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Amps to Volts Calculator

Convert current (amps) to voltage using resistance or power. Calculate voltage using Ohm's Law or power formulas.

Calculate Volts from Amps

Calculation Method

Current (Amps)

Resistance (Ohms Ω)

Results:

Volts (V)120

Millivolts (mV)120,000

Kilovolts (kV)0.12

Formulas

Using Resistance (Ohm's Law)

V(V) = I(A) × R(Ω)

Voltage equals current times resistance

Using Power

V(V) = P(W) ÷ I(A)

Voltage equals power divided by current

Quick Examples

•10A × 12Ω = 120V
•1200W ÷ 10A = 120V
•5A × 2.4Ω = 12V

What Is Amps to Volts Conversion?

Converting amperes to volts requires knowing resistance (Ohm's Law) or power. Using Ohm's Law: V = I × R, where voltage equals current times resistance. Using power: V = P ÷ I, where voltage equals power divided by current. This conversion is fundamental to electrical circuit analysis, troubleshooting, and design. Electricians, electronics technicians, and engineers use these relationships daily to diagnose circuit problems, verify proper operation, and design new systems. Understanding the relationship between voltage, current, and resistance is the foundation of all electrical engineering.

How to Calculate Amps to Volts Conversion

1
Choose Conversion Method
Select Ohm's Law method (using resistance) if you know the circuit resistance, or the Power method if you know the power consumption in watts.
2
Enter Current in Amps
Input the measured current using an ammeter or clamp meter. Ensure the meter is properly rated for the circuit voltage and current levels.
3
Enter Resistance or Power
For Ohm's Law: enter resistance in ohms (Ω). For the power method: enter power in watts (W). Check component specifications or measure with appropriate instruments.
4
Interpret the Result
The calculated voltage should match expected circuit values. Significant deviations indicate potential issues: excessive voltage drop, faulty components, or measurement errors.

Why Amps to Volts Conversion Matters

Circuit Troubleshooting

Calculating expected voltage from measured current and known resistance helps identify faulty components, excessive voltage drops, and wiring problems in electrical circuits.

Voltage Drop Verification

By measuring current and knowing conductor resistance, you can calculate voltage drop across cables. This verifies compliance with NEC voltage drop recommendations (3% branch, 5% total).

Component Selection

Knowing the voltage across components from current and resistance values helps select appropriately rated parts — resistors, capacitors, semiconductors, and insulation materials.

Safety Assessment

Calculating voltage from current and resistance helps verify that exposed surfaces remain at safe voltage levels, supporting electrical safety per OSHA and NFPA 70E standards.

Electrical Safety Tips & Best Practices

Verify with Direct Measurement

Whenever possible, verify calculated voltage with a direct voltmeter measurement. Discrepancies may reveal non-linear components, temperature effects, or measurement errors.

Temperature Affects Resistance

Conductor resistance increases with temperature. Copper increases about 0.393% per degree Celsius. Hot wiring has higher resistance and greater voltage drop than cold calculations predict.

Use RMS Values for AC

For AC circuits, use RMS (root mean square) current values, not peak values. Most meters read RMS by default. RMS values give equivalent DC heating effect for accurate power calculations.

Check Wire Gauge Resistance

Common conductor resistances per 1000 feet: 14 AWG = 2.525Ω, 12 AWG = 1.588Ω, 10 AWG = 0.999Ω. Use these to calculate voltage drop in long cable runs.

Amps to Volts Conversion Table (by Resistance)

Current	@ 1Ω	@ 10Ω	@ 100Ω	@ 1000Ω
1A	1V	10V	100V	1000V
5A	5V	50V	500V	5000V
10A	10V	100V	1000V	10000V
15A	15V	150V	1500V	15000V
20A	20V	200V	2000V	20000V

Frequently Asked Questions

How do I convert amps to volts?

You need either the resistance (using Ohm's Law: V = I×R) or the power (using V = P/I). Current alone cannot be converted to voltage without additional information.

What is the relationship between amps and volts?

Amps (current) and volts (voltage) are related through resistance and power. Higher voltage with the same resistance means higher current. They are connected by Ohm's Law (V = I × R).

Can I convert amps to volts without knowing resistance?

You need either resistance (V = I × R) or power (V = P ÷ I) to convert amps to volts. Current alone cannot determine voltage — they are independent electrical quantities that are related through resistance or power.

What is Ohm's Law?

Ohm's Law states that voltage equals current multiplied by resistance: V = I × R. Discovered by Georg Simon Ohm in 1827, it is the most fundamental relationship in electrical engineering. It applies to DC circuits and to AC circuits when using impedance instead of pure resistance.

How do I find resistance if I know amps and volts?

Rearrange Ohm's Law: R = V ÷ I. For example, if a circuit has 12V across it and 2A flowing through it, the resistance is 6Ω. This is useful for identifying unknown resistors or detecting insulation degradation.

What is the voltage across a 100-ohm resistor with 0.5A?

Using Ohm's Law: V = 0.5A × 100Ω = 50V. The resistor dissipates P = V × I = 50V × 0.5A = 25W. Ensure the resistor is rated for at least 25W to prevent overheating and failure.

Does Ohm's Law work for AC circuits?

Yes, but for AC circuits, resistance is replaced by impedance (Z), which includes resistance (R), inductive reactance (XL), and capacitive reactance (XC). The formula becomes V = I × Z. For purely resistive AC loads, Ohm's Law applies directly.

Related Electrical Calculators

⚡Volts to Amps ⚡Amps to Watts ⚡Ohm's Law ⚡Voltage

References & Industry Standards

IEEE 100 - The Authoritative Dictionary of IEEE Standards Terms
NEC Chapter 3 - Wiring Methods and Materials
IEC 60038 - IEC Standard Voltages
NFPA 70E - Standard for Electrical Safety in the Workplace

Last updated: 2026-02-01 | Reviewed by UnitTables Engineering Team

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What Is Amps to Volts Conversion?

How to Calculate Amps to Volts Conversion

Choose Conversion Method

Select Ohm's Law method (using resistance) if you know the circuit resistance, or the Power method if you know the power consumption in watts.

Enter Current in Amps

Input the measured current using an ammeter or clamp meter. Ensure the meter is properly rated for the circuit voltage and current levels.

Enter Resistance or Power

For Ohm's Law: enter resistance in ohms (Ω). For the power method: enter power in watts (W). Check component specifications or measure with appropriate instruments.

Interpret the Result

The calculated voltage should match expected circuit values. Significant deviations indicate potential issues: excessive voltage drop, faulty components, or measurement errors.

Why Amps to Volts Conversion Matters

Circuit Troubleshooting

Calculating expected voltage from measured current and known resistance helps identify faulty components, excessive voltage drops, and wiring problems in electrical circuits.

Voltage Drop Verification

By measuring current and knowing conductor resistance, you can calculate voltage drop across cables. This verifies compliance with NEC voltage drop recommendations (3% branch, 5% total).

Component Selection

Knowing the voltage across components from current and resistance values helps select appropriately rated parts — resistors, capacitors, semiconductors, and insulation materials.

Safety Assessment

Calculating voltage from current and resistance helps verify that exposed surfaces remain at safe voltage levels, supporting electrical safety per OSHA and NFPA 70E standards.

Electrical Safety Tips & Best Practices

Verify with Direct Measurement

Whenever possible, verify calculated voltage with a direct voltmeter measurement. Discrepancies may reveal non-linear components, temperature effects, or measurement errors.

Temperature Affects Resistance

Conductor resistance increases with temperature. Copper increases about 0.393% per degree Celsius. Hot wiring has higher resistance and greater voltage drop than cold calculations predict.

Use RMS Values for AC

For AC circuits, use RMS (root mean square) current values, not peak values. Most meters read RMS by default. RMS values give equivalent DC heating effect for accurate power calculations.

Check Wire Gauge Resistance

Common conductor resistances per 1000 feet: 14 AWG = 2.525Ω, 12 AWG = 1.588Ω, 10 AWG = 0.999Ω. Use these to calculate voltage drop in long cable runs.

Current

@ 1Ω

@ 10Ω

@ 100Ω

@ 1000Ω

10V

100V

1000V

50V

500V

5000V

10A

10V

100V

1000V

10000V

15A

15V

150V

1500V

15000V

20A

20V

200V

2000V

20000V