Convert amps to watts instantly. Covers DC, AC single-phase, and 3-phase with power factor. Free tool, no signup, formula shown.
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How to Convert Amps to Watts
To convert amps to watts, multiply amps by volts. This is the core electrical power formula derived from Watt's Law. For AC circuits with motors, compressors, or other inductive loads, multiply the result by the power factor (PF) as well.
DC and resistive loadsWatts = Amps × Volts
Use this formula for batteries (12V, 24V, 48V), solar DC systems, incandescent lamps, resistive heaters, and any load where current and voltage are in phase.
Single-phase ACWatts = Amps × Volts × PF
Use this for 120V or 240V household circuits when the load is a motor, compressor, or other inductive equipment with a known power factor from the nameplate.
Three-phase ACWatts = √3 × Amps × Volts × PF
Use line-to-line voltage (208V, 400V, 480V) for balanced commercial or industrial three-phase systems. The √3 factor equals approximately 1.732.
Premium technical visual
Amps, volts, watts, and circuit limits in one view
Use the diagram as a fast visual map: choose the circuit type, enter measured amps and volts, then compare the watt result with practical circuit limits.
FormulaWatts = Amps x Volts
Amps to Watts CalculatorPremium technical visual with real formula values and planning checkpoints.
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Conversion Tables & Values
The following table converts common amperage values into watts at three standard voltages. All values assume a power factor of 1.00 (pure resistive load). For AC inductive loads, multiply each watt value by the equipment's power factor.
Current (Amps)
Power at 12 V
Power at 120 V
Power at 240 V
1 A
12 W
120 W
240 W
2 A
24 W
240 W
480 W
3 A
36 W
360 W
720 W
5 A
60 W
600 W
1,200 W
10 A
120 W
1,200 W
2,400 W
12 A
144 W
1,440 W
2,880 W
15 A
180 W
1,800 W
3,600 W
20 A
240 W
2,400 W
4,800 W
30 A
360 W
3,600 W
7,200 W
50 A
600 W
6,000 W
12,000 W
For voltages not shown above — such as 220V, 230V, or 480V — use the calculator at the top of this page or visit the dedicated 220V, 230V, or three-phase calculator pages.
f(x)
The Power Formulas
What Is an Amp (Ampere)?
An ampere (symbol: A) is the SI base unit of electric current. It measures the rate at which electric charge flows through a conductor. One ampere equals one coulomb of charge passing a point in one second. In practical terms, amps tell you how much electricity is flowing — think of it as the volume of water moving through a pipe.
The ampere is defined by the International Bureau of Weights and Measures (BIPM) based on the fixed value of the elementary charge. The U.S. National Institute of Standards and Technology (NIST) maintains the reference standard for electrical current measurements.
What Is a Watt?
A watt (symbol: W) is the SI unit of power. It measures the rate of energy transfer or conversion. One watt equals one joule of energy per second. While amps tell you how much current flows, watts tell you how much work that current actually does — how much heat a heater produces, how much light a bulb emits, or how much force a motor delivers.
Named after Scottish inventor James Watt, the unit connects electrical measurements to mechanical and thermal energy. A 100-watt light bulb consumes energy at the rate of 100 joules every second.
The Relationship Between Amps, Volts, and Watts
Amps, volts, and watts are connected by Watt's Law (also called the power equation):
Watt's LawP = I × V
Power (watts) equals current (amps) multiplied by voltage (volts). This is the foundation of every amps-to-watts conversion.
Ohm's Law (related)V = I × R
Voltage equals current times resistance. Combined with Watt's Law, this lets you derive watts from amps and resistance: P = I² × R.
To visualize the relationship, imagine a garden hose: voltage is the water pressure, amps is the flow rate, and watts is the total work the water can do (like spinning a turbine). Higher pressure or higher flow both increase the power output.
DC Amps to Watts Formula
For direct current circuits — batteries, solar panels, automotive systems, LED strips, and electronic power supplies — the conversion is straightforward:
DC formulaP(W) = I(A) × V(V)
No power factor is needed because DC current and voltage are always in phase.
Example: A 12V car battery supplying 10 amps to a winch delivers 10 A × 12 V = 120 watts of power.
AC Single-Phase Amps to Watts Formula
For single-phase alternating current circuits — household outlets (120V in North America, 230V in the UK/EU), appliances, tools — the formula includes power factor:
AC single-phase formulaP(W) = I(A) × V(V) × PF
Power factor accounts for the phase difference between current and voltage in inductive or capacitive loads.
Example: A 120V air conditioner drawing 5 amps with a power factor of 0.85 consumes 5 A × 120 V × 0.85 = 510 watts of real power.
AC Three-Phase Amps to Watts Formula
For three-phase industrial systems — commercial HVAC, large motors, data centers, manufacturing equipment — use the line-to-line voltage formula:
AC three-phase formula (line-to-line)P(W) = √3 × I(A) × VL-L(V) × PF
√3 ≈ 1.732. Use line-to-line voltage (e.g., 208V, 400V, 480V). For line-to-neutral voltage, replace √3 with 3.
Example: A 480V three-phase motor drawing 20 amps per phase with PF 0.88 consumes 1.732 × 20 A × 480 V × 0.88 = 14,633 watts (14.6 kW).
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Step-by-Step Guide
Follow these five steps to convert any amperage reading into watts accurately:
Step 1 — Find the current in amps
Read the current draw from the equipment nameplate, a clamp meter, or the circuit breaker rating. This is your value in amps (A). If the reading is in milliamps (mA), divide by 1,000 to get amps.
Step 2 — Find the voltage
Identify the supply voltage. Common values are 12V (batteries), 120V (US outlets), 220V–240V (US split-phase/international), or 400V–480V (three-phase industrial). Use a multimeter to measure if uncertain.
Step 3 — Determine the circuit type
Is the circuit DC (battery, solar panel, electronics) or AC (wall outlet, motor, HVAC)? For AC, determine if it's single-phase (home) or three-phase (commercial/industrial). This determines which formula to use.
Step 4 — Find the power factor (AC only)
Check the equipment nameplate for PF or cos(φ). Resistive loads (heaters, lamps) have PF ≈ 1.0. Motors and compressors typically range from 0.70 to 0.95. If unknown, use 0.85 as a conservative planning estimate for motor loads.
Step 5 — Multiply using the formula
Apply the correct formula: Watts = Amps × Volts for DC, Watts = Amps × Volts × PF for AC single-phase, or Watts = 1.732 × Amps × Volts × PF for AC three-phase. The result is the real power in watts.
PF
Power Factor Values by Device Type
Power factor is the ratio of real power (watts) to apparent power (volt-amps). It ranges from 0 to 1.00, where 1.00 means all the current drawn is doing useful work. Inductive loads like motors draw extra current that does not produce useful watts, resulting in a lower power factor. The table below lists typical power factor ranges for common electrical equipment.
Device / Load Type
Typical PF
Notes
Resistive heater / incandescent lamp
1.00
Pure resistive load, no reactive component
LED lighting (with driver)
0.90 – 0.99
High-quality LED drivers correct to near unity
Fluorescent lamp (with ballast)
0.85 – 0.95
Electronic ballasts are higher than magnetic
Computer / monitor (SMPS)
0.55 – 0.75
Without active PFC; with PFC can reach 0.95+
Induction motor (full load)
0.80 – 0.90
Drops significantly at partial load
Induction motor (no load)
0.15 – 0.35
Very low PF when running without mechanical load
Air conditioner / heat pump
0.80 – 0.95
Compressor motor with capacitor start
Welding machine (transformer)
0.50 – 0.70
Highly inductive during arc operation
Synchronous motor
0.90 – 1.00
Can be adjusted to lead, lag, or unity
Variable frequency drive (VFD)
0.95 – 0.98
VFD input stage presents near-unity PF to supply
For detailed power factor calculations, capacitor sizing, and kVAR correction, visit the dedicated Power Factor Calculator. To convert apparent power (kVA) to real power (watts), use the kVA to Watts Calculator.
APP
Common Appliance Amps and Watts Chart
The following chart shows typical amperage draw and wattage for common household and commercial appliances. These values represent average running conditions — startup (inrush) current can be 3× to 6× higher for motor-driven equipment. Always check the equipment nameplate for exact ratings.
Appliance
Typical Amps
Voltage
Watts
LED light bulb
0.08 A
120 V
10 W
Ceiling fan
0.5 A
120 V
60 W
Laptop charger
0.5 A
120 V
60 W
Television (55-inch LED)
0.8 A
120 V
95 W
Refrigerator (running)
1.5 A
120 V
180 W
Window air conditioner
5 A
120 V
600 W
Microwave oven
8.3 A
120 V
1,000 W
Hair dryer
12.5 A
120 V
1,500 W
Space heater
12.5 A
120 V
1,500 W
Electric clothes dryer
23 A
240 V
5,500 W
EV charger (Level 2)
32 A
240 V
7,680 W
Central A/C (3 ton)
15 A
240 V
3,600 W
To calculate how many amps your specific appliance draws, divide its wattage by the supply voltage. For example, a 1,500W space heater on a 120V circuit draws 1,500 ÷ 120 = 12.5 amps. To plan your total circuit load, add up all appliance wattages and compare with the breaker safety limits below.
SAFE
Circuit Breaker Safety Check
Once you convert amps to watts, the next step is checking whether the load is safe for the circuit. Breakers are rated in amps, but planning is easier in watts. The National Electrical Code (NEC) Article 210.20 requires that continuous loads (running 3+ hours) must not exceed 80% of the breaker rating unless the breaker and panelboard are specifically listed for 100% continuous duty.
Circuit Breaker
Maximum Watts (PF 1.00)
80% Continuous Planning Limit
15 A breaker
1,800 W at 120 V
1,440 W continuous load
20 A breaker
2,400 W at 120 V
1,920 W continuous load
30 A breaker
3,600 W at 120 V
2,880 W continuous load
40 A breaker
9,600 W at 240 V
7,680 W continuous load
50 A breaker
12,000 W at 240 V
9,600 W continuous load
Practical rule: A 20A breaker on a 120V circuit can handle a maximum of 2,400W, but for continuous loads like a space heater, keep below 1,920W to meet the 80% rule. If your amps-to-watts calculation exceeds these limits, you need a higher-rated circuit, a dedicated branch circuit, or a load redistribution.
Calculator results are educational estimates. Verify final wiring, breaker sizing, conductor derating, voltage-drop limits, and code compliance with a licensed electrician or qualified engineer. Electrical work must comply with local building codes and the applicable edition of the NEC, IEC, or regional wiring regulations.
EX
Amps to Watts Worked Examples
10 amps to watts at 120V
At 120V, 10 amps equals 1,200 watts. Formula: 10 A × 120 V = 1,200 W. This is equivalent to running ten 120W incandescent bulbs simultaneously, or a standard toaster oven.
15 amps to watts at 120V
At 120V, 15 amps equals 1,800 watts. This is the maximum capacity of a standard 15A household circuit. For continuous loads (3+ hours), use the 80% rule: 1,800 × 0.80 = 1,440 watts planning limit.
20 amps to watts at 240V
At 240V, 20 amps equals 4,800 watts. At 120V, the same 20 amps would be only 2,400W. This demonstrates why 240V circuits are used for high-power appliances — they deliver double the wattage at the same amperage.
30 amps to watts at 240V
At 240V, 30 amps equals 7,200 watts. This is a typical electric dryer or small EV charger circuit. The 80% continuous limit is 5,760W.
5 amps to watts at 12V (DC)
At 12V DC, 5 amps equals 60 watts. Formula: 5 A × 12 V = 60 W. This covers common automotive accessories, LED strip lights, and small solar loads.
AC motor: 8 amps at 240V with PF 0.85
For an AC motor with power factor 0.85: 8 A × 240 V × 0.85 = 1,632 watts real power. Without the power factor, you would overestimate at 1,920W — a 15% error that matters for generator and UPS sizing.
DC/AC
DC vs AC Systems
The key difference between DC and AC amps-to-watts conversion is power factor. DC circuits have no reactive power component, so the conversion is a simple multiplication. AC circuits can have reactive power due to inductance (motors, transformers) or capacitance (electronic power supplies), which means the apparent power (VA) is higher than the real power (watts).
To convert watts to amps, divide watts by volts. This is useful when you know an appliance's wattage from its label and need to determine how much current it draws from the circuit:
DCAmps = Watts ÷ Volts
Example: A 60W LED driver on 12V draws 60 ÷ 12 = 5 amps.
AC single-phaseAmps = Watts ÷ (Volts × PF)
Example: A 1,500W heater on 120V at PF 1.0 draws 1,500 ÷ 120 = 12.5 amps.
AC three-phaseAmps = Watts ÷ (√3 × Volts × PF)
Example: A 10 kW motor on 480V at PF 0.85 draws 10,000 ÷ (1.732 × 480 × 0.85) = 14.1 amps.
The calculator applies Watt's law for DC and resistive loads, then adds power factor for AC loads and the 1.732 multiplier for balanced three-phase line-to-line calculations.
DC and resistive loads: W = A x V
Single-phase AC: W = A x V x PF
Three-phase AC: W = 1.732 x A x V x PF
Editorial review
Last reviewed: June 7, 2026. This page is maintained by the Ampstowatt editorial team and checked for formula consistency, unit labels, calculator behavior, and safety wording.
The page is an educational planning reference, not a licensed electrical design or inspection service.
Every result shows the exact formula used — DC, AC single-phase, or AC three-phase — so you understand the calculation, not just the number. The working formula and all inputs are displayed alongside the result.
Real power factor support
Unlike basic calculators that ignore power factor, this tool lets you enter PF from 0.01 to 1.00 for motors, compressors, HVAC equipment, and other inductive loads. This gives you real power in watts instead of inflated apparent power.
Breaker and safety context
Results include a breaker planning reference with the NEC 80% continuous load rule. You get watts, kilowatts, and a practical safety check in one step — not just a bare number.
Voltage-specific sub-calculators
Dedicated pages for 12V, 120V, 220V, 230V, and 240V circuits with pre-set defaults and voltage-specific guidance — no need to re-enter voltage each time.
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Fast answers for the amps to watts formula, common conversions, and safe planning limits.
W How do I convert amps to watts?
Multiply amps by volts to get watts. For example, 10 amps at 120 volts equals 1,200 watts (10 × 120 = 1,200). For AC circuits with motors or compressors, also multiply by the power factor from the equipment nameplate.
AC What is the amps to watts formula?
There are three formulas depending on the circuit type. DC: Watts = Amps × Volts. AC single-phase: Watts = Amps × Volts × Power Factor. AC three-phase (line-to-line): Watts = 1.732 × Amps × Volts × Power Factor. The DC formula also works for pure resistive AC loads where power factor is 1.00.
1A How many watts is 1 amp?
1 amp equals a different number of watts depending on the voltage. At 12V, 1 amp = 12 watts. At 120V, 1 amp = 120 watts. At 240V, 1 amp = 240 watts. This assumes power factor of 1.00. For AC motor loads with lower power factor, the real watts will be lower.
VS What is the difference between amps and watts?
Amps (amperes) measure the flow rate of electric current — how much charge passes a point per second. Watts measure electric power — the rate at which electrical energy is used or converted to heat, light, or motion. You need both amps and volts to calculate watts: Watts = Amps × Volts.
SA Can I use amps to watts for breaker sizing?
You can use the result for load planning, but not for final breaker sizing. The NEC requires that continuous loads (3+ hours) stay at or below 80% of the breaker rating. A 20A breaker on 120V handles 2,400W maximum, but only 1,920W for continuous loads. Final sizing must account for wire gauge, ambient temperature, conduit fill, and local code.
PF Why does power factor matter in amps to watts conversion?
Power factor (PF) measures how efficiently a device uses current. Resistive loads like heaters use all the current for real work (PF = 1.0). Motors and compressors draw extra current due to inductance, so their power factor is lower (0.70–0.95). Without accounting for PF, you would overestimate watts by 10–40% for these loads.
⇄ How do I convert watts back to amps?
Divide watts by volts: Amps = Watts ÷ Volts. For AC with power factor: Amps = Watts ÷ (Volts × PF). For example, a 1,500W heater on 120V draws 1,500 ÷ 120 = 12.5 amps. This is useful for checking if an appliance will trip a breaker.
V Is the amps to watts formula different for 120V and 240V?
The formula is the same (Watts = Amps × Volts × PF), but the voltage value changes. At 240V, the same amperage produces twice the wattage as 120V. This is why high-power appliances like dryers and EV chargers use 240V circuits — they get more power without increasing wire size.