People often plug standard heaters into crowded electrical circuits, which leads to tripped breakers and melted wires. You must treat these devices as major appliances because most space heaters draw 1,500 watts on their maximum setting and 750 to 900 watts on low. Small personal space heaters typically consume between 200 and 500 watts. Calculating your exact power needs prevents electrical hazards and keeps your winter energy bills under control.
Quick answer
Most space heaters consume 1,500 watts of electricity on their highest setting. You need roughly 10 watts of heating power for every square foot of room space. Plugging a 1,500-watt heater into a shared circuit often causes tripped breakers.
- Best for standard bedrooms: 1,500W heaters
- Best for office desks: 250W personal heaters
- Standard space heaters draw 12.5 amps, taking up 83% of a typical household circuit.
- You should size your heater using the 10-watt rule (e.g., 150 square feet requires 1,500 watts).
- Never plug a space heater into a power strip or extension cord due to severe fire risks.
- Zone heating with a single space heater costs roughly 26 cents per hour at the US national average electricity rate.
- How many watts does a space heater use?
- How many watts does a small space heater use?
- What wattage space heater do I need for my room size?
- Space heater 1300 watts vs 1500
- Can a space heater cause a power outage or trip a breaker?
- Why can’t I plug a space heater into a power strip?
- Space heater power usage vs central heat
- What do owners say?
- Frequently Asked Questions
How many watts does a space heater use?
Most standard space heaters use 1,500 watts on their maximum setting and 750 to 900 watts on their low setting. This power draw translates to 12.5 amps on a standard 120V US electrical outlet. That is a heavy load. It is the same amount of power used by a large microwave or a hair dryer.
Manufacturers design plug-in heaters to max out at 1,500 watts. US household wall outlets are typically wired to 15-amp breakers. 1,500 watts is the absolute legal and safe limit for a continuous heating device on these standard plugs. If you turn the device to its “low” or “eco” mode, the internal elements step down the power to around 750 watts. This cuts your electricity usage in half and reduces the strain on your home wiring.
How many watts does a small space heater use?
Small personal desk heaters draw significantly less power, usually between 200W and 500W. These compact units are designed for tight spaces. They heat a person, not an entire room.
Because they draw fewer watts, personal heaters are much safer for shared electrical circuits. If you work in an office building, plugging a 1,500W heater into your cubicle wall will likely trip the breaker for the whole row of desks. A 250W heater only pulls about 2 amps. This leaves plenty of capacity for computers, monitors, and chargers.
What wattage space heater do I need for my room size?
You need approximately 10 watts of heating power per square foot of interior space. This general industry rule of thumb helps you match the heater output to your room without wasting electricity.
If you buy a heater that is too small, it will run constantly without ever reaching your target temperature. If you buy one that is too large, you might overload your electrical circuit unnecessarily. Here is a quick-reference sizing chart based on the 10-watt rule:
| Room Size (Square Feet) | Recommended Wattage | Typical Room Type |
|---|---|---|
| 50 sq ft | 500 Watts | Bathroom or small cubicle |
| 100 sq ft | 1,000 Watts | Small bedroom or home office |
| 150 sq ft | 1,500 Watts | Standard primary bedroom |
| 200+ sq ft | Multiple Heaters Needed | Large living room or basement |
- If you need to heat just your legs at a desk: Buy a 200W to 500W personal heater.
- If you need to heat a closed 10×15 bedroom: Buy a standard 1,500W radiant or ceramic heater.
- If you need to heat an open-plan living room: Do not rely on plug-in space heaters alone; use your central heat.
Space heater 1300 watts vs 1500
The main difference between a 1300-watt and a 1500-watt space heater is the margin of safety they leave on your electrical circuit. A 1300W heater draws about 10.8 amps, while a 1500W heater draws 12.5 amps.
Both models will heat a standard bedroom. However, a typical US household circuit handles a maximum of 15 amps. When you run a 1500W heater, you only have 2.5 amps left for anything else plugged into that room. Running a 1300W heater leaves a slightly safer margin of 4.2 amps. This extra wiggle room can be the difference between a warm room and a sudden trip to the breaker box.
Can a space heater cause a power outage or trip a breaker?
Yes, a space heater can absolutely trip a breaker. A standard 15-amp household circuit maxes out at 1,800 watts (15 amps x 120 volts). A 1,500W heater consumes 83% of the circuit’s total capacity.
If you turn on any other moderate-draw appliance on the same circuit, the total load will exceed 1,800 watts. The breaker is doing its job by tripping to prevent the wires inside your walls from melting.
From the Shop
Based on what we see on the bench, the most common reason a heater “stops working” is actually a tripped breaker. Homeowners often plug a heater into the living room wall, unaware that the outlet shares a circuit with the hallway. As soon as someone turns on a 1,200-watt vacuum cleaner out in the hall, the system tries to pull 2,700 watts through a 1,800-watt wire. The breaker trips instantly.
Circuit Safety Checklist
Never run a 1,500W space heater on the same circuit simultaneously with these common devices:
- Hair dryers or curling irons (1,500W)
- Vacuum cleaners (1,000W – 1,400W)
- Microwaves (1,000W)
- High-end gaming PCs (600W – 800W)
- Window air conditioners (900W+)
Why can’t I plug a space heater into a power strip?
Plugging a 1500W heater into a standard power strip can cause melting or fire because standard strips are not rated to handle continuous 12.5-amp thermal loads. You must always plug a space heater directly into a wall receptacle.
Power strips and extension cords create extra electrical resistance at the connection points. When 12.5 amps of electricity forces its way through these cheap connections for hours at a time, the metal heats up drastically.
Space heater power usage vs central heat
Comparing space heaters to central heat comes down to “zone heating.” A central electric furnace might use 10,000 to 15,000 watts to heat your entire house. A single space heater uses 1,500 watts to heat one room. If you turn your central thermostat down and only heat the room you are sitting in, you save money.
Let us calculate the exact cost to run a standard heater. We will base this on US electricity prices from the U.S. Energy Information Administration in October 2026, where the national average is near 17 cents per kilowatt-hour (kWh).
The Math:
- A 1,500W heater equals 1.5 kilowatts (kW).
- Running it for 1 hour uses 1.5 kWh of energy.
- 1.5 kWh x $0.17 per kWh = $0.255.
It costs roughly 26 cents an hour to run a standard space heater on high. If you run it for 8 hours overnight, you will spend about $2.04 per day. This is highly cost-effective if it allows you to lower the central thermostat for the rest of a large house.
What do owners say?
Owners like
- Eco-modes that automatically step down wattage (e.g., from 1500W to 750W) when the room reaches the target temperature.
- Low-wattage personal heaters (200W-500W) are perfect for office cubicles because they don’t trip shared breakers.
- Digital wattage readouts on newer models help users manage their electricity use and avoid overloading circuits.
Common complaints
- Tripping the breaker whenever another appliance (like a vacuum or hair dryer) is turned on in another room sharing the same circuit.
- The plug or power cord gets noticeably warm or hot to the touch after running on the 1500W setting for over an hour.
- Frustration when manufacturers claim 1500W output but the fan is too weak to push the heat across the room.
- Power switches or plugs melting after continuous heavy winter use.
Summarised from owner reviews and long-term user reports; individual experiences vary.
Frequently Asked Questions
What wattage space heater do I need?
You need a heater that provides 10 watts for every square foot of floor space. For a standard 150-square-foot bedroom, you need a 1,500-watt model. For a small 50-square-foot bathroom or desk area, a 500-watt model is sufficient.
How many watts does a space heater use?
Most standard portable space heaters use 1,500 watts of electricity when set to their maximum heat setting. When switched to a low or eco setting, they typically consume between 750 and 900 watts.
How many watts does a small space heater use?
Small personal space heaters designed for office desks usually consume between 200 and 500 watts. This lower power draw makes them ideal for shared electrical circuits where a larger heater would trip the breaker.
Can space heater cause power outage?
While they rarely cause wide-scale neighborhood power outages, space heaters frequently cause localized power outages in homes by tripping the circuit breaker. This happens when the heater’s 12.5-amp load combines with other appliances to exceed the 15-amp limit of the household wiring.
How many watts does it take to run a space heater?
It takes 1,500 watts to run a full-size room heater on high, and about 750 watts to run it on low. Personal desk heaters take between 200 and 500 watts to run.
Why space heater power strip?
You should never plug a space heater into a power strip. Standard power strips are not built to handle the continuous 12.5-amp electrical load that a 1,500W heater demands. The sustained heat will melt the plastic components inside the power strip, posing a severe fire hazard.
Space heater 1300 watts vs 1500?
A 1500W space heater puts out more total heat but consumes 83% of a standard 15-amp electrical circuit. A 1300W model generates slightly less heat but is much less likely to trip your circuit breaker if you have other small devices plugged into the same room.
Space heater power usage vs central heat?
A central electric heating system uses 10,000 to 15,000 watts to heat a whole house, while a space heater uses only 1,500 watts to heat a single room. Using a space heater saves energy and money only if you turn down the central thermostat and practice zone heating.
