Convert 21 Horsepower (Boiler) (hp (S)) to Horsepower (Metric) (PS).

21 Horsepower (Boiler) equals 280.081373 Horsepower (Metric). Multiply 21 by 13.3372082549.

21 Horsepower (Boiler) = 280.081373 Horsepower (Metric)

Worked example: converting Horsepower (Boiler) to Horsepower (Metric)

Step 1 — start with the formula. PS = hp (S) × 13.3372082549
Step 2 — substitute your figure. 21 hp (S) × 13.3372082549
Step 3 — read the result. 21 hp (S) = 280.081373 PS
Step 4 — check it in reverse. hp (S) = PS × 0.0749782099 returns 21 hp (S), which matches the figure you started with.

Power Converter

22 units available

Decimals:

From

To

280.081373

21 hp (S) = 280.081373 PS

Formula:

PS = hp (S) × 13.3372082549

With your value: 21 hp (S) = 280.08137335 PS

How big is that?

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

LED bulb (1/2.3e+4 your value)0.000917 hp (S)

Laptop (1/3.2e+3 your value)0.00663 hp (S)

Microwave oven (1/2.1e+2 your value)0.102 hp (S)

Electric kettle (1/69 your value)0.306 hp (S)

Family car engine (1/2.3 your value)9.17 hp (S)

Your value21.0 hp (S)

Other Horsepower (Boiler) to Horsepower (Metric) conversions

15 hp (S) to PS 16 hp (S) to PS 18 hp (S) to PS 20 hp (S) to PS 24 hp (S) to PS 25 hp (S) to PS 26 hp (S) to PS Full Horsepower (Boiler) to Horsepower (Metric) converter

Horsepower (Boiler) to Horsepower (Metric) Conversion Table

Horsepower (Boiler) (hp (S))	Horsepower (Metric) (PS)
0.5	6.668604
1	13.337208
2	26.674417
5	66.686041
10	133.372083
15	200.058124
20	266.744165
25	333.430206
50	666.860413
100	1,333.720825
250	3,334.302064
500	6,668.604127
1000	13,337.208255

Horsepower (Metric) to Horsepower (Boiler) Conversion Table

Horsepower (Metric) (PS)	Horsepower (Boiler) (hp (S))
0.5	0.037489
1	0.074978
2	0.149956
5	0.374891
10	0.749782
15	1.124673
20	1.499564
25	1.874455
50	3.74891
100	7.497821
250	18.744552
500	37.489105
1000	74.97821

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.

Horsepower (Boiler) (hp (S))

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

Horsepower (Metric) (PS)

Power

Exact conversion

Metric horsepower (PS) is exactly 75 kgf·m/s = 735.498 75 W.

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 Horsepower (Boiler) to Horsepower (Metric)

To convert from Horsepower (Boiler) (hp (S)) to Horsepower (Metric) (PS), multiply the value by 13.3372082549.

Formula: PS = hp (S) × 13.3372082549

Reverse: hp (S) = PS × 0.0749782099

Step-by-Step Example

Start with your value in Horsepower (Boiler). For example: 5 hp (S)
Multiply by the conversion factor: 5 x 13.3372082549
The result is: 66.686041 PS

About Horsepower (Boiler)

The horsepower (boiler) (hp (S)) is a unit of power. One horsepower (boiler) equals 9809.5 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 Horsepower (Metric)

The horsepower (metric) (PS) is a unit of power. One horsepower (metric) equals 735.49875 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 21 Horsepower (Boiler) in Horsepower (Metric)?

21 Horsepower (Boiler) equals 280.081373 Horsepower (Metric).

How many Horsepower (Metric) are in 1 Horsepower (Boiler)?

There are exactly 13.3372082549 Horsepower (Metric) in 1 Horsepower (Boiler). This means the conversion factor from Horsepower (Boiler) to Horsepower (Metric) is 13.3372082549.

What is the formula to convert Horsepower (Boiler) to Horsepower (Metric)?

The formula to convert Horsepower (Boiler) to Horsepower (Metric) is: PS = hp (S) × 13.3372082549. For example, to convert 10 Horsepower (Boiler) to Horsepower (Metric), you would multiply 10 by 13.3372082549.

What is a Horsepower (Boiler)?