Electric Heater BTU Calc: How Many BTU Is 1500 Watt Heater?

How many BTU do space heaters produce? When you get a space heater, you will probably want to know how much heat it can generate (measured in BTU). Electric heaters, however, only have a specified wattage input. Example: 1500 watt space heater.

Here’s the deal:

  • Electric heaters have a power input (anywhere from 100W to 20,000W).
  • They produce heating output (anywhere from 341 BTU to 68,240 BTU).
How Many BTU Is 1500 Watt Heater calculated
Standard electric heater is powered by 1500 watts.

Almost 100% of electric power input (wattage) is converted to heating output (BTUs). In reality, about 98% of electricity is converted to heat but for all calculations let’s presume the efficiency is 100%.

If you want to convert watts to BTUs, you only need to know this conversion rule:

1 Watt = 3.412 BTU

Based on this rule, we can tell how many BTU does any electric heater produce.

Example: How many BTU is 1500 watt heater?

Simple. Just multiply 1500W by 3.412 BTU/W like this:

Heater BTUs (1500W) = 1500W × 3.412 BTU/W = 5118 BTU

In short, 1500 watt heater produces 5118 BTU of heating output. This is enough to heat up to 171 sq ft of living area.

To help you out with these calculations, we have prepared 3 useful resources you can freely use, namely:

  1. Electric Heater BTU Calculator. Here you can just insert the wattage of your heater and the calculator will automatically calculate the amount of heating output (BTUs) this heater generates.
  2. Electric Heater Wattage To BTU Chart + Coverage Area. We have converted 100W to 20,000W heaters to BTU. On top of that, we have also applied a 30 BTU per sq ft rule of thumb to calculate how many square feet can different wattage heaters heat.
  3. How many BTUs is 1500W heater? This is an example of how to convert standard 1500 heating watts to BTU and square footage.

Electric Heater Watts To BTU Calculator

Here you can just insert electric heater wattage and get the BTUs (heating output):


Now that you have BTU output, you will probably want to know what size area can such a heater producing this amount of heating output cover.

For this, we can use the simple 30 BTU per sq ft of living space rule and calculate the coverage area. We have calculated all of this (watts to BTU and BTU to sq ft) and gathered the results in the table below:

Electric Heater Wattage To BTU Chart + Coverage Area

Heater Wattage: BTUs: Coverage (30 BTU/Sq Ft):
100 Watts 341 BTU 11.4 Sq Ft
200 Watts 682 BTU 22.7 Sq Ft
300 Watts 1024 BTU 34.1 Sq Ft
400 Watts 1365 BTU 45.5 Sq Ft
500 Watts 1706 BTU 56.8 Sq Ft
600 Watts 2047 BTU 68.2 Sq Ft
700 Watts 2388 BTU 79.6 Sq Ft
800 Watts 2730 BTU 90.9 Sq Ft
900 Watts 3071 BTU 102 Sq Ft
1000 Watts 3412 BTU 114 Sq Ft
1250 Watts 4265 BTU 142 Sq Ft
1500 Watts 5118 BTU 171 Sq Ft
2000 Watts 6824 BTU 227 Sq Ft
3000 Watts 10,236 BTU 341 Sq Ft
4000 Watts 13,648 BTU 455 Sq Ft
5000 Watts 17,060 BTU 568 Sq Ft
10,000 Watts 34120 BTU 1140 Sq Ft
15,000 Watts 51,180 BTU 1710 Sq Ft
20,000 Watts 68,240 BTU 2270 Sq Ft

Using this chart, you can easily figure out how many BTU do different wattage heaters have.

Let’s have a look at the standard 1500 watt heater to illustrate how these calculations are made manually:

How Many BTU Is A 1500 Watt Heater?

1500W is the standard space heater capacity. More than 50% of all space heaters have an electric input of 1500W. Here is how we can calculate how many BTUs is 1500 watts as we have done in the intro:

Heater BTUs (1500W) = 1500W × 3.412 BTU/W = 5118 BTU

Now we can calculate how many sq ft can a 1500 watt heater adequately heat. For heating, we need about 30 BTU per sq ft. Here is how we can determine the square footage 1500 watt heater can cover:

Coverage Area (1500W) = 5118 BTU / 30 BTU Per Sq Ft = 171 Sq Ft

As you can see, a 1500 watt heater can heat up to 171 sq ft of living space.

Hopefully you now understand how to convert watts to BTUs for electric space heaters. If you need any help with the calculations, just use the comment section below and we’ll try to help you out.

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