Power Unit Converter

Posted by Robbie Dickson on

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Power Unit Converter + Reference Table & Engineering Applications

You're speccing a motor, sizing a power supply, or checking whether your actuator setup will trip a breaker — and the datasheet gives you horsepower while your controller specs are in watts. This converter handles it instantly. Enter any power value, pick your units, and get live conversions across 7 common power units. This page also includes the reference formulas, a conversion table, worked examples, and practical engineering context for every unit.

What Is Power Unit Conversion?

Power unit conversion translates a single power measurement — the rate of doing work or transferring energy — between different unit systems like watts, horsepower, kilowatts, and BTU/hr.

Simple Explanation

Power is how fast energy gets used or produced. Think of it like water flow rate — a bigger pipe (more power) moves more water (energy) per second. Different industries and regions just measure that same "flow" using different units. A watt, a horsepower, and a BTU/hr all describe the same thing — just at different scales and in different traditions.

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

🎥 Video — Power Unit Converter

Power Unit Converter

How to Use This Calculator

This converter updates every result the moment you type or change a unit. No button needed — just follow these steps.

  1. Enter your power value in the input field. The default is 100, but type any number you need.
  2. Select your source unit from the dropdown — watts, kilowatts, megawatts, horsepower, BTU/hr, ft·lbf/min, or kcal/hr.
  3. Read all 7 converted values instantly in the result boxes below. Every unit updates in real time.
  4. Change the source unit to convert from a different starting point without re-entering the number.
  5. Use the results to match your motor datasheet to your controller specs, size a power supply, or verify thermal calculations.

Power Unit Formula

Every conversion flows through watts as the base unit. The formula is simple:

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

Where each unit's factor represents how many watts equal 1 of that unit:

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

You'll see 1 HP rounded to 750 W in a lot of quick-reference material. The actual value is 745.7 W. That 4.3 W difference sounds trivial — it's a 0.6% error — but it compounds. If you're sizing a 10 HP motor's electrical supply, the rounding error becomes 43 W. Scale that up to industrial multi-motor systems and you can end up undersizing cables, fuses, or VFDs by a meaningful margin. Always use 745.7 for engineering calculations. Save the 750 approximation for cocktail napkin estimates.

Actuator Power in Context

Most FIRGELLI actuators draw between 20 and 100 W under load — well under 1/4 HP. That's an important number to internalize because it means you can run most of our actuators off a modest 12V or 24V DC power supply without breaking a sweat. A 100 W actuator at 12V draws about 8.3 amps, which is well within the range of common automotive and robotics power supplies. If you're running multiple actuators simultaneously, just sum the wattages to size your supply correctly.

BTU/hr and Thermal Management

BTU/hr shows up everywhere in HVAC and thermal engineering. If you're putting an actuator inside an enclosure — a weatherproof control box, for example — you need to know how much heat that actuator's motor dumps into the space. An actuator drawing 60 W with 50% efficiency converts roughly 30 W into heat. That's about 102 BTU/hr. In a sealed enclosure with no ventilation, that heat builds up fast. This is exactly the scenario where converting watts to BTU/hr becomes a practical necessity rather than an academic exercise. You can then match that thermal load against your enclosure's passive dissipation rating or size an active cooling system.

Regional Nameplate Differences

Motor nameplates in North America typically show HP, while the same motor sold in Europe, Asia, or anywhere using the metric system shows kW. The motor hasn't changed — just the label. A 1 HP motor is a 0.7457 kW motor. This catches people when they're sourcing replacement motors internationally or comparing spec sheets from different suppliers. If a European datasheet says 0.75 kW, that's essentially 1 HP. Our converter eliminates the guesswork — punch in the number, pick the unit, and get an instant answer across all 7 systems.

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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