Amps to Volts Calculator
Convert current to voltage using Ohm's Law or Watt's Law
What is an Amps to Volts Calculator?
The Amps to Volts Calculator is a free online tool that converts current (A) to voltage (V) using either Ohm's Law (when resistance is known) or Watt's Law (when power is known). You cannot convert amps to volts directly — they measure different electrical properties. Amps measure the rate of electron flow, while volts measure the electrical pressure driving that flow. You always need a second value: either resistance (Ω) or power (W). This calculator supports both methods with AC power factor adjustment.
When to Use Ohm's Law vs Watt's Law?
Use Ohm's Law (V = I × R) when you know the resistance of the circuit — common when working with resistors, wire calculations, or measured resistance values. Use Watt's Law (V = P ÷ I) when you know the power rating and current — common when troubleshooting circuits where you can measure current with a clamp meter and know the device's power rating. Both methods give the same result if all values are consistent.
Understanding Ohm's Law & Watt's Law
Amps to Volts using Resistance (Ohm's Law)
V = I × R — multiply current by resistance to get voltage
Ohm's Law states that voltage equals current multiplied by resistance: V(V) = I(A) × R(Ω). This is the most direct way to find voltage when you know how much current flows through a known resistance. The result tells you the voltage drop across that resistance.
5 A through a 24 Ω resistor: V = 5 × 24 = 120 V. 2 A through a 6 Ω wire resistance: V = 2 × 6 = 12 V voltage drop.
Amps to Volts using Power (Watt's Law)
V = P ÷ I — use when power rating is known
Watt's Law rearranged gives voltage: V(V) = P(W) ÷ I(A). For AC circuits with a power factor: V = P ÷ (I × PF). This method is used when you know the device's power consumption and current draw.
A 600 W device drawing 5 A: V = 600 ÷ 5 = 120 V. A 2400 W appliance drawing 10 A: V = 2400 ÷ 10 = 240 V.
Example Calculations
Step-by-step amps to volts conversion examples
Using Ohm's Law (Resistance Known)
Given: Current (I) = 10 A, Resistance (R) = 12 Ω
Using Watt's Law (Power Known)
Given: Current (I) = 20 A, Power (P) = 4800 W
AC with Power Factor
Given: Current (I) = 10 A, Power (P) = 1020 W, PF = 0.85
Amps to Volts Conversion Chart
Quick reference for common current and resistance combinations
| Current (A) | Resistance (Ω) | Voltage (V) |
|---|---|---|
| 1 A | 6 Ω | 6 V |
| 1 A | 12 Ω | 12 V |
| 1 A | 24 Ω | 24 V |
| 2 A | 6 Ω | 12 V |
| 2 A | 12 Ω | 24 V |
| 2 A | 24 Ω | 48 V |
| 5 A | 6 Ω | 30 V |
| 5 A | 12 Ω | 60 V |
| 5 A | 24 Ω | 120 V |
| 10 A | 6 Ω | 60 V |
| 10 A | 12 Ω | 120 V |
| 10 A | 24 Ω | 240 V |
| 15 A | 6 Ω | 90 V |
| 15 A | 12 Ω | 180 V |
| 15 A | 24 Ω | 360 V |
| 20 A | 6 Ω | 120 V |
| 20 A | 12 Ω | 240 V |
| 20 A | 24 Ω | 480 V |
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Watts to Volts Calculator
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Convert energy between watt-seconds, watt-hours, and electron volts (eV).
Volts to Watts Calculator
Convert voltage (V) to power (W) for DC, AC single-phase, and AC three-phase circuits.
Watts to Amps Calculator
Convert power (W) to current (A) for DC and AC circuits with power factor support.
Amps to Watts Calculator
Convert current (A) to power (W) for DC, AC single-phase, and AC three-phase circuits.
Volts to Amps Calculator
Convert voltage (V) to current (A) using Ohm's Law or Watt's Law.
Amps to Volts Calculator
Convert current (A) to voltage (V) using Ohm's Law or Watt's Law.
Frequently Asked Questions
How many volts is 10 amps?
10 amps equals different voltages depending on the resistance or power. With 12 Ω resistance: V = 10 × 12 = 120 V. With 24 Ω resistance: V = 10 × 24 = 240 V. With 1200 W power: V = 1200 ÷ 10 = 120 V. You need resistance or power to calculate volts from amps.
How to convert amps to volts?
Two methods: (1) Ohm's Law — multiply amps by resistance: V = I × R. (2) Watt's Law — divide power by amps: V = P ÷ I. For example, 5 A × 24 Ω = 120 V, or 600 W ÷ 5 A = 120 V. You need either resistance or power as a second value.
What is the amps to volts formula?
There are two amps to volts formulas. Ohm's Law: V(V) = I(A) × R(Ω) when resistance is known. Watt's Law: V(V) = P(W) ÷ I(A) when power is known. For AC circuits with power factor: V = P ÷ (I × PF).
How many volts is 15 amps at 100 ohms?
15 amps at 100 ohms equals 1500 volts: V = I × R = 15 × 100 = 1500 V. This is a high voltage — always exercise caution with voltages above 50 V, which can be lethal. High-voltage circuits require specialized equipment and qualified personnel.
Can you convert amps to volts without resistance?
Yes, if you know the power (watts). Use V = P ÷ I. For example, 2400 W ÷ 10 A = 240 V. Without either resistance or power, amps alone cannot determine voltage because the relationship requires a second electrical property.
What is the relationship between amps and volts?
Amps and volts are connected through Ohm's Law: V = I × R. Volts are the electrical pressure (force), amps are the electrical flow (rate), and ohms are the resistance (opposition). More voltage pushes more current through the same resistance. Think of water in a pipe: voltage is the pressure, current (amps) is the flow rate, and resistance is the pipe width.
How does Ohm's Law connect amps and volts?
Ohm's Law states V = I × R (Voltage = Current × Resistance). It shows that voltage and current are directly proportional when resistance is constant — doubling the current doubles the voltage drop. Rearranged: I = V ÷ R (to find current) or R = V ÷ I (to find resistance). Named after Georg Simon Ohm (1827).
How many volts is 20 amps with 1000 watts?
20 amps with 1000 watts equals 50 volts: V = P ÷ I = 1000 ÷ 20 = 50 V. This is a relatively low voltage — common in telecom systems and some industrial control circuits. You can verify: P = V × I = 50 × 20 = 1000 W ✓.