Convert between 40+ electrical units including Amps, Volts, Watts, kWh, kVA, Joules and more
Enter any 3 values above and click Calculate to see detailed steps.
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Faiq Ur Rahman is a web designer, digital product developer, and founder of Toolraxy, a growing platform of web-based calculators and utility tools. He specializes in building structured, user-friendly tools focused on health, finance, productivity, and everyday problem-solving.
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The Electrical Calculator is a comprehensive free online tool that performs over 40 electrical unit conversions and calculations. Whether you’re an electrician sizing circuits, an engineer designing systems, a student learning electrical principles, or a homeowner calculating energy usage, this tool provides instant, accurate results. Convert between Amps, Volts, Watts, kilowatt-hours (kWh), kilovolt-amps (kVA), Volt-amps (VA), Joules, milliamp-hours (mAh), and more. The 4-in-1 Ohm’s Law calculator solves for any missing value when you input three known parameters, while specialized calculators handle power factor, three-phase systems, and battery capacity conversions.
Select Calculation Type: Browse the left sidebar categories—Most Popular, Amps Conversions, Power Conversions, Energy & Battery, Volts & Joules, and Watts & Joules. Click any calculator to select it.
Use Search: Type keywords like “amps to watts” or “kWh” in the search box to quickly find specific calculators.
Enter Values: Input your known values in the provided fields. For the 4-in-1 Ohm’s Law calculator, enter any three values to calculate the fourth.
Set Options: Configure additional parameters like Power Phase (Single Phase, Three Phase, DC) and Power Factor (0–1) where applicable.
Click Calculate: Press the Calculate button to see your result with the appropriate unit.
View Detailed Steps: Review the formula used and the step-by-step calculation process displayed below the result.
Use Example Button: Click the lightbulb icon to load example values for the selected calculator type.
Clear All: Use the Clear button to reset all input fields for a new calculation.
The Electrical Calculator contains a comprehensive configuration object with 40+ individual calculators, each containing input definitions, options, and calculation logic. Here’s how each type works:
Ohm’s Law: The foundation of electrical calculations
V = I × R (Voltage = Current × Resistance)
I = V ÷ R (Current = Voltage ÷ Resistance)
R = V ÷ I (Resistance = Voltage ÷ Current)
P = V × I (Power = Voltage × Current)
Power Formulas:
DC Power: P = V × I
Single Phase AC: P = V × I × PF (Power Factor)
Three Phase AC: P = V × I × √3 × PF
Energy Formulas:
kWh = (Watts × Hours) ÷ 1000
Joules = Watts × Seconds
Wh = (mAh × V) ÷ 1000
4-in-1 Watts, Volts, Amps, Ohms Calculator:
Enter any three values (Power, Voltage, Current, Resistance)
Tool calculates the missing fourth value
Automatically applies Ohm’s Law and Power Law combinations
Supports Single Phase, Three Phase (√3 factor), and DC configurations
Phase factor: Single Phase = 1, Three Phase = 1.732, DC = 1
Amps Conversions:
Amps to kW: I × V × PF ÷ 1000 (with phase factor)
Amps to kVA: I × V ÷ 1000 (apparent power)
Amps to VA: I × V (apparent power)
Amps to Volts: P ÷ I (using power)
Amps to Watts: I × V × PF
kVA Conversions:
kVA to Amps: (kVA × 1000) ÷ (V × phase factor)
kVA to Watts: kVA × 1000 × PF
kVA to kW: kVA × PF
kVA to VA: kVA × 1000
kW Conversions:
kW to Amps: (kW × 1000) ÷ (V × PF × phase factor)
kW to Volts: (kW × 1000) ÷ (I × PF × phase factor)
kW to kWh: kW × hours
kW to VA: (kW × 1000) ÷ PF
kW to kVA: kW ÷ PF
Energy & Battery Conversions:
kWh to kW: kWh ÷ hours
kWh to Watts: (kWh × 1000) ÷ hours
mAh to Wh: (mAh × V) ÷ 1000
Wh to mAh: (Wh × 1000) ÷ V
Volts & Joules Conversions:
Volts to Amps: P ÷ (V × PF × phase factor)
Volts to Watts: V × I × PF × phase factor
Volts to kW: (V × I × PF × phase factor) ÷ 1000
Volts to Joules: V × C (Charge in Coulombs)
Volts to eV: Direct conversion (1V = 1eV per Coulomb)
Watts & Joules Conversions:
Watts to Amps: P ÷ (V × PF × phase factor)
Watts to Joules: P × time (seconds)
Watts to kWh: (P × hours) ÷ 1000
Watts to Volts: P ÷ (I × PF × phase factor)
Watts to VA: P ÷ PF
Watts to kVA: P ÷ (PF × 1000)
Joules to Watts: J ÷ time
Joules to Volts: J ÷ C (Charge in Coulombs)
The 4-in-1 calculator enforces a strict “exactly 3 values” rule:
If fewer than 3 values are entered: Error message displayed
If all 4 values are entered: Error message displayed
Only when exactly 3 values have positive numbers does calculation proceed
Let’s walk through a practical example using the 4-in-1 calculator.
Scenario: You’re installing a 240V air conditioner that draws 12.5 amps. You need to determine the power consumption in watts and ensure your circuit breaker is properly sized.
Step 1: Select “Watts, Volts, Amps, Ohms” from Most Popular.
Step 2: Set Power Phase to “Single Phase (Residential)”.
Step 3: Enter the known values:
Voltage: 240 V
Current: 12.5 A
Resistance: (leave blank)
Power: (leave blank)
Step 4: Click Calculate.
Result: The calculator determines Power = 240V × 12.5A = 3000 Watts
Calculation Steps:
Power = V × I Power = 240V × 12.5A = 3000W
Interpretation: The air conditioner requires 3000 watts (3 kW) of power. At 240V, this draws 12.5 amps, meaning a 20-amp circuit breaker would provide adequate capacity (80% of 20A = 16A safe continuous load).
Electrical units measure fundamental properties of electricity: voltage (electrical pressure), current (flow rate), resistance (opposition to flow), and power (rate of energy transfer). Understanding these units and their relationships is essential for safe electrical design, energy management, and troubleshooting.
Voltage (Volts – V): Electrical potential difference—the “pressure” that pushes electrons through a circuit. Household outlets typically provide 120V (North America) or 230V (Europe, Asia). Higher voltage allows more power delivery with less current.
Current (Amps – A): The flow rate of electrical charge—how many electrons pass a point per second. Current determines wire size requirements; higher currents need thicker wires to prevent overheating.
Resistance (Ohms – Ω): Opposition to current flow. Conductors have low resistance (allowing current), insulators have high resistance (blocking current). Resistance causes voltage drop and heat generation.
Power (Watts – W): The rate of energy consumption or production. Light bulbs, motors, and appliances are rated in watts. 1000 watts = 1 kilowatt (kW).
Energy (kWh, Joules): Total work done over time. Kilowatt-hours measure electrical energy for billing—a 1000W device running for 1 hour consumes 1 kWh. Joules are the SI unit of energy (1 watt × 1 second).
Apparent Power (VA, kVA): In AC circuits, voltage and current may be out of phase. VA measures the product of voltage and current regardless of phase. kVA = VA ÷ 1000.
Power Factor (PF): The ratio of real power (Watts) to apparent power (VA), ranging from 0 to 1. Resistive loads (heaters, incandescent lights) have PF = 1. Inductive loads (motors, transformers) have PF < 1 (typically 0.8–0.9).
Three-Phase Power: Industrial systems use three-phase power with voltage between phases multiplied by √3 (1.732). Three-phase allows more efficient power transmission and motor operation.
Circuit Sizing: Overloaded circuits cause fires. Calculate current from power and voltage to select appropriate wire gauge and breaker size (National Electrical Code requires circuits loaded to no more than 80% of breaker rating for continuous loads).
Energy Cost Calculation: Convert appliance wattage and usage hours to kWh to estimate electricity bills. A 1500W space heater running 8 hours daily consumes 12 kWh per day.
Battery Selection: Convert between mAh (battery capacity rating) and Wh (actual energy) using voltage. A 5000mAh power bank at 3.7V stores 18.5Wh—enough to charge a phone with a 10Wh battery approximately 1.8 times.
Generator Sizing: Convert kVA to kW using power factor. A 10kVA generator with 0.8 PF can supply 8kW of real power—essential knowledge when connecting motor loads.
Transformer Selection: Calculate kVA requirements from load watts and power factor. A 5kW motor load with 0.8 PF requires a 6.25kVA transformer.
Voltage Drop Calculations: Using resistance (Ohms) and current to calculate voltage drop over distance ensures equipment receives adequate voltage.
Residential:
Sizing solar panel systems (kW to kWh)
Estimating appliance operating costs
Selecting extension cord gauges
Understanding electric vehicle charging rates
Commercial:
Load calculations for building electrical services
Transformer sizing
Power factor correction decisions
Generator sizing for backup power
Industrial:
Motor current calculations for starter selection
Three-phase load balancing
Harmonic analysis preparation
Energy efficiency audits
Electronics:
Power supply selection (Volts × Amps)
Battery life calculations (mAh to hours)
LED resistor sizing (Ohm’s Law)
PCB trace width calculations
40+ Calculators: Comprehensive coverage from basic Ohm’s Law to specialized battery and energy conversions
Phase Support: Single-phase, three-phase (√3 factor), and DC options for accurate AC calculations
Power Factor Integration: Automatic inclusion of PF in AC power calculations
Step-by-Step Solutions: Shows formulas and calculation steps for learning and verification
4-in-1 Functionality: Enter any three values to find the fourth using Ohm’s Law combinations
Error Prevention: Validation ensures exactly three values for 4-in-1 calculator
Example Values: One-click loading of realistic examples for each calculator type
Search Function: Quickly find specific calculators among 40+ options
Mobile Responsive: Categorized sidebar collapses on mobile for easy navigation
Instant Results: No page reloads—calculations happen immediately
No Registration: Free to use with no account required
Educational Value: Learn electrical relationships while calculating
The tool includes over 40 individual calculators covering Amps, Volts, Watts, kWh, kVA, VA, Joules, mAh, Wh, and eV conversions in various combinations.
Select “Three Phase (Industrial)” from the Power Phase dropdown. The calculator automatically applies the √3 (1.732) factor to all relevant formulas.
Power factor (PF) represents the efficiency of AC power usage. Use PF = 1 for purely resistive loads (heaters, incandescent lights). Use PF = 0.8–0.9 for motor loads, transformers, and fluorescent lighting.
Yes, use “mAh to Wh” to convert milliamp-hours to watt-hours, or “Wh to mAh” for the reverse. Both require voltage input for accurate conversion.
Use “kWh to Watts” calculator. Enter energy in kWh and time in hours. Formula: Watts = (kWh × 1000) ÷ hours.
kVA measures apparent power (voltage × current), while kW measures real power (actual work done). kW = kVA × power factor. Generators and transformers are rated in kVA; actual usable power depends on load power factor.
Use “kW to kWh” or “Watts to kWh” to find energy consumption, then multiply by your electricity rate ($/kWh). Example: 1500W for 5 hours = 7.5 kWh × $0.12 = $0.90.
Single-phase uses two wires (120/240V residential). Three-phase uses three or four wires (208/480V industrial) with voltage between phases multiplied by √3, allowing more power with smaller conductors.
Yes, select “DC (Direct Current)” from the Power Phase dropdown. This sets phase factor = 1 and ignores power factor (which doesn’t apply to DC).
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