Btu to Joule Converter

Enter the value that you want to convert Btu (Btu) to joule (J) or joule to Btu.Also written as BTU to J conversion.

1 Btu = 1055.0558526 joule

Formula: joule = Btu value × 1055.0558526

BTU to J — Btu to joule

Value

Btu

Result

10550.55853J

10 Btu = 10550.55853 joule

Popular Energy Converters:

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Btu vs Joule

About the Btu

Btu (Btu) is a unit of energy measurement. 1 Btu is equal to 1055.0558526 joule.

The Joule in Engineering

Joule (J) is a unit of energy measurement. 1 joule is equal to 0.0009478 Btu.

Energy Units in Different Fields

Energy measurement units reflect their historical origins across different industries. Electrical engineers use kilowatt-hours, nutritionists use calories, physicists use joules, heating engineers use BTUs, and the petroleum industry uses barrels of oil equivalent. Converting between these units is essential for energy auditing, comparing fuel sources, sizing HVAC systems, and understanding electricity bills relative to gas consumption.

Btu to joule metric conversion table

0.01 Btu	=	10.55056 J
0.1 Btu	=	105.50559 J
1 Btu	=	1055.05585 J
2 Btu	=	2110.11171 J
3 Btu	=	3165.16756 J
4 Btu	=	4220.22341 J
5 Btu	=	5275.27926 J
6 Btu	=	6330.33512 J
7 Btu	=	7385.39097 J
8 Btu	=	8440.44682 J
9 Btu	=	9495.50267 J
10 Btu	=	10550.55853 J
11 Btu	=	11605.61438 J
12 Btu	=	12660.67023 J
13 Btu	=	13715.72608 J
14 Btu	=	14770.78194 J
15 Btu	=	15825.83779 J
16 Btu	=	16880.89364 J
17 Btu	=	17935.94949 J
18 Btu	=	18991.00535 J

19 Btu	=	20046.06120 J
20 Btu	=	21101.11705 J
30 Btu	=	31651.67558 J
40 Btu	=	42202.23410 J
50 Btu	=	52752.79263 J
60 Btu	=	63303.35116 J
70 Btu	=	73853.90968 J
80 Btu	=	84404.46821 J
90 Btu	=	94955.02674 J
100 Btu	=	105505.58526 J
200 Btu	=	211011.17052 J
300 Btu	=	316516.75579 J
400 Btu	=	422022.34105 J
500 Btu	=	527527.92631 J
600 Btu	=	633033.51157 J
700 Btu	=	738539.09683 J
800 Btu	=	844044.68210 J
900 Btu	=	949550.26736 J
1000 Btu	=	1055055.85262 J

How to Convert BTU to J (Btu to Joule)?

We can convert Btu to joule by using an example.

Example:

Convert 20 Btu to Joule?

We know 1 Btu = 1055.0558526 joule; 1 Joule = 0.0009478 Btu.

20 Btu = ___J

20 × 1055.0558526 = 21101.11705 J (we know 1 Btu = 1055.0558526 joule)

Answer:

20 Btu = 21101.11705 joule

How to Convert BTU to Joules (Step-by-Step)

The British Thermal Unit (BTU) is widely used in the HVAC industry, while the joule is the SI standard. The exact conversion is 1 BTU = 1055.06 J (International Table BTU). This conversion bridges US heating/cooling specifications with international engineering standards.

Identify the energy value in BTU from the equipment specification or energy audit.
Multiply the BTU value by 1055.06 to convert to joules.
For large values, consider expressing the result in kJ or MJ for readability.
Round to appropriate significant figures based on the original measurement precision.

💡 Tip: For quick estimation, multiply BTU by 1055 or roughly 1000 — this gives you joules within 5% accuracy, useful for back-of-envelope calculations in HVAC design.

Common BTU to Joules Conversions (HVAC & Heating)

Reference values for typical HVAC equipment ratings and heating energy measurements converted from BTU to joules.

Btu	Joule	Note
1 BTU	1,055.06 J	Base conversion factor
10 BTU	10,550.6 J	Small pilot light per minute
100 BTU	105,506 J	Match burning completely
1,000 BTU	1,055,060 J (≈1.055 MJ)	Hair dryer for ~1 minute
10,000 BTU	10.55 MJ	Small window AC unit rating
60,000 BTU	63.3 MJ	Mid-size residential furnace (per hour)
100,000 BTU	105.5 MJ	Therm of natural gas

Solved Examples: BTU to Joules

Question 1: A gas furnace is rated at 80,000 BTU/hr. How many joules per hour does it produce?

Solution:

Start with 80,000 BTU.

Multiply by 1055.06: 80,000 × 1055.06 = 84,404,800 J.

Convert to MJ: 84,404,800 ÷ 1,000,000 = 84.4 MJ.

Answer: 80,000 BTU = 84,404,800 J ≈ 84.4 MJ

Question 2: A water heater uses 4,500 BTU to raise the tank temperature. Express in joules.

Solution:

Start with 4,500 BTU.

Multiply by 1055.06: 4,500 × 1055.06 = 4,747,770 J.

Express in kJ: 4,747,770 ÷ 1000 = 4,747.8 kJ.

Answer: 4,500 BTU = 4,747,770 J ≈ 4,748 kJ

Question 3: An air conditioner removes 36,000 BTU/hr of heat. Convert to joules.

Solution:

Start with 36,000 BTU (a 3-ton AC unit).

Multiply by 1055.06: 36,000 × 1055.06 = 37,982,160 J.

This equals approximately 38.0 MJ per hour of cooling.

Answer: 36,000 BTU = 37,982,160 J ≈ 38.0 MJ

Practice: BTU to Joules

Try solving these on your own to test your understanding:

Convert 500 BTU to joules. (Answer: 527,530 J)
A space heater produces 5,000 BTU/hr. Express in joules. (Answer: 5,275,300 J)
Convert 12,000 BTU (1-ton AC) to megajoules. (Answer: ≈ 12.66 MJ)
A gas stove burner outputs 15,000 BTU/hr. How many kJ/hr is that? (Answer: ≈ 15,826 kJ)
Convert 250 BTU to joules. (Answer: 263,765 J)

Why HVAC Equipment Uses BTU Ratings

The BTU became the standard in American heating and cooling industries because it directly relates to practical measurements: 1 BTU is the energy needed to raise 1 pound of water by 1°F. This made it intuitive for boiler and furnace engineers in the 19th century. Today, all US furnaces, air conditioners, and water heaters are still rated in BTU/hr (or thousands of BTU/hr, written as MBH). International markets use watts or kilowatts for the same equipment specifications.

BTU Variants: IT vs Thermochemical

There are actually several BTU definitions. The International Table BTU (BTU_IT) equals exactly 1055.05585 J and is used in engineering. The thermochemical BTU equals 1054.35 J and appears in chemistry. The difference is less than 0.07%, so for HVAC work either value gives equivalent results. This converter uses the International Table definition as it is the most widely adopted standard.

Converting Furnace Ratings Between US and Metric

When shopping for heating equipment internationally, you need to convert between BTU/hr and watts (or kW). Since 1 BTU = 1055.06 J, and 1 watt = 1 J/s, then 1 BTU/hr = 1055.06/3600 ≈ 0.293 watts. So a 100,000 BTU/hr furnace is approximately 29.3 kW. Conversely, a 25 kW boiler common in Europe equals about 85,300 BTU/hr.

Key Takeaways

Multiply BTU by 1055.06 to get joules (International Table definition).
1 BTU is the heat to raise 1 pound of water by 1°F.
HVAC equipment in the US is rated in BTU/hr; international markets use watts.
For large values, convert to MJ: 1000 BTU ≈ 1.055 MJ.
A 12,000 BTU window AC unit (1 ton) = 12.66 MJ/hr ≈ 3.517 kW.
Quick estimate: BTU × 1000 gives joules within 5% accuracy.

Btu to Joule Conversion Formula

joule = Btu × 1055.0558526

1 Btu = 1055.0558526 joule

1 joule = 0.0009478 Btu

Reverse: Btu = joule × 0.0009478

Frequently Asked Questions

How many joule are in 1 Btu?

There are 1055.0558526 joule in 1 Btu. To convert Btu to joule, multiply the value by 1055.0558526.

How do I convert Btu to joule?

Multiply your Btu value by 1055.0558526 to get the equivalent in joule. For example, 5 Btu = 5 × 1055.0558526 = 5275.27926 joule.

How do I convert joule to Btu?

Multiply your joule value by 0.0009478 to get the equivalent in Btu. Alternatively, divide by 1055.0558526.

What is 10 Btu in joule?

10 Btu is equal to 10550.55853 joule.

What is 100 Btu in joule?

100 Btu is equal to 105505.58526 joule.