Power Unit Converter

Posted by Robbie Dickson on

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Power Unit Converter + Reference Table & Engineering Applications

If you’ve ever found one spec in horsepower and another in watts, you know the drill—nothing lines up until you convert. This tool does those conversions for you. Just type in a value, pick its units, and you’ll see seven common power units side by side. You also get the formulas, conversion table, practical engineering notes, and some worked examples all on one page.

What Is Power Unit Conversion?

Converting power units just means expressing the same energy rate—how quickly work gets done or energy moves—in different units. Watts, horsepower, kilowatts, BTU/hr: these all measure power, just in different ways depending on industry or country.

Simple Explanation

Power is simply how quickly something uses or outputs energy. It’s like measuring the flow in a pipe: higher power means more energy per second. There are several units for this, but the underlying concept doesn’t change. A watt, a horsepower, and a BTU/hr all describe energy per time, just at different scales or for different trades.

Watts (W) kW ×1000 HP ×745.7 BTU/hr ÷0.29307 ft·lbf/min ÷0.0226 MW ×1,000,000 kcal/hr ÷1.163 Result = Value × (From_factor / To_factor)

Power Unit Converter

100 W
0.1 kW
0.0001 MW
0.1341 HP
341.21 BTU/hr
4424.78 ft·lbf/min
85.986 kcal/hr
Engineering calculation notice

This calculator is intended for education, concept evaluation, and preliminary design. Results are based on the equations and assumptions described on this page, but cannot account for every real-world load case, tolerance, material property, environmental condition, installation detail, safety factor, code, or regulatory requirement. Verify all inputs, assumptions, units, and results independently before selecting components or using the result in a real application. Safety-critical, structural, medical, lifting, transportation, or regulated applications must be reviewed by a qualified engineer.

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🎥 Video — Power Unit Converter

Power Unit Converter

How to Use This Calculator

No extra steps—just enter a value, pick a unit, and watch the answers show up automatically.

  1. Type your power value into the input. You can use any number, not just the default 100.
  2. Select your starting unit—watts, kilowatts, megawatts, horsepower, BTU/hr, ft·lbf/min, or kcal/hr.
  3. See all seven converted values right away, no need for a “calculate” button.
  4. Switch the source unit to see everything starting from a different base.
  5. Refer to the results for matching datasheets, sizing supplies, or checking energy and heat loads.

Power Unit Formula

All conversions go through watts as the common ground. Here’s the approach:

Value in Watts = Input Value × From_Factor
Result = Value in Watts ÷ To_Factor

The conversion factor for each unit just tells you “1 unit = how many watts.”

Symbol Unit Factor (Watts per 1 unit)
W Watt 1
kW Kilowatt 1,000
MW Megawatt 1,000,000
HP Horsepower (mechanical) 745.7
BTU/hr British Thermal Unit per hour 0.29307
ft·lbf/min Foot-pound-force per minute 0.0226
kcal/hr Kilocalorie per hour 1.163

Simple Example

Problem: You have a 100 W linear actuator and need to know its horsepower rating for a North American motor spec sheet.

Step 1 — Convert to base unit (watts):
The input is already in watts, so: 100 W × 1 = 100 W

Step 2 — Convert watts to horsepower:
100 W ÷ 745.7 = 0.1341 HP

Result: 100 W equals approximately 0.134 HP — roughly 1/8 of a horsepower. That's a typical draw for a FIRGELLI actuator under moderate load. Your standard 15A household circuit at 120V delivers about 1,800 W (2.4 HP), so this actuator uses a tiny fraction of available power.

Engineering Applications

The HP ≠ 750 W Myth

People like to round 1 HP to 750 W for mental math. The exact value is 745.7 W. That 0.6% may look small, but if you’re sizing 10 HP worth of equipment, that rounding is an extra 43 W unaccounted for. It might not matter in a classroom, but on a plant floor with real cables and circuit limits, you want the right number: 745.7 W.

Actuator Power in Context

Most linear actuators sit in the 20 to 100 W range under normal load—well below 1/4 HP. That means a basic DC supply can run one just fine. A 100 W actuator on 12V pulls about 8.3 amps; on 24V, half that. With multiple actuators, add up the wattages, size your supply, and call it a day.

BTU/hr and Thermal Management

BTU/hr matters when you’re trying to keep heat under control, often in enclosures or HVAC systems. If an actuator runs at 60 W and only 50% efficient, half that power—30 W—ends up as heat inside the box, which is 102 BTU/hr. In a sealed enclosure, heat like this accumulates quickly. Converting to BTU/hr lets you check if the built-in cooling or passive dissipation will keep up.

Regional Nameplate Differences

Motors in North America usually show HP; anywhere else, it’s kW. The motor itself doesn’t care, but you need to do the conversion if you’re swapping or comparing across countries. 1 HP equals about 0.75 kW (precisely, 0.7457 kW). So if you see a European motor rated at 0.75 kW, that’ll cover what would be called a “1 HP” motor in Canada or the US. Use the converter to skip the guessing.

Advanced Example

Scenario: You're designing a solar-powered gate system using a FIRGELLI actuator rated at 65 W. Your solar panel supplier specs everything in BTU/hr for their thermal analysis, your battery controller uses kW, and the gate contractor wants the horsepower rating. You need all 3 conversions.

Step 1 — Start with 65 W (already in base unit):
65 W × 1 = 65 W

Step 2 — Convert to kilowatts:
65 W ÷ 1,000 = 0.065 kW

Step 3 — Convert to horsepower:
65 W ÷ 745.7 = 0.08716 HP - roughly 1/11 of a horsepower.

Step 4 — Convert to BTU/hr:
65 W ÷ 0.29307 = 221.8 BTU/hr

Step 5 — Thermal check:
If the actuator motor runs at 60% efficiency, it dissipates 40% of 65 W as heat — that's 26 W, or about 88.7 BTU/hr. If your gate controller enclosure has a passive dissipation rating of 100 BTU/hr, you're within margin. If you also have a relay or driver board adding another 15 W of heat (51.2 BTU/hr), your total thermal load hits 139.9 BTU/hr — now you need ventilation or a larger enclosure.

Design interpretation: The actuator's 0.065 kW draw means a modest 100 W solar panel with a battery buffer handles this load easily, even with duty cycle factored in. The HP value (under 1/10 HP) confirms this is a light-duty application that won't stress any standard motor controller.

Frequently Asked Questions

Is 1 HP exactly 746 W or 745.7 W? +

1 mechanical horsepower equals 745.69987 W, which we round to 745.7 W for engineering use. The "746 W" figure you see in many textbooks is a further rounding. For most practical work, 745.7 gives you the accuracy you need without the extra decimal places.

What type of horsepower does this converter use? +

This converter uses mechanical (imperial) horsepower at 745.7 W. Electrical horsepower (746 W), metric horsepower (735.5 W), and boiler horsepower (9,809.5 W) are different values entirely. If your application involves metric HP or boiler HP, you'll need to apply the appropriate factor manually.

Can I use this for AC motor power ratings? +

Yes — this converts the numerical power value between units, which works the same whether the source is AC or DC. Just remember that AC motor nameplates may show apparent power in VA (volt-amps), which isn't the same as real power in watts. Make sure you're starting with real power (watts) for accurate conversions.

Why does the converter show BTU/hr and not just BTU? +

A BTU by itself is a unit of energy, not power. Power requires a time component — energy per unit time. BTU/hr divides energy by hours, giving you a rate that's directly comparable to watts. This is the standard unit used in HVAC for heating and cooling capacity.

How do I convert power to current draw for an actuator? +

Divide the power in watts by the supply voltage. A 60 W actuator on a 12V supply draws 60 ÷ 12 = 5 amps. On 24V, that same 60 W draws only 2.5 amps. This converter gives you the watts — then you apply Ohm's law (P = V × I) to get current.

What's ft·lbf/min and when would I actually use it? +

Foot-pound-force per minute measures mechanical power in imperial units — how much torque-driven work gets done per minute. You'll encounter it in legacy machinery specs, rotating equipment calculations, and some US industrial applications. Horsepower was originally defined as 33,000 ft·lbf/min, so the two units are closely related historically.

Does this converter account for motor efficiency? +

No — this is a pure unit conversion tool. It converts the number you input from one power unit to another. Motor efficiency, power factor, and mechanical losses are separate calculations you'd apply before or after the conversion. If a motor nameplate says 1 HP output, the electrical input will be higher depending on efficiency.

About the Author

Robbie Dickson — Chief Engineer & Founder, FIRGELLI Automations

Robbie Dickson brings over two decades of engineering expertise to FIRGELLI Automations. With a distinguished career at Rolls-Royce, BMW, and Ford, he has deep expertise in mechanical systems, actuator technology, and precision engineering.

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