §300.5 Table 300.5. Covers Direct Burial (UF-B), Rigid Metal Conduit (RMC), PVC Schedule 40/80, residential GFCI circuits, and driveways.
OpenGrounding, Bonding & Safety
View categoryEquipment Grounding Conductor Sizing
Size the equipment grounding conductor (EGC) per NEC §250.122 based on circuit breaker/fuse rating. Includes parallel conductor rules (§250.122(F)) and voltage drop upsizing (§250.122(B)).
Open NEC 2026 / 2023Grounding Electrode Conductor Sizing
Size the Grounding Electrode Conductor (GEC) from the largest service entrance conductor per NEC §250.66. Applies ground rod, concrete-encased (Ufer), and ground ring electrode caps.
Open NEC 2026 / 2023Grounding Electrode System Builder
Design compliant grounding electrode systems: concrete-encased Ufer, 25-ohm dual rods, water pipe supplemental rules, and GEC limits per NEC §250.50–68.
Open NEC 2026 / 2023Bonding Jumper Sizing Calculator
Size Main Bonding Jumpers (MBJ), System Bonding Jumpers (SBJ), and Supply-Side Jumpers (SSBJ) per NEC §250.102 & Table 250.102(C)(1).
Open NEC 2026 / 2023GFCI vs AFCI Requirement Checker
Determine where GFCI protection (§210.8) and AFCI protection (§210.12) are required by room, location, voltage, and occupancy type (dwelling vs commercial) under NEC 2026/2023.
Open NEC 2026 / 2023Pool & Spa Bonding Calculator
Calculate equipotential bonding grid requirements, pool pump GFCI protection, and overhead wire clearances per NEC Article 680.
Open NEC 2026 / 2023Electrical Panel Clearance Calculator
Calculate NEC §110.26 clear working depth (Conditions 1/2/3), 30" width, 6.5ft headroom, and dedicated equipment space for electrical panels.
Open NEC 2026 / 2023Terminal Torque & Tightening Lookup
Look up electrical termination torque values (lb-in, lb-ft, N·m) for lugs, breakers, and screws per NEC §110.14(D) & Table 110.14(D).
Open NEC 2026 / 2023NEMA Plug & Receptacle Configuration Lookup
Lookup pinouts, voltages (120V–480V), wire sizes, breaker ratings & wire color codes for NEMA 5-15, 14-50, L14-30 & all NEMA WD-6 devices.
OpenMotors, Transformers & Protection
View categoryMotor Branch Circuit Calculator
Size conductors, OCPD, thermal overload protection, and disconnect switch for AC electric motors per NEC Article 430 and Tables 430.248 & 430.250.
Open NEC 2026 / 2023Transformer Sizing & OCPD Calculator
Size low-voltage dry-type and liquid transformers (kVA), calculate primary/secondary Full-Load Amps (FLA), size 125% OCPD per NEC §450.3(B), and estimate secondary fault current.
Open NEC 2026 / 2023Overcurrent Protection Selector
Select the standard circuit breaker or fuse size per NEC §240.6(A). Applies the 125% continuous load factor, conductor ampacity protection, and §240.4(B) next-size-up rule.
Open NEC 2026 / 2023Fault Current / AIC Calculator
Calculate available short-circuit fault current (AFC) and Ampere Interrupting Capacity (AIC) at service panels using the point-to-point method per NEC §110.24 and §110.9.
Open NEC 2026 / 2023Arc Flash Incident Energy Calculator
Estimate arc flash incident energy (cal/cm²), flash boundary distance, NFPA 70E PPE Category, and NEC §110.16 safety label requirements.
Open NEC 2026 / 2023Electrical Fundamentals & Power Triangle Calculator
Calculate Ohm’s Law (V, I, R, P), 3-phase AC power triangle (kW, kVA, kVAR, PF), horsepower to kW/Amps, and kVA↔Amps conversions.
OpenSolar, Storage & Electrification
View categorySolar 120% Busbar Rule Calculator
Calculate max solar backfeed breaker, allowable inverter AC output, and main breaker derate requirements per NEC §705.12(B).
Open NEC 2026 / 2023Solar PV String & MPPT Sizing Calculator
Calculate temperature-corrected max Voc, min/max modules per string, inverter MPPT window, and 156% DC wire sizing per NEC §690.7 & §690.8.
Open NEC 2026 / 2023Solar Rapid Shutdown & MLPE Sizing (NEC 690.12)
Verify rooftop solar rapid shutdown compliance, inside boundary ≤ 80V / outside ≤ 30V rules, and MLPE devices per NEC §690.12.
Open NEC 2026 / 2023Battery Storage / ESS Sizing Calculator
Size residential and commercial battery storage systems (ESS), backup duration runtime, inverter kW, and 125% circuit OCPD per NEC Article 706.
Open NEC 2026 / 2023HVAC & Heat Pump Circuit Calculator
Calculate Minimum Circuit Ampacity (MCA), Maximum Overcurrent Protective Device (MOCP), and wire sizing for AC & heat pumps per NEC Article 440.
Open NEC 2026 / 2023Generator Sizing Calculator
Size standby and emergency generators, motor starting surge kVA, fuel/altitude derates, and transfer switches per NEC Articles 445 & 702.
Open NEC 2026 / 2023Whole-Home Electrification Simulator
Simulate panel capacity for Heat Pumps, EV Chargers, Induction Ranges, and HPWH on 100A/200A panels per NEC 2026 §120.83 & §120.87.
Open NEC 2026 / 2023Smart Panel & EMS Load Calculator
Size automated Energy Management Systems (EMS) and smart panels to add EVSE & heat pumps without panel upgrades per NEC 2026 Art. 130 & §625.42.
Open NEC 2026 / 2023Energy Cost Calculator — Electricity & kWh
Calculate equipment electricity running costs ($/day, $/month, $/year) based on wattage, operating hours, and local utility $/kWh rates.
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