BTU (th) to Millijoule Converter

Energy Converter

27 units available

Decimals:

From

To

1,054,350

1 BTU = 1,054,350 mJ

Formula:

mJ = BTU × 1,054,350

With your value: 1 BTU = 1,054,350 mJ

How big is that?

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

Heartbeat (1/1.1e+3 your value)0.000948 BTU

Your value1.00 BTU

AA battery charge (9.5× your value)9.48 BTU

Slice of bread (2.7e+2× your value)266 BTU

Daily food intake (8.0e+3× your value)7.97e+3 BTU

Litre of petrol (3.2e+4× your value)3.24e+4 BTU

Other BTU (th) to Millijoule conversions

2 BTU to mJ 3 BTU to mJ 4 BTU to mJ 5 BTU to mJ 6 BTU to mJ 7 BTU to mJ 8 BTU to mJ

BTU (th) to Millijoule Conversion Table

BTU (th) (BTU)	Millijoule (mJ)
0.5	527,175
1	1,054,350
2	2,108,700
5	5,271,750
10	10,543,500
15	15,815,250
20	21,087,000
25	26,358,750
50	52,717,500
100	105,435,000
250	263,587,500
500	527,175,000
1000	1,054,350,000

Millijoule to BTU (th) Conversion Table

Millijoule (mJ)	BTU (th) (BTU)
0.5	4.742258e-7
1	9.484517e-7
2	1.896903e-6
5	4.742258e-6
10	9.484517e-6
15	1.422677e-5
20	1.896903e-5
25	2.371129e-5
50	4.742258e-5
100	9.484517e-5
250	0.000237
500	0.000474
1000	0.000948

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

Millijoule (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 Millijoule

To convert from BTU (th) (BTU) to Millijoule (mJ), multiply the value by 1,054,350.

Formula: mJ = BTU × 1,054,350

Reverse: BTU = mJ × 9.484517e-7

Step-by-Step Example

Start with your value in BTU (th). For example: 5 BTU
Multiply by the conversion factor: 5 x 1,054,350
The result is: 5,271,750 mJ

About BTU (th)

The btu (th) (BTU) is a unit of energy and work. One btu (th) equals 1054.35 joules. UnitConvertLab converts it against every other energy unit using this exact definition, so results are reproducible to full double precision rather than rounded lookup tables.

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

About Millijoule

The millijoule (mJ) is a unit of energy and work. One millijoule equals 0.001 joules. UnitConvertLab converts it against every other energy unit using this exact definition, so results are reproducible to full double precision rather than rounded lookup tables.

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

Frequently Asked Questions

How many Millijoule are in 1 BTU (th)?

There are exactly 1,054,350 Millijoule in 1 BTU (th). This means the conversion factor from BTU (th) to Millijoule is 1,054,350.

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

The formula to convert BTU (th) to Millijoule is: mJ = BTU × 1,054,350. For example, to convert 10 BTU (th) to Millijoule, you would multiply 10 by 1,054,350.

What is a BTU (th)?