All 100 Precision Electrical Engineering Calculators

Explore all 100 precision calculators and sizing utilities below. Every calculator provides real-time computation, step-by-step mathematical substitution derivations, NEC 2023/2026 safety compliance limits, and standard benchmark comparison tables.

Ohm & Watt Core

Ohm's Law Master 4-in-1 Solver

Universal circuit analysis, physics students, EE engineers, electronics repair.

V = I × R Open →

Ohm & Watt Core

Watts to Volts Calculator

Power supply design, audio speaker amplifier matching, test bench setup.

V = P / I (Current) Open →

Ohm & Watt Core

Volts to Watts Calculator

Determining heater element power, voltage step-up/step-down power delivery.

DC: W = V × I Open →

Ohm & Watt Core

Volts to Amps Calculator

Determining current draw when plugging a device into variable voltage supplies.

I = V / R (Ohm's) Open →

Ohm & Watt Core

Ohms to Watts Calculator

Selecting correct resistor wattage rating (1/4W, 1/2W, 1W, 5W, 10W) without burnout.

P = I² × R (with Amps) Open →

Ohm & Watt Core

Watts to Ohms Calculator

Heating element coil fabrication, vape wire coil resistance, dummy load sizing.

R = V² / P Open →

Ohm & Watt Core

Ohms to Amps Calculator

Circuit board debugging, measuring short-circuit current, sensor current loops.

I = V / R Open →

Ohm & Watt Core

Amps to Ohms Calculator

Verifying motor winding health, identifying degraded electrical connections.

R = V / I Open →

Ohm & Watt Core

Joules to Watts Calculator

Laser pulse power, capacitor discharge energy, physics and thermodynamics calculations.

W = J / t(seconds) Open →

Ohm & Watt Core

Watts to Joules Calculator

Calculating total heat generation, surge protector energy absorption ratings.

J = W × t(seconds) Open →

Ohm & Watt Core

BTU/hr to Watts Converter

HVAC thermal capacity to electrical sizing, heat pump performance calculation.

W = BTU/hr × 0.293071 Open →

Ohm & Watt Core

Watts to BTU/hr Converter

Data center server room cooling load planning, electrical enclosure thermal design.

BTU/hr = W × 3.412142 Open →

Battery & Solar

Battery Run Time Calculator

Off-grid cabin power planning, RV camping, UPS backup runtime.

Hours = (Ah × V × DoD × InverterEff) / LoadWatts Open →

Battery & Solar

Battery Charge Time Calculator

Sizing car battery chargers, marine battery maintenance, solar charging duration.

Hours = [Battery Ah × (1 - CurrentSoC)] / (Charger Amps × ChargeEfficiency) Open →

Battery & Solar

mAh to Wh Converter

Power bank airline travel compliance, drone battery rating, smartphone battery comparisons.

Wh = (mAh × V) / 1000 Open →

Battery & Solar

Wh to mAh Converter

Converting laptop power bank ratings to phone recharge cycle equivalents.

mAh = (Wh × 1000) / V Open →

Battery & Solar

mAh to Ah Converter

Standardizing battery specs across small electronics and larger solar batteries.

Ah = mAh / 1000 Open →

Battery & Solar

Ah to mAh Converter

Translating deep-cycle battery specs for electronic hobbyists.

mAh = Ah × 1000 Open →

Battery & Solar

Watt-Hours to Amp-Hours Converter

Sizing battery banks for solar generators that advertise capacity in Wh.

Ah = Wh / V Open →

Battery & Solar

Inverter Sizing Calculator

RV electrical build, off-grid van conversion, emergency home backup inverter selection.

Continuous Watts = Σ Running Watts × 1.25 Open →

Battery & Solar

MPPT Solar Charge Controller Sizing Calculator

Off-grid solar design, preventing charge controller overload.

Output Amps = (Total PV Array Watts / Battery Bank Voltage) × 1.25 Open →

Battery & Solar

Solar Panel Daily Output Calculator (Wh / kWh per day)

Calculating how many solar panels are needed to run specific appliances daily.

Daily Wh = Panel Watts × Peak Sun Hours × 0.78 (System Derate Factor) Open →

Battery & Solar

Off-Grid Battery Bank Sizing Calculator

Solar cabin sizing, marine long-range cruising electrical design.

Bank Ah = (Daily Wh × Days of Autonomy) / (System Volts × DoD × InverterEff) Open →

Battery & Solar

Solar Panel Angle & Tilt Optimization Calculator

Rooftop and ground-mount solar installation alignment.

Summer = Lat - 15° Open →

Battery & Solar

Battery C-Rate to Amps Calculator

RC drones, LiPo battery charging limits, EV battery pack discharge capability.

Current (A) = C-Rate × Capacity (Ah) Open →

Battery & Solar

Battery Internal Resistance & Voltage Sag Calculator

EV acceleration battery analysis, power tool high-draw performance.

V_sag = I × R_internal Open →

Battery & Solar

Lithium vs Lead-Acid Battery Usable Capacity Comparison Calculator

RV/Marine/Solar buyers deciding whether to upgrade to lithium batteries.

Usable Wh = Rated Wh × DoD × Peukert Efficiency Open →

Battery & Solar

Solar PV String Wire Sizing & Voltage Drop Calculator

Connecting roof/ground solar arrays to charge controllers over long distances.

ΔV = (2 × L × I_sc × 1.25 × ρ) / A_cmil Open →

Industrial & Motor

Horsepower to Amps Calculator (HP to Amps)

Electric motor installation, pump sizing, industrial maintenance.

1-Phase: I = (HP × 746) / (V × η × PF) Open →

Industrial & Motor

Amps to Horsepower Calculator (Amps to HP)

Determining unknown motor rating from nameplate voltage and clamp meter amperage.

1-Phase: HP = (I × V × η × PF) / 746 Open →

Industrial & Motor

HP to kW Calculator

Converting US equipment specs for European metric industrial machinery.

kW = HP × 0.74569987 (Mechanical) Open →

Industrial & Motor

kW to HP Calculator

Importing machinery, electric vehicle motor power comparisons.

HP = kW / 0.74569987 = kW × 1.34102 Open →

Industrial & Motor

kVA to kW Calculator

Generator load sizing, UPS capacity calculation.

kW = kVA × PF Open →

Industrial & Motor

kW to kVA Calculator

Sizing commercial backup generators and utility transformers.

kVA = kW / PF Open →

Industrial & Motor

kVA to Amps Calculator (Single & 3-Phase)

Substation transformer secondary breaker sizing, generator feeder cable selection.

1-Phase: I = (kVA × 1000) / V Open →

Industrial & Motor

Amps to kVA Calculator

Utility load factor auditing, checking transformer loading percentage.

1-Phase: kVA = (I × V) / 1000 Open →

Industrial & Motor

Three-Phase Power Triangle Calculator (kW, kVA, kVAR)

Commercial plant power quality analysis, avoiding utility reactive power penalties.

P = √3 × V × I × cosθ Open →

Industrial & Motor

Power Factor Correction Capacitor Sizing Calculator

Industrial energy management, eliminating utility low-PF surcharge fees.

kVAR_required = kW × [tan(arccos(PF_initial)) - tan(arccos(PF_target))] Open →

Industrial & Motor

Motor Locked Rotor Amps (LRA) to Running Amps (FLA) Calculator

HVAC technician generator sizing, determining if a generator can start an AC compressor.

FLA = LRA / NEMA_Ratio (Typically LRA ≈ 5.5 to 7.0 × FLA per NEMA Code Letter) Open →

Industrial & Motor

Motor Synchronous Speed & Slip Calculator

VFD drive setup, motor troubleshooting, checking mechanical motor overload.

Ns = (120 × f) / Poles Open →

Industrial & Motor

Motor Efficiency Calculator

Energy auditing, comparing standard vs premium efficiency motors for ROI.

η (%) = [(HP × 746) / Input Electrical Watts] × 100 Open →

Industrial & Motor

Transformer Sizing & Full Load Current Calculator

Commercial electrical engineering, dry-type step-down transformer installation.

Primary I = (kVA × 1000) / (V_pri × √3) Open →

Electrician Trade & NEC

Conduit Fill Calculator (NEC Chapter 9 Tables)

Electricians pulling wires in conduit without code violations or physical jamming.

Fill % = [Σ Conductor Areas / Conduit Internal Area] × 100 ≤ 40% (for ≥3 wires) or 31% (for 2 wires) or 53% (for 1 wire) Open →

Electrician Trade & NEC

Electrical Box Fill Calculator (NEC 314.16)

Electrical rough-in inspections, preventing overcrowded junction boxes and fire hazards.

Volume Required = Σ (Conductor Volume Allowance per Table 314.16(B)) Open →

Electrician Trade & NEC

Circuit Breaker Sizing Calculator (NEC 80% / 125% Rule)

Panel schedule planning, safe breaker selection for EV chargers, heaters, and lighting.

Minimum Breaker Rating = (Continuous Load Amps × 1.25) + Non-Continuous Load Amps Open →

Electrician Trade & NEC

Conductor Ampacity Derating Calculator (Temp & Bundling)

Commercial solar rooftop conduit runs, industrial wiring in hot boiler rooms.

Derated Ampacity = Base Ampacity × Temp Factor (Table 310.15(B)(1)) × Bundling Factor (Table 310.15(C)(1)) Open →

Electrician Trade & NEC

Sub-Panel Feeder & Wire Sizing Calculator

Detached garage, workshop, shed, or basement sub-panel installations.

A_cmil = (2 × K × I × L) / ΔV_allowed Open →

Electrician Trade & NEC

Home Generator Sizing & Transfer Switch Calculator

Homeowners preparing for power outages and storm backup.

Total Required kW = [Σ Essential Running Watts + Max Starting Surge Watt] × 1.20 Open →

Electrician Trade & NEC

EV Charging Station Circuit & Wire Sizing Calculator

Electric vehicle owners installing home Level 2 chargers for Tesla, Rivian, Ford, Hyundai, etc.

Breaker Amps = Continuous Charge Amps × 1.25 Open →

Electrician Trade & NEC

Grounding Electrode Conductor (GEC) Sizing Calculator (NEC 250.66)

Main electrical service entrance installations and service upgrades.

Lookup per NEC Table 250.66 based on largest ungrounded service-entrance conductor area Open →

Electrician Trade & NEC

Equipment Grounding Conductor (EGC) Sizing Calculator (NEC 250.122)

Branch circuit wiring, grounding motors, sub-panels, and machinery.

Lookup per NEC Table 250.122 based on circuit overcurrent protective device (fuse or breaker) Open →

Electrician Trade & NEC

Maximum Wire Distance Calculator for Fixed Voltage Drop

Planning outdoor lighting, driveway gates, shed feeds, and detached garage circuits.

L_max = (ΔV_max × A_cmil) / (2 × K × I) (1-Phase) Open →

Electrician Trade & NEC

Three-Phase Voltage Drop Calculator (Balanced Feeder)

Commercial building electrical design, manufacturing plant motor feeder sizing.

ΔV = (√3 × I × L × R_conductor) / 1000 Open →

Electrician Trade & NEC

Resistor Color Code 4-Band, 5-Band & 6-Band Calculator

Electronics hobbyists, breadboard prototyping, circuit board repair technicians.

R = (D1 × 10 + D2) × 10^Multiplier ± Tolerance % Open →

Electrician Trade & NEC

SMD Resistor Code Calculator (3-Digit, 4-Digit, EIA-96)

PCB reverse engineering, smartphone and laptop motherboard micro-soldering.

3-Digit: (AB) × 10^C Open →

Electrician Trade & NEC

LED Current Limiting Series Resistor Calculator

Arduino, Raspberry Pi, custom automotive lighting, DIY electronics projects.

R = (V_supply - [N × V_forward]) / I_led Open →

Watts-to-Amps Values

100 Watts to Amps Calculator

100W solar panels, laptop chargers, audio equipment.

I = 100 / (V × PF) Open →

Watts-to-Amps Values

300 Watts to Amps Calculator

Portable power stations (Jackery/EcoFlow), gaming PCs, residential solar panels.

I = 300 / (V × PF) Open →

Watts-to-Amps Values

500 Watts to Amps Calculator

Small power inverters, halogen work lights, desktop workstations.

I = 500 / (V × PF) Open →

Watts-to-Amps Values

1000 Watts to Amps Calculator

Microwave ovens, small generators, electric cooktops, vacuum cleaners.

I = 1000 / (V × PF) Open →

Watts-to-Amps Values

1200 Watts to Amps Calculator

Hair dryers, countertop toaster ovens, window air conditioners.

I = 1200 / (V × PF) Open →

Watts-to-Amps Values

1500 Watts to Amps Calculator

Portable electric space heaters, electric kettles, pressure washers.

I = 1500 / (V × PF) = 12.5 Amps at 120V Open →

Watts-to-Amps Values

1800 Watts to Amps Calculator

Heavy power tools, induction burners, commercial blenders.

I = 1800 / 120V = 15.0 Amps (100% max capacity of 15A breaker) Open →

Watts-to-Amps Values

2000 Watts to Amps Calculator

2000W portable inverter generators (Honda EU2200i), RV inverters, large heaters.

I = 2000 / (V × PF) = 16.67A at 120V Open →

Watts-to-Amps Values

2400 Watts to Amps Calculator

Heavy shop tools, table saws, Level 1 EVSE max draw.

I = 2400 / 120V = 20.0 Amps Open →

Watts-to-Amps Values

3000 Watts to Amps Calculator

3000W RV inverters, 3kW generators, small water heaters.

I = 3000 / (V × PF) = 250A at 12V Open →

Watts-to-Amps Values

4000 Watts to Amps Calculator

Electric water heaters, medium portable generators, commercial kitchen warmers.

I = 4000 / 120V = 33.3A Open →

Watts-to-Amps Values

5000 Watts to Amps Calculator

5000W dual-fuel generators, 5kW water heaters, garage unit heaters.

I = 5000 / 120V = 41.67A Open →

Watts-to-Amps Values

7500 Watts to Amps Calculator

7500W whole-house portable generators, large electric sauna heaters.

I = 7500 / 240V = 31.25 Amps Open →

Watts-to-Amps Values

10000 Watts to Amps Calculator (10kW to Amps)

10kW residential standby generators, central heat pump auxiliary electric heat strips.

1-Phase: I = 10000 / 240V = 41.67A Open →

Amps-to-Watts Extended

0.5 Amps to Watts Calculator

USB port output, microcontroller sensor loops, LED bulb current draw.

W = 0.5 × V Open →

Amps-to-Watts Extended

2 Amps to Watts Calculator

USB charging adapters, small 12V exhaust fans, CCTV security systems.

W = 2 × V Open →

Amps-to-Watts Extended

3 Amps to Watts Calculator

Laptop USB-C Power Delivery, automotive auxiliary sockets, stereo receivers.

W = 3 × V Open →

Amps-to-Watts Extended

8 Amps to Watts Calculator

Level 1 EVSE low charging mode, small handheld power tools.

W = 8 × V Open →

Amps-to-Watts Extended

12 Amps to Watts Calculator

Continuous appliance threshold, Level 1 standard EV charging cords.

W = 12 × 120V = 1440 Watts (Official 80% continuous limit of a 15A breaker) Open →

Amps-to-Watts Extended

16 Amps to Watts Calculator

Level 2 16A portable EV chargers (NEMA 6-20 outlet), large air compressors.

W = 16 × 120V = 1920W Open →

Amps-to-Watts Extended

25 Amps to Watts Calculator

Commercial food equipment, heavy RV 30A continuous loads.

W = 25 × V (12V = 300W, 120V = 3000W, 240V = 6000W) Open →

Amps-to-Watts Extended

32 Amps to Watts Calculator

Tesla Mobile Connector, 32A Level 2 home EV charging stations.

W = 32 × 240V = 7680 Watts (7.68 kW) Open →

Amps-to-Watts Extended

48 Amps to Watts Calculator

Tesla Wall Connector, ChargePoint Home Flex 48A hardwired EV chargers.

W = 48 × 240V = 11520 Watts (11.52 kW) Open →

Amps-to-Watts Extended

70 Amps to Watts Calculator

Heavy garage sub-panels, dual-engine marine shore power.

W = 70 × 240V = 16800 Watts (16.8 kW) Open →

Amps-to-Watts Extended

80 Amps to Watts Calculator

Ford Charge Station Pro (F-150 Lightning bi-directional power), 100A sub-panel continuous capacity.

W = 80 × 240V = 19200 Watts (19.2 kW) Open →

Amps-to-Watts Extended

200 Amps to Watts Calculator

Whole-house load calculations for heat pump additions, solar interconnection sizing.

W = 200 × 240V = 48000 Watts (48.0 kW) Open →

Appliance & HVAC

Space Heater Amps to Watts & Circuit Load Calculator

Winter safety guide, preventing nuisance tripping in residential bedrooms and home offices.

Current = Heater Watts / 120V Open →

Appliance & HVAC

Electric Water Heater Sizing & Circuit Calculator

Plumbing and electrical replacement, water heater upgrades.

Amps = Element Watts / 240V Open →

Appliance & HVAC

RV Electrical Load & Shore Power Capacity Calculator (30A vs 50A)

RV owners camping at campgrounds, preventing pedestal breaker trips.

30A Service: 30A × 120V = 3600W max Open →

Appliance & HVAC

Welder Amps to Watts & Duty Cycle Sizing Calculator

Home garage workshops, fabrication shop electrical installation.

I_effective = I_max × √(Duty Cycle % / 100) per NEC Article 630 Open →

Appliance & HVAC

Hot Tub & Spa Circuit Sizing Calculator

Homeowners purchasing hot tubs, electrician quote preparation.

Total Watts = Heater Watts + (Pump HP × 746 / η) Open →

Appliance & HVAC

Sump Pump & Well Pump Surge Sizing Calculator

Basement flood prevention, emergency power sizing.

Running W = HP × 746 / (η × PF) Open →

Appliance & HVAC

EV Charging Time & Miles-per-Hour Added Calculator

EV drivers planning overnight charging schedules and road trips.

Charging kW = (V × A × 0.90) / 1000 Open →

Appliance & HVAC

Dishwasher & Kitchen Branch Circuit Load Calculator

Kitchen remodeling, electrical rough-in planning.

Total Watts = Motor Running W + Internal Booster Heating Element W (≈ 1200W - 1800W) Open →

Appliance & HVAC

Washing Machine & Clothes Dryer Dual Load Calculator

Home electrical rough-in, laundry appliance upgrades.

Washer (120V 15A = ~500W-1200W) + Dryer (240V 30A = ~5000W-6000W) Open →

Appliance & HVAC

Shop Air Compressor Amps to Watts & Surge Sizing Calculator

Automotive garage setup, woodworker workshop electrical planning.

Running Watts = HP × 746 / η Open →

Energy Cost & Bill

Electricity Cost Calculator (Watts/kWh to Dollar Cost)

Home budgeting, identifying high-energy-cost appliances.

Cost ($) = (Watts × Hours_per_day × 30 / 1000) × ($/kWh Rate) Open →

Energy Cost & Bill

Whole-House Appliance Energy Audit Calculator

Lowering household electricity bills, DIY home energy auditing.

Monthly kWh = Σ [(Watts_i × Hours_i × Qty_i × 30) / 1000] Open →

Energy Cost & Bill

Phantom Load / Standby Power Vampire Draw Calculator

Sustainability education, smart power strip ROI calculation.

Annual Cost ($) = Σ (Standby Watts_i × 8760 hrs / 1000) × ($/kWh Rate) Open →

Energy Cost & Bill

LED vs Incandescent / Halogen Energy Savings Calculator

Home energy efficiency upgrades, commercial LED lighting retrofits.

Annual Savings ($) = [((Old Watts - LED Watts) × Hours/Day × 365) / 1000] × ($/kWh) × Bulb Count Open →

Energy Cost & Bill

Air Conditioner (AC) Electricity Cost by BTU & SEER2 Rating

Homeowners estimating summer AC bills, evaluating high-efficiency SEER2 HVAC upgrades.

Average Power (Watts) = BTU / SEER2 Open →

Energy Cost & Bill

EV vs Gas Car Fuel Cost Comparison Calculator

Prospective EV buyers calculating total cost of ownership (TCO).

EV Cost/Mile = (kWh per 100 miles / 100) × ($/kWh) Open →

Energy Cost & Bill

Server & Crypto Mining Rig Power Cost Calculator

Home lab enthusiasts, IT infrastructure planners, cryptocurrency miners.

Monthly Cost = (Continuous Watts × 24 hrs × 30.4 days / 1000) × ($/kWh) × PUE (Cooling Factor) Open →

Energy Cost & Bill

Electric Space Heater vs Central Heat Cost Calculator

Home energy savings strategy during peak winter billing months.

Space Heater Cost = (1.5 kW × SpaceHeaterHours) × ($/kWh) Open →