Amperage Calculator

Calculate electrical current for DC and AC circuits

๐Ÿ”‹

Amperage Calculator

Calculate electrical current (amperage) from voltage, power, or resistance. Use this calculator to determine amps for circuit breakers, wire sizing, and electrical safety planning.

๐Ÿ”‹ Amperage Calculator

๐Ÿ“Š Results

Current (Amperage)
12 A
Voltage
120 V
Resistance
10 ฮฉ
Power
1,440 W
Circuit Type
DC

Formula Used

I = V / R
Current equals Voltage divided by Resistance

Calculation Steps

๐Ÿ“ Wire Size Reference (AWG)

Based on the calculated amperage, here is a recommended wire gauge:

AWG Max Amps (Copper) Typical Use
14 AWG15 ALighting, small appliances
12 AWG20 AKitchen, bathroom circuits
10 AWG30 ADryers, AC units
8 AWG40 ARanges, large AC
6 AWG55 ASubpanels, large appliances
4 AWG70 AService entrance
2 AWG95 AService entrance, feeders
1/0 AWG125 AMain service

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๐Ÿ“š Understanding Amperage

What is Amperage?

Amperage (or current) is the rate of flow of electric charge through a conductor. Measured in amperes (A), it represents how many electrons pass a given point per second. One ampere equals one coulomb of charge per second.

DC vs AC Current

DC (Direct Current) flows in one direction. AC (Alternating Current) periodically reverses direction. For AC circuits, the power factor must be considered โ€” it represents the efficiency of power delivery due to the phase difference between voltage and current.

Why Amperage Matters

Knowing the amperage is essential for selecting proper wire sizes, circuit breakers, and fuses. Too much current through undersized wiring creates heat and can cause fires โ€” a key reason electrical codes exist.

Amperage Formulas

DC Circuits

I = V / R

Amps = Volts รท Ohms

I = P / V

Amps = Watts รท Volts

I = โˆš(P / R)

Amps = โˆš(Watts รท Ohms)

AC Single-Phase

I = P / (V ร— PF)

Amps = Watts รท (Volts ร— Power Factor)

I = V / R

Same as DC for resistive loads

AC Three-Phase

I = P / (โˆš3 ร— V ร— PF)

Three-phase power formula

I = V / R

Per-phase current for resistive loads

Common Appliance Amperage

Appliance Typical Watts Amps (at 120V)
LED Light Bulb10 W0.08 A
Laptop Computer50 W0.42 A
Refrigerator150 W1.25 A
Microwave Oven1,000 W8.33 A
Hair Dryer1,500 W12.5 A
Space Heater1,500 W12.5 A
Electric Oven3,000 W25 A