Calculators
274 engineering calculators across 12 disciplines. Pick a discipline on the left. Included with the All-Access pass.
Electrical & Power Systems
52 calculatorsPanel Schedule Builder
Build and balance panel schedules with automatic phase assignment.
Commercial Load Calculation
NEC 220 Part III demand load analysis by occupancy type.
Demand Load Summary
Aggregate multiple panels and feeders into a main service calculation.
Ampacity
NEC 310.15 conductor ampacity calculator with temperature correction and bundling derating factors. Covers THWN, XHHW, USE-2, and more conductor types.
Arc Flash
IEEE 1584 arc flash analysis. Calculate incident energy (cal/cm²), PPE category, arc flash boundary, and required working distance for electrical safety.
Battery Peukert Discharge
Peukert's Law calculator: find actual battery discharge time under a real load current, and see how much shorter it runs than the naive C/I estimate.
Battery Recharge Time
Battery recharge calculator: find the ampere-hours discharged and the charge current needed to recharge a battery bank within a target time, including a 10%…
Battery Soc Cycle Aging
Battery state-of-charge and cycle aging calculator — model depth-of-discharge limits, cycle life at operating DoD, and calendar aging for LFP and NMC chemistries.
Bess Capacity Sizing Calculator
Battery energy storage (BESS) capacity sizing calculator — find the nameplate kWh, inverter kW rating, and number of battery units needed for backup power or solar…
Bess Roi Payback Calculator
BESS ROI calculator — compute annual throughput, degradation-adjusted payback period, and lifetime net savings for a battery storage project.
Bess Round Trip Efficiency
Battery storage (BESS) round-trip efficiency calculator — find usable kWh from rated capacity given charge/discharge losses, plus cycle life and annual throughput.
Bonding Conductor Sizing
Bonding conductor sizing calculator per NEC Table 250.66: find the grounding electrode conductor / main bonding jumper size from the service conductor size, copper or…
Conduit Fill
Conduit fill calculator verifying compliance per NEC Chapter 9, Table 1. Supports EMT, RMC, IMC, PVC, and LFNC with multiple conductor types and sizes.
EV Charging Demand Load
EV charging demand load calculator — size total electrical demand from charger count, kW rating, and the diversity factor per NEC 625.42 for service planning.
Generator Sizing
Standby and emergency generator sizing calculator per NFPA 110. Size by connected loads, demand factors, and motor starting kVA to a standard generator kW rating.
Grounding
Grounding calculator to size equipment grounding conductors (EGC) and grounding electrode conductors (GEC) per NEC 250.122 and 250.66 based on OCPD rating.
Harmonic Distortion Simulator
IEEE 519 harmonic distortion simulator. Calculate THD/TDD from VFD and nonlinear-load harmonic spectra and check compliance against Isc/IL-based current distortion…
Hv Corona Onset
Corona onset (critical disruptive voltage) calculator using Peek's formula for overhead transmission conductors. Enter radius, spacing, and air density factor.
Hv Ground Grid Ieee80
Substation ground grid calculator: simplified IEEE 80 grid resistance (Sverak's formula) plus tolerable touch/step voltage limits from soil resistivity, grid area, and…
Hv Sag Tension
Overhead conductor sag calculator using the parabolic approximation D = wS²/(8T). Enter unit weight, span, and tension (or %RBS) and check ground clearance.
Inverter Sizing Clipping Ratio
Size inverter AC capacity against a PV array's DC nameplate rating and calculate the clipping ratio.
Itc Macrs Tax Incentive
Solar ITC and MACRS calculator — estimate the 30% federal Investment Tax Credit, 5-year MACRS depreciation, and state incentives for renewable project economics.
Lightning Protection Design
Lightning protection shielding calculator using the NFPA 780 / IEEE 998 rolling sphere method — check whether a mast or shield wire protects equipment from a direct…
Load Calc
Electrical load calculator (NEC Article 220): calculate residential and commercial electrical load, apply demand factors, and size the service entrance and panel from…
Motor Calc
NEC 430 motor branch circuit sizing calculator — conductor ampacity, overcurrent protection, overload relay, and disconnecting means for any motor load.
Nameplate Design Generator
Turn motor, transformer, pump/VFD, generator, or panel nameplate data into a linked design package: SVG one-line diagram, equipment schedule, bill of materials, and wire…
NEC 314 16 Box Fill
NEC Table 314.16(B) box fill calculator: enter conductor counts by gauge plus clamp, device, and grounding conductor allowances, then check against your box size.
NEC 690 7 Max System Voltage
NEC 690.7 maximum PV system voltage calculator — temperature-correct string open-circuit voltage (Voc) at the lowest expected ambient to verify equipment ratings.
NEC 690 PV Array Current Ocpd
NEC 690.8(A)(1) PV array current calculator — apply the 1.25 × 1.25 factors to size conductor ampacity and overcurrent protection (OCPD) ratings fast.
NEC 705 Interconnection Limit
NEC 705 interconnection calculator — apply the 120% busbar rule to find the allowable inverter output current from the panel main breaker and busbar rating.
Ohms Law Calculator
Online Ohm's law calculator. Enter any two known values — voltage (V), current (A), resistance (Ω), or power (W) — and instantly calculate all four quantities with the…
Panel Schedule
3-phase panel load balancer. Distribute circuit loads across Phase A, B, and C, then calculate phase totals, percent imbalance, and total panel demand.
Peak Demand Load Factor
Turn a facility's annual kWh consumption and peak kW demand into load factor and the related demand figures.
Power Factor
Power factor correction calculator. Determine the capacitor bank size (kVAR) needed to reach a target PF, cut apparent power, and lower utility demand charges.
Renewable Interconnection Screening
Fast-track interconnection screening calculator for solar, wind, and BESS projects — modeled on FERC SGIP fast-track screens and IEEE 1547-2018…
Short Circuit
Short circuit calculator for available fault current at the transformer secondary using the impedance method. Find minimum interrupting ratings for breakers and fuses.
Short Circuit Study
Short-circuit study calculator using the Point-to-Point Method: transformer secondary fault current plus downstream conductor impedance, for radial single-source systems.
Solar Payback Irr
Solar payback and IRR calculator — compute simple payback, NPV, and internal rate of return from installed cost, annual savings, incentives, and panel degradation.
Solar PV Array Sizing Calculator
Solar PV array sizing calculator — estimate system size (kW DC), panel count, annual production, and roof area needed to offset your electric bill from annual usage and…
Substation Battery Sizing
Substation station-service DC battery sizing calculator using a simplified IEEE 485 duty-cycle method — required ampere-hour capacity and recommended series cell count…
Three Phase Power Calculator
Three-phase power calculator: solve for real power (kW), apparent power (kVA), reactive power (kVAR), and current from voltage, amps, and power factor using the √3…
UPS Sizing Calculator
UPS sizing calculator: required UPS kVA rating from critical load kW, output power factor, and a derating margin, plus a rough VRLA vs Li-ion battery runtime energy…
Voltage Divider Calculator
Voltage divider calculator. Enter Vin, R1, and R2 to instantly calculate Vout, current through the divider, power dissipated in each resistor, and the R2/(R1+R2) ratio.
Voltage Drop
Conductor voltage drop calculator per NEC 210.19. Verify branch circuits and feeders stay within the recommended 3% (5% total) drop and size conductors right.
Wind Turbine Aep
Wind turbine AEP calculator — estimate annual energy production in kWh by integrating a Weibull wind speed distribution (k, c) against the turbine power curve.
Wire Ampacity Calculator
NEC wire ampacity calculator using Table 310.16. Select conductor material, wire gauge, and temperature rating, then apply ambient temperature correction (310.15(B)(1))…
Wire Size For Amp Breaker
Quick-reference wire sizing chart for common breaker amperages (15A–200A) per NEC Table 310.16, plus the difference between rule-of-thumb sizing and a full ampacity…