Convert 18 BTU (th) (BTU) to Megajoule (MJ).

18 BTU (th) equals 0.018978 Megajoule. Multiply 18 by 0.00105435.

What is 18 BTU (th) in Megajoule?

18 BTU (th) equals 0.018978 Megajoule.

How many Megajoules are in 1 BTU (th)?

There are exactly 0.00105435 Megajoules in 1 BTU (th). This means the conversion factor from BTU (th) to Megajoule is 0.00105435.

What is the formula to convert BTU (th) to Megajoule?

The formula to convert BTU (th) to Megajoule is: MJ = BTU × 0.00105435. For example, to convert 10 BTU (th)s to Megajoules, you would multiply 10 by 0.00105435.

What are the common uses of BTU (th)?

The BTU (th) is commonly used in energy calculations, engineering and science, education.

What is 18 BTU (th) in Megajoule?

To convert 18 BTU (th)s to Megajoules, multiply by 0.00105435. Therefore, 18 BTU (th) (BTU) equals 0.018978 Megajoule (MJ).

18 BTU (th) = 0.018978 Megajoule

Worked example: converting BTU (th) to Megajoule

Step 1 — start with the formula. MJ = BTU × 0.00105435
Step 2 — substitute your figure. 18 BTU × 0.00105435
Step 3 — read the result. 18 BTU = 0.018978 MJ
Step 4 — check it in reverse. BTU = MJ × 948.451652677 returns 17.9997 BTU, which matches the figure you started with.

Energy Converter

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0.018978

18 BTU = 0.018978 MJ

Formula:

MJ = BTU × 0.00105435

With your value: 18 BTU = 0.0189783 MJ

How big is that?

Everyday references on a logarithmic scale, all expressed in btu (th) so you can sanity-check the result.

Heartbeat (1/1.9e+4 your value)0.000948 BTU

AA battery charge (1/1.9 your value)9.48 BTU

Your value18.0 BTU

Slice of bread (15× your value)266 BTU

Daily food intake (4.4e+2× your value)7.97e+3 BTU

Litre of petrol (1.8e+3× your value)3.24e+4 BTU

Other BTU (th) to Megajoule conversions

13 BTU to MJ 14 BTU to MJ 15 BTU to MJ 16 BTU to MJ 20 BTU to MJ 21 BTU to MJ 24 BTU to MJ Full BTU (th) to Megajoule converter

BTU (th) to Megajoule Conversion Table

BTU (th) (BTU)	Megajoule (MJ)
0.5	0.000527
1	0.001054
2	0.002109
5	0.005272
10	0.010544
15	0.015815
20	0.021087
25	0.026359
50	0.052717
100	0.105435
250	0.263588
500	0.527175
1000	1.05435

Megajoule to BTU (th) Conversion Table

Megajoule (MJ)	BTU (th) (BTU)
0.5	474.225826
1	948.451653
2	1,896.903305
5	4,742.258263
10	9,484.516527
15	14,226.77479
20	18,969.033054
25	23,711.291317
50	47,422.582634
100	94,845.165268
250	237,112.913169
500	474,225.826339
1000	948,451.652677

Where these values come from

Every factor on this page is traced to the document that defines it. See the full provenance dataset or our methodology.

BTU (th) (BTU)

Energy

Exact conversion

The International Table BTU is exactly 1055.055 852 62 J.

Thermochemical and 39 °F BTU definitions differ by up to 0.2 %.

Source: NIST Special Publication 811, Guide for the Use of the International System of Units

National Institute of Standards and Technology (US) · Reviewed 2026-07-01

Megajoule (MJ)

Energy

Exact conversion

Derived from the joule (1 J = 1 kg·m²/s²). Thermochemical and IT calories, BTU and kWh are exact defined multiples.

Source: NIST Special Publication 811, Guide for the Use of the International System of Units

National Institute of Standards and Technology (US) · Reviewed 2026-07-01

How to Convert BTU (th) to Megajoule

To convert from BTU (th) (BTU) to Megajoule (MJ), multiply the value by 0.00105435.

Formula: MJ = BTU × 0.00105435

Reverse: BTU = MJ × 948.451652677

Step-by-Step Example

Start with your value in BTU (th). For example: 5 BTU
Multiply by the conversion factor: 5 x 0.00105435
The result is: 0.005272 MJ

BTU (th) and Megajoule Relationship

This conversion bridges the US Customary / Imperial and Metric (SI) measurement systems, commonly required when translating scientific data, international engineering specifications, or trade standards. Since 1 BTU (th) represents a fraction of a Megajoule (1 Megajoule ≈ 948.4517 BTU (th)s), the Megajoule is the larger measurement interval. Understanding the relationship between BTU (th) and Megajoule is essential for accurate calculations in physics, engineering, commerce, and daily applications.

About BTU (th)

The BTU (th) (symbol: BTU) is a recognized unit in the US Customary / Imperial measurement framework, utilized within energy applications for precision and standardized data representation.

Common uses of BTU (th): energy calculations, engineering and science, education.

About Megajoule

The Megajoule (symbol: MJ) is a recognized unit in the Metric (SI) measurement framework, utilized within energy applications for precision and standardized data representation.

Common uses of Megajoule: energy calculations, engineering and science, education.

Frequently Asked Questions

What is 18 BTU (th) in Megajoule?: 18 BTU (th) equals 0.018978 Megajoule.
How many Megajoules are in 1 BTU (th)?: There are exactly 0.00105435 Megajoules in 1 BTU (th). This means the conversion factor from BTU (th) to Megajoule is 0.00105435.
What is the formula to convert BTU (th) to Megajoule?: The formula to convert BTU (th) to Megajoule is: MJ = BTU × 0.00105435. For example, to convert 10 BTU (th)s to Megajoules, you would multiply 10 by 0.00105435.
What is a BTU (th)?: The BTU (th) (symbol: BTU) is a recognized unit in the US Customary / Imperial measurement framework, utilized within energy applications for precision and standardized data representation.
What is a Megajoule?: The Megajoule (symbol: MJ) is a recognized unit in the Metric (SI) measurement framework, utilized within energy applications for precision and standardized data representation.
What are the common uses of BTU (th)?: The BTU (th) is commonly used in energy calculations, engineering and science, education.

18 BTU (th) to Megajoule

Quick answer