How many amps is 1500 watts at 120 volts?
1500 watts at 120 volts is 12.5 A — what a space heater, hair dryer or kettle draws on high from a household outlet.
How to work it out
- 1,500 W ÷ 120 V = 12.5 A
Fifteen hundred watts is the top setting of many plug-in heaters and hair dryers. On household power it is a routine 12.5 A; on a battery inverter it becomes one of the hardest loads you can ask a small system to carry.
Adjust for your project
- Energy per hour of running
- 1.5 kWh
| Voltage | Amps | Amps × volts |
|---|---|---|
| 12 V | 125 A | 1,500 W |
| 24 V | 62.5 A | 1,500 W |
| 48 V | 31.3 A | 1,500 W |
| 120 V | 12.5 A | 1,500 W |
| 240 V | 6.3 A | 1,500 W |
- A standard US 15 A household circuit is meant to carry less than its full rating for loads that run for hours. Check the circuit breaker and the appliance manual before adding a big load to an existing circuit.
Amps for common loads at the voltage above
| Power | Current |
|---|---|
| 100 | 0.8 A |
| 300 | 2.5 A |
| 500 | 4.2 A |
| 1000 | 8.3 A |
| 1500 | 12.5 A |
| 2000 | 16.7 A |
| 3000 | 25 A |
What to know about a 1500 W load
- One per circuit. A standard US 15 A circuit shares its capacity with everything else on it, and long-running loads should stay below the breaker’s rating. A 1500 W heater plus a microwave on the same circuit is a classic tripped breaker.
- On a generator, it is running watts. A heater has no start surge, so a generator only needs comfortably more than 1500 running watts — see the generator size calculator.
- On a 12 V battery it is about 139 A. 1500 W ÷ 12 V is 125 A before losses and about 139 A through a 90% inverter. That needs a 2000 W-class inverter and a battery bank rated for the current.
- 110, 115 or 120 V? They are names for the same household supply; the math changes by a few percent. At 110 V the figure is about 13.6 A.
What does that cost to run? The cost to run a space heater prices 1500 W by the hour. On a 12 V system the equivalent page is how many amps is 1000 watts at 12 volts.
Different size? Use the full Watts to Amps Calculator.
What you’ll need
- Plug-in electricity usage monitorBudget price
Plugs in between the wall and a 120 V appliance and shows real watts and kWh over a day — the honest way to fill in a load list, especially for fridges that cycle on and off.
See options on Amazon (opens in a new tab) - Pure sine wave inverter, 2000–3000 WPremium price
For microwaves, coffee makers and power tools. At 12 V these draw hundreds of amps, so the battery and cabling matter as much as the inverter.
See options on Amazon (opens in a new tab)
As an Amazon Associate we earn from qualifying purchases. Links to products are affiliate links — they cost you nothing extra and help keep these calculators free.
Frequently asked questions
How many amps is 1500 watts at 240 volts?
6.3 A.
How many amps is 1500 watts at 12 volts through an inverter?
125 A before losses, and about 138.9 A from the battery through a 90% inverter.
Other common sizes
- How many amps is 1000 watts at 12 volts — 83.3 A (92.6 A through an inverter)
- 400 watts to amps at 12V — 33.3 A
Sources
- Virginia Cooperative Extension, BSE-301: Estimating Appliance and Home Electronic Energy Use (2020) (opens in a new tab) — Wattage × hours ÷ 1,000 = kWh per day; watts = amps × volts when only amps are listed; a refrigerator runs at full wattage about a third of the time; typical nameplate wattages.
- Victron Energy — Energy Unlimited (book) (opens in a new tab) — Lead-acid charge efficiency 80–95% (85% suggested as a starting value); battery energy efficiency about 75% for full cycles, about 89% in partial state of charge; inverter efficiencies above 90%.
- Victron Energy — Which solar charge controller: PWM or MPPT? (2020) (opens in a new tab) — MPPT output current = panel watts ÷ battery voltage (100 W ÷ 13 V = 7.7 A); a PWM controller pulls the panel down to battery voltage (81 W from a 100 W panel at 25 °C, about the same as MPPT at 75 °C); temperature-coefficient method; example panel Voc 21.6 V, −0.35 %/°C.