How do you figure out what size heater you need?

Author: Miss Estel Walker  |  Last update: Thursday, February 19, 2026

For example, a 300 square foot room typically requires 7,000 BTUs to maintain a comfortable temperature, while a 1,000 square foot room requires 18,000 BTUs. A simple formula to determine your heating needs is: (desired temperature change) x (cubic feet of space) x . 133 = BTUs needed per hour.

How do I calculate what size heater I need?

The first technique is to simply figure the square footage of the space you want to heat. In warmer climates, multiply this number by 10 - 15. In more moderate climates, multiply by 20 - 30.

How big of a room will a 1500 watt heater heat?

In other words, a 1,500-watt heater will be great for a 250-square-foot room with central heat. If that same room had no other source of heat, you'd need a 2,000-watt heater.

How many BTUs for a 1500 sq ft house?

1,500-square-foot home would take between 45,000 and 90,000 BTUs. 1,800-square-foot home would take between 55,000 and 110,000 BTUs. 2,100-square-foot home would take between 65,000 and 125,000 BTUs. 2,400-square-foot homes would take between 75,000 and 145,000 BTUs.

How many square feet will 12000 BTU heat and cool?

12,000 BTU – ~550 sq. ft to ~800 sq. ft.

What Size Furnace Do I Need??

Is 8000 BTU enough for a bedroom?

If your space is 300 square feet, you want to find a model capable of producing at least 6,000 BTUs. As a guide, consider 5,000-BTU models for rooms 150 square feet or smaller, 8,000 BTUs for medium-size rooms (340 square feet), and 12,000 to 14,000-BTU models for rooms with square footage from 550 to 800.

How much does it cost to run a 1500 W heater for 24 hours?

Answer. To calculate the cost of running a 1500-watt heater for 24 hours in the US, you need to know the electricity cost per kilowatt-hour (kWh). If the average cost is about 16 cents per kWh (as of early 2023), the heater uses 1.5 kW x 24 hours = 36 kWh. Therefore, the cost would be 36 kWh x 16 cents = 5,76.

What is the difference between a 1500W and a 2000W heater?

Only the speed of heating will be more with 2000 watt. As far as the quanitity of hot water is same, you will need same heat content, for which same energy will be needed. For ex to provide 6000 Wh of heating, 1500 will take 4 hours and 2000 will take 3 hours.

Is a 5200 BTU heater good?

5,200 is a good rating for the perfect balance of heating and efficiency. If you get a heater that has a number of BTUs that is lower than that, it will struggle to keep your home warm while costing you a lot more in your heating bill since it is working at its maximum capacity.

How to calculate how much Btu you need?

Generally, your temperature control system should have 20 BTU for every square foot of living space in the area you wish to heat or cool. For example, if your room or area is 400 square feet in size, then you should opt for a temperature control system with a capability of around 8,000 BTU.

How many square feet will a 20 000 BTU heater heat?

To determine the number of BTUs per square foot that you need to heat a room, simply multiply the square footage by 20 BTUs per square foot. For example, if a room has 1,000 square feet, you would require 20,000 BTUs to heat it.

What is the rule of thumb for sizing unit heaters?

The minimum BTU a unit heater would need to have to properly cover the space would be 25,000. Another rule of thumb you can use to calculate BTU that is even simpler is 20 BTU per 1 square foot. Use this in cases where getting measurements or determining insulation may be more difficult.

What is the difference between a 1000W and 1500W heater?

1000 watts should warm up large bathrooms, small living rooms, or a small room. 1500 watts will heat spaces up to about 150 square feet and can help you stay warm and toasty in a medium-sized room, office, kitchen, or modest-sized living room.

What is the best heater for a large room?

Based on our research, ceramic and fan heaters are the best type of units for large spaces. More user-friendly than their infrared and oil-filled counterparts, they also heat up quickly, making them more effective than other options.

What size room will a 1500 watt heater heat?

As a rule of thumb it will require about 10 watts for every square foot. So the 1500 watt will usually heat up to 150 square feet. Heating question - trying to understand what size heater to ... I am trying to understand in layman terms what this actually ...

Is it cheaper to run a space heater or central heat?

But in general, since central heating powered by natural gas is cheaper than heat from electricity, heating a large space will cost less with an HVAC system that runs on gas.

What is the cheapest space heater to run?

Halogen heaters are among the most cost-effective electric heater options, with a typical power output of 1200W. Their immediate warmth in close proximity saves energy by not needing to be left running for long stretches of time.

Does a 1500 watt heater use a lot of electricity?

On average, space heaters use 1,500 watts of electricity.

Using a space heater 8 hours per day will use about 84 kilowatt-hours of electricity per week. It costs an average of $51.65 to run a space heater for a month and $258.26 to run for a year.

What happens if BTU is too high?

An air conditioner with BTUs that exceed the recommended square footage in your home may also take on more wear and tear over time because it will initiate its on/off cycle more frequently. It could also create a subpar cooling experience because your AC's compressor may turn off much sooner than it should.

Is it better to have more BTU or less?

A Higher BTU Number Doesn't Always Indicate a Better Product

On the other hand, AC units with too few BTUs will need to run constantly to reach the target temperature, which may add strain to the system. Therefore, it is crucial to choose the appropriate BTU based on the size of the space.

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