Convert 100 Milliwatt (mW) to BTU/Hour (BTU/h).

100 Milliwatt equals 0.341214 BTU/Hour. Multiply 100 by 0.0034121416.

100 Milliwatt = 0.341214 BTU/Hour

Worked example: converting Milliwatt to BTU/Hour

Step 1 — start with the formula. BTU/h = mW × 0.0034121416
Step 2 — substitute your figure. 100 mW × 0.0034121416
Step 3 — read the result. 100 mW = 0.341214 BTU/h
Step 4 — check it in reverse. mW = BTU/h × 293.0710701722 returns 100 mW, which matches the figure you started with.

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Decimals:

From

To

0.341214

100 mW = 0.341214 BTU/h

Formula:

BTU/h = mW × 0.0034121416

With your value: 100 mW = 0.34121416 BTU/h

How big is that?

Everyday references on a logarithmic scale, all expressed in milliwatt so you can sanity-check the result.

Your value100 mW

LED bulb (90× your value)9.00e+3 mW

Laptop (6.5e+2× your value)6.50e+4 mW

Microwave oven (1.0e+4× your value)1.00e+6 mW

Electric kettle (3.0e+4× your value)3.00e+6 mW

Family car engine (9.0e+5× your value)9.00e+7 mW

Other Milliwatt to BTU/Hour conversions

80 mW to BTU/h 85 mW to BTU/h 90 mW to BTU/h 96 mW to BTU/h 120 mW to BTU/h 150 mW to BTU/h 200 mW to BTU/h Full Milliwatt to BTU/Hour converter

Milliwatt to BTU/Hour Conversion Table

Milliwatt (mW)	BTU/Hour (BTU/h)
0.5	0.001706
1	0.003412
2	0.006824
5	0.017061
10	0.034121
15	0.051182
20	0.068243
25	0.085304
50	0.170607
100	0.341214
250	0.853035
500	1.706071
1000	3.412142

BTU/Hour to Milliwatt Conversion Table

BTU/Hour (BTU/h)	Milliwatt (mW)
0.5	146.535535
1	293.07107
2	586.14214
5	1,465.355351
10	2,930.710702
15	4,396.066053
20	5,861.421403
25	7,326.776754
50	14,653.553509
100	29,307.107017
250	73,267.767543
500	146,535.535086
1000	293,071.070172

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.

Milliwatt (mW)

Power

Exact conversion

Derived from the watt (1 W = 1 J/s).

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

BTU/Hour (BTU/h)

Power

Exact conversion

Derived from the watt (1 W = 1 J/s).

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 Milliwatt to BTU/Hour

To convert from Milliwatt (mW) to BTU/Hour (BTU/h), multiply the value by 0.0034121416.

Formula: BTU/h = mW × 0.0034121416

Reverse: mW = BTU/h × 293.0710701722

Step-by-Step Example

Start with your value in Milliwatt. For example: 5 mW
Multiply by the conversion factor: 5 x 0.0034121416
The result is: 0.017061 BTU/h

About Milliwatt

The milliwatt (mW) is a unit of power. One milliwatt equals 0.001 watts. UnitConvertLab converts it against every other power unit using this exact definition, so results are reproducible to full double precision rather than rounded lookup tables.

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

About BTU/Hour

The btu/hour (BTU/h) is a unit of power. One btu/hour equals 0.2930710702 watts. UnitConvertLab converts it against every other power unit using this exact definition, so results are reproducible to full double precision rather than rounded lookup tables.

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

Frequently Asked Questions

What is 100 Milliwatt in BTU/Hour?

100 Milliwatt equals 0.341214 BTU/Hour.

How many BTU/Hour are in 1 Milliwatt?

There are exactly 0.0034121416 BTU/Hour in 1 Milliwatt. This means the conversion factor from Milliwatt to BTU/Hour is 0.0034121416.

What is the formula to convert Milliwatt to BTU/Hour?

The formula to convert Milliwatt to BTU/Hour is: BTU/h = mW × 0.0034121416. For example, to convert 10 Milliwatt to BTU/Hour, you would multiply 10 by 0.0034121416.

What is a Milliwatt?