Volt to Amps Calculator

Volts to Amps Calculator – V to A Converter (DC/AC/3-Phase)

Volts to Amps Calculator

Convert voltage (Volts) to current (Amps) using power (Watts) or resistance (Ohms)

Quick Select Common Configurations:
Current
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A (Amperes)
Calculation Steps
Recommended Wire Gauge
AWG (American)
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Metric (mm²)
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* Based on copper wire at 30°C ambient. Consult NEC/local codes for actual installation.
Safety Assessment
Current in Other Units
Milliamperes (mA) —
Microamperes (µA) —
Kiloamperes (kA) —
Calculated Power (W) —
Volt to Amps calculator
Table of Contents

How to Convert Volts to Amps

Converting volts to amps requires knowing either the power (in watts) or the resistance (in ohms) of your circuit. This is because voltage and current are related through Ohm’s Law and the power equation. You cannot directly convert volts to amps with a simple multiplication factor—you need additional circuit information.

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Key Point: Volts measure electrical pressure (potential difference), while Amps measure the flow of electric charge. To find current, you must know either the power consumption or the circuit resistance.

Using Power (Watts) Method

When you know the power consumption of a device, use the power formula to calculate current. This is the most common method for household appliances and electronics.

DC & AC Single Phase Formula
I = P ÷ V
I = Current in Amperes
P = Power in Watts
V = Voltage in Volts

For AC circuits with reactive loads (motors, transformers), you must account for the power factor:

AC Single Phase with Power Factor
I = P ÷ (V × PF)
PF = Power Factor (0 to 1)

Using Resistance (Ohms) Method

When you know the circuit resistance, apply Ohm’s Law directly. This method is essential for circuit design and troubleshooting. Use our Ohm’s Law Calculator for more complex calculations.

Ohm’s Law Formula
I = V ÷ R
I = Current in Amperes
V = Voltage in Volts
R = Resistance in Ohms

Three-Phase Power Calculations

Three-phase systems are common in industrial and commercial applications. The current calculation depends on whether you’re measuring line-to-line or line-to-neutral voltage:

Three-Phase Line-to-Line
I = P ÷ (√3 × VLL × PF)
Three-Phase Line-to-Neutral
I = P ÷ (3 × VLN × PF)
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Pro Tip: For three-phase calculations, line-to-line voltage is √3 (approximately 1.732) times the line-to-neutral voltage. For a 480V L-L system, the L-N voltage is about 277V.

Step-by-Step Calculation Examples

Example 1: DC Circuit with Power

Problem: A 12V LED strip consumes 60 watts. What current does it draw?

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Step 1: Identify values: P = 60W, V = 12V
Step 2: Apply formula: I = P ÷ V
Step 3: Calculate: I = 60 ÷ 12 = 5 Amperes

Example 2: AC Circuit with Power Factor

Problem: A 230V motor rated at 2000W has a power factor of 0.85. What current does it draw?

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Step 1: Identify values: P = 2000W, V = 230V, PF = 0.85
Step 2: Apply formula: I = P ÷ (V × PF)
Step 3: Calculate: I = 2000 ÷ (230 × 0.85) = 2000 ÷ 195.5 = 10.23 Amperes

Example 3: Using Ohm’s Law

Problem: A 24V circuit has a 100Ω resistor. What current flows through it?

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Step 1: Identify values: V = 24V, R = 100Ω
Step 2: Apply Ohm’s Law: I = V ÷ R
Step 3: Calculate: I = 24 ÷ 100 = 0.24 Amperes (240 mA)

Common Voltage to Current Reference Table

This reference table shows typical current draws for common voltage and power combinations. Use our Amps to Watts Calculator for reverse calculations.

ApplicationVoltage (V)Power (W)Current (A)
USB Charger5V10W2.0 A
Car Accessory12V60W5.0 A
Industrial DC24V240W10.0 A
US Household120V1800W15.0 A
EU Household230V2990W13.0 A
Industrial 3-Phase480V (L-L)10,000W14.2 A*

* Three-phase calculation with PF = 0.85

Wire Sizing Based on Current

Selecting the correct wire gauge is critical for safety. Undersized wires can overheat and cause fires. This table shows recommended copper wire sizes based on current capacity at 30°C ambient temperature.

Current (A)AWG (American)Metric (mm²)Typical Use
Up to 7A18 AWG0.75 mm²Light fixtures, small appliances
Up to 10A16 AWG1.0 mm²Extension cords, lamps
Up to 15A14 AWG2.5 mm²Standard outlets (US)
Up to 20A12 AWG4.0 mm²Kitchen outlets, HVAC
Up to 30A10 AWG6.0 mm²Dryers, water heaters
Up to 55A6 AWG16 mm²Electric ranges, EV chargers
Up to 85A4 AWG25 mm²Main service panels
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Safety Warning: Always consult the National Electrical Code (NEC) or your local electrical codes for actual installation requirements. Wire sizing depends on factors including ambient temperature, conduit fill, and insulation type.

Frequently Asked Questions

Q1 Can I convert Volts to Amps directly? +
No, you cannot convert volts to amps directly without additional information. Volts measure electrical potential (pressure), while amps measure current (flow). To find current, you need either:
  • Power in watts: I = P ÷ V
  • Resistance in ohms: I = V ÷ R
This is similar to how you can’t convert pressure to flow rate without knowing the pipe size or restriction.
Q2 What is Power Factor and when do I need it? +
Power factor (PF) is the ratio of real power (watts) to apparent power (VA) in an AC circuit. It ranges from 0 to 1:
  • PF = 1 (unity): Purely resistive loads like heaters and incandescent bulbs
  • PF = 0.8-0.95: Motors, transformers, and inductive loads
  • PF = 0.6-0.8: Older motors and fluorescent lighting
For DC circuits and purely resistive AC loads, you can use PF = 1. For motors and industrial equipment, use the rated power factor from the nameplate.
Q3 Why does three-phase use different formulas? +
Three-phase power delivers electricity through three conductors with voltages 120° out of phase. This creates a more efficient power delivery system. The √3 factor (approximately 1.732) appears because:
  • Line-to-line voltage is √3 times line-to-neutral voltage
  • Total power is distributed across three phases
  • The formula accounts for the phase relationship between conductors
For example, a 480V L-L system has approximately 277V L-N (480 ÷ √3 = 277).
Q4 How do I calculate current for a motor? +
For motors, always use the AC formula with power factor:
  • Single-phase: I = P ÷ (V × PF × Efficiency)
  • Three-phase: I = P ÷ (√3 × V × PF × Efficiency)
Check the motor nameplate for rated power, voltage, power factor, and efficiency. Note that starting current (inrush) can be 5-8 times the running current, which affects circuit breaker and wire sizing.
Q5 What’s the difference between Amps and Amp-Hours? +
Amps (A) measure instantaneous current flow, while Amp-hours (Ah) measure total charge over time:
  • Amps = Current at any moment (like speedometer reading)
  • Amp-hours = Current × Time (like odometer reading)
A 100Ah battery can deliver 10A for 10 hours, 5A for 20 hours, or 1A for 100 hours (theoretically). Use our Amp Hours to Amps Calculator for battery calculations.
Q6 How much current is dangerous? +
Current through the human body can be dangerous at surprisingly low levels:
  • 1 mA: Barely perceptible
  • 5 mA: Mild shock, can let go
  • 10-20 mA: Painful, may not be able to let go
  • 50-100 mA: Potentially fatal (ventricular fibrillation)
  • Over 100 mA: Usually fatal without immediate treatment
Always follow electrical safety practices and never work on live circuits without proper training and equipment.

Explore our suite of electrical calculators for comprehensive circuit analysis and design:

Amps to Volts Calculator Ohm’s Law Calculator Amps to Watts Calculator Kilowatts to Volts Calculator Volts to Kilowatts Calculator
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Author

  • Manish Kumar

    Manish holds a B.Tech in Electrical and Electronics Engineering (EEE) and an M.Tech in Power Systems, with over 10 years of experience in Metro Rail Systems, specializing in advanced rail infrastructure.

    He is also a NASM-certified fitness and nutrition coach with more than a decade of experience in weightlifting and fat loss coaching. With expertise in gym-based training, lifting techniques, and biomechanics, Manish combines his technical mindset with his passion for fitness.

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