Ohm Calculator
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A 20-amp circuit at 120 volts supplies up to 2,400 watts, with a safe continuous limit of 1,920 watts — the standard for kitchens, bathrooms, garages, and other heavy-use areas.
20 Amps to Watts: Kitchens, Bathrooms, and Garages
At 120 V, a 20-amp circuit yields 20 × 120 = 2,400 watts at maximum, with a continuous-load limit of 80%, or 1,920 watts (20 × 120 × 0.8). That extra headroom over a 15-amp circuit is exactly why higher-demand rooms are wired this way.
A 20-amp circuit requires thicker 12 AWG wire, which safely carries the higher current. The National Electrical Code mandates 20-amp circuits for heavy-use residential areas — kitchen countertop receptacles, bathrooms, laundry rooms, and garages — where appliances routinely draw more than a general-purpose outlet can supply. For the underlying conversion at any amperage, see our Amps to Watts calculator.
What Requires a 20-Amp Circuit?
High-draw appliances and power tools quickly exceed a 15-amp circuit and belong on a 20-amp one:
- Microwaves and countertop convection ovens (1,000–1,500 W)
- Blenders, food processors, and high-power toasters (800–1,800 W)
- Table saws, miter saws, and routers (1,500–1,800 W at start-up)
- Dust collectors, air compressors, and shop vacuums
- Portable air conditioners, garage heaters, and pressure washers
Watch the start-up surge: motor-driven tools like table saws and dust collectors briefly draw far more than their running wattage when they spin up, so sizing to the 1,920 W continuous limit leaves the margin those surges need.
20-Amp Conversion Chart
The same 20 amps produces very different power depending on the supply voltage:
| Voltage | Watts |
|---|---|
| 12 V | 240 W |
| 120 V | 2,400 W |
| 240 V | 4,800 W |
Frequently Asked Questions
What is Ohm's Law? +
Ohm's Law states that the current through a conductor between two points is directly proportional to the voltage across the two points, expressed as V = I × R (Voltage = Current × Resistance). It's the foundation for calculating power, where Watts = Amps × Volts.
How do I convert watts to kilowatts? +
Divide the number of watts by 1,000. For example, 2,500 watts equals 2.5 kilowatts. Kilowatts are typically used to describe larger loads and to measure energy consumption on your utility bill.
How is my electricity bill calculated? +
Utilities charge per kilowatt-hour (kWh). Multiply an appliance's power in kilowatts by the hours it runs to get kWh consumed, then multiply by your electricity rate. The Energy Cost tab above does this automatically for daily, monthly, and yearly estimates.
What is a kilowatt-hour (kWh)? +
A kilowatt-hour is a unit of energy equal to running a 1,000-watt appliance for one hour. It is the standard unit used by energy providers to measure and bill electricity usage.