swap_horiz Looking to convert 15A at 100V back to watts?

How Many Amps Is 1,500 Watts at 100V?

1,500 watts at 100V draws 15 amps on an AC single-phase resistive circuit. Reactive or motor loads at the same real power draw more current than the resistive figure because of the power-factor penalty.

At 15A, the NEC 210.19(A) continuous-load sizing math (125% of the load, equivalently 80% of the breaker rating) points to a 20A breaker as the smallest standard size that covers this load continuously. A 15A breaker is the smallest standard size the raw current fits under, but it is non-continuous-only at this load.

1,500 watts at 100V

15 Amps

1,500 watts equals 15 amps at 100 volts (AC single-phase, PF 1.0 resistive)

DC15 A

Try: 1,400W at 100V 1,600W at 100V 1,300W at 100V 1,700W at 100V

Watts

Volts

Amps (AC 1Φ, PF 1.0)

Assumes an AC single-phase resistive load at PF 1.0. Typing a commercial L-L voltage (208/400/480V) re-routes the result to three-phase; 277V stays on single-phase because it's the L-N lighting leg of a 480Y/277V wye; 12/24V re-routes to DC.

Formulas

DC: Watts to Amps

I_(A) = P_(W) ÷ V_(V)

1,500 ÷ 100 = 15 A

AC Single Phase (PF = 0.85)

I_(A) = P_(W) ÷ (PF × V_(V))

1,500 ÷ (0.85 × 100) = 1,500 ÷ 85 = 17.65 A

Circuit Sizing

Breaker Sizing

NEC 240.6(A) standard ampere ratings for branch-circuit and feeder breakers start at 15, 20, 25, 30, 35, 40, 45, and 50A and continue at 60A and above for feeder and large-appliance circuits. At 15A, the smallest standard breaker the raw current fits under is 15A, but that breaker only covers 15A non-continuously; NEC 210.19(A) requires conductor and OCP sized at 125% of any continuous load (equivalently 80% of breaker rating), so for a continuous load the smallest compliant breaker is 20A. Final selection still depends on the equipment nameplate, whether the load is continuous, conductor ampacity, and local code.

Breaker Size	Max Continuous Load (80%)	Status for 15A
15A	12A	Non-continuous only
20A	16A	OK for continuous
25A	20A	OK for continuous
30A	24A	OK for continuous
35A	28A	OK for continuous
40A	32A	OK for continuous
45A	36A	OK for continuous
50A	40A	OK for continuous

Energy Cost

Running 1,500W costs approximately $0.26 per hour at the US average rate of $0.17/kWh (rates last reviewed April 2026). That is $2.04 for 8 hours or about $61.20 per month. See detailed cost breakdown.

AC Conversion Detail

The DC baseline for 1,500W at 100V is 15A. On an AC circuit with a power factor of 0.85, the current rises to 17.65A because reactive current flows alongside the real-power current.

Circuit Type	Formula	Result
DC	1,500 ÷ 100	15 A
AC Single Phase (PF 0.85)	1,500 ÷ (100 × 0.85)	17.65 A

Power Factor Reference

Power factor is the main reason 1,500W draws more current on AC than DC. At PF 1.0 (pure resistive, like a heater), the load pulls 15A at 100V on the single-phase basis the rest of the page uses. At PF 0.80 (typical induction motor), the same 1,500W pulls 18.75A. That is an extra 3.75A just to overcome the reactive component. Use the typical values below as a starting point, not for precise engineering calculations.

Load Type	Typical PF	1,500W at 100V (single-phase)
Resistive (heaters, incandescent)	1	15 A
Fluorescent lamps	0.95	15.79 A
LED lighting	0.9	16.67 A
Synchronous motors	0.9	16.67 A
Typical mixed loads	0.85	17.65 A
Induction motors (full load)	0.8	18.75 A
Computers (without PFC)	0.65	23.08 A
Induction motors (no load)	0.35	42.86 A

Same Wattage, Other Voltages

bolt1,500W at 12V = 125ADC bolt1,500W at 24V = 62.5ADC bolt1,500W at 120V = 12.5A1Φ, PF 1.0 bolt1,500W at 208V = 4.9A3Φ per line, PF 0.85 bolt1,500W at 220V = 6.82A1Φ, PF 1.0 bolt1,500W at 230V = 6.52A1Φ, PF 1.0 bolt1,500W at 240V = 6.25A1Φ, PF 1.0 bolt1,500W at 277V = 5.42A1Φ, PF 1.0 bolt1,500W at 400V = 2.55A3Φ per line, PF 0.85 bolt1,500W at 460V = 2.21A3Φ per line, PF 0.85 bolt1,500W at 480V = 2.12A3Φ per line, PF 0.85 bolt1,500W at 575V = 1.77A3Φ per line, PF 0.85

swap_horiz 15A to watts at 100V payments 1,500W running cost cable Wire size for 15A at 100V electrical_services 1.5 kW to amps science Ohm's law: 100V & 15A functions Watts to amps formula

Other Wattages at 100V

Watts	AC 1Φ Amps PF 1.0 resistive	AC 1Φ Amps PF 0.85 motor
500W	5A	5.88A
600W	6A	7.06A
700W	7A	8.24A
750W	7.5A	8.82A
800W	8A	9.41A
900W	9A	10.59A
1,000W	10A	11.76A
1,100W	11A	12.94A
1,200W	12A	14.12A
1,300W	13A	15.29A
1,400W	14A	16.47A
1,500W	15A	17.65A
1,600W	16A	18.82A
1,700W	17A	20A
1,800W	18A	21.18A
1,900W	19A	22.35A
2,000W	20A	23.53A
2,200W	22A	25.88A
2,400W	24A	28.24A
2,500W	25A	29.41A

Frequently Asked Questions

How many amps is 1,500W at 100V? expand_more

1,500W at 100V draws 15 amps on AC single-phase at PF 1.0 (resistive). For comparison at the same voltage: 15A on DC, 17.65A on AC single-phase at PF 0.85. Actual current depends on the load's power factor.

What is the 80% continuous load rule for 1,500W? expand_more

NEC 210.19(A) sizes the conductor and overcurrent device at not less than 125% of any continuous load (a load that runs three hours or more), equivalently 80% of the breaker rating. At 15A (the current the branch conductors actually carry on AC single-phase at PF 1.0 (resistive)), the minimum breaker that satisfies this is 20A under typical assumptions. Brief non-continuous use can run closer to the full breaker rating, but space heaters, EV chargers, and long-running appliances should be sized for the continuous case.

How much does 1,500W cost to run per hour? expand_more

At the US residential average of $0.17/kWh (last reviewed April 2026), 1,500W costs $0.26 per hour and $2.04 for 8 hours. Rates vary by utility and time of day.

Why does a 1,500W resistive heater draw fewer amps than a 1,500W motor at 100V? expand_more

Resistive loads like space heaters and toasters have a power factor of 1.0, so 1,500W at 100V on a single-phase AC basis draws 15A. An induction motor at the same wattage has a PF around 0.80, drawing 18.75A on the same basis. The extra current is reactive, it does no real work but still has to flow through the conductors and breaker.

Does voltage affect how many amps 1,500W draws? expand_more

Yes. Higher voltage means lower current for the same real power. 1,500W at 100V draws 15A on AC single-phase at PF 1.0 (resistive). As a resistive-baseline comparison at the same wattage, a DC or PF 1.0 load would draw 30A at 50V and 7.5A at 200V. Doubling the voltage halves the current and also halves the I²R losses in the conductors.

This calculator provides estimates for reference purposes only. Always consult a licensed electrician and verify compliance with the National Electrical Code (NEC) and local electrical codes before performing any electrical work.