What Are The Common Power Conversions?
Power conversion refers to changing a value that represents power from one unit to another. Some common units used to measure power include watts, horsepower, BTUs per hour, joules, kilowatt-hours, and kilowatts. Being able to convert between different power units is important for many scientific and engineering applications.
For example, when sizing a motor for a piece of equipment, you may know the required power in horsepower but need to convert to watts to select the proper motor. Or when calculating the energy consumption of an appliance, you may need to convert kilowatt-hours to joules. The ability to seamlessly move between power units allows for more effective analysis and communication.
In this article, we will cover some of the most common power conversions including:
- Watts to horsepower
- Horsepower to watts
- Watts to BTUs per hour
- BTUs per hour to watts
- Joules to kilowatt-hours
- Kilowatt-hours to joules
- Kilowatts to horsepower
- Horsepower to kilowatts
Understanding these fundamental power conversions will provide a solid foundation for tackling more complex power-related calculations and analyses.
Watts to Horsepower
The watt and horsepower are both units used to measure power, but they are different units. Here’s an explanation of each unit and how to convert between them:
A watt (symbol: W) is a unit of power in the International System of Units (SI). It measures the rate of energy conversion or transfer. For example, a 100-watt light bulb converts 100 joules of electrical energy per second into light and heat.
A horsepower (symbol: hp) is a non-SI unit of power. One horsepower is defined as exactly 745.7 watts. It was originally used to compare the output of steam engines to the power of draft horses.
To convert watts to horsepower, use the following formula:
Horsepower = Watts / 745.7
For example, to convert a 100-watt light bulb into horsepower:
Horsepower = 100W / 745.7 = 0.134 horsepower
So a 100-watt light bulb is equivalent to 0.134 horsepower. The conversion factor of 745.7 allows us to switch easily between these two common power units.
Horsepower to Watts
Horsepower (hp) and watts (W) are both units used to measure power, but they are different units. Horsepower is an imperial unit, while watts are metric units. However, it is possible to convert between horsepower and watts using a simple formula.
Horsepower measures the rate at which work is done. One horsepower is defined as the power needed to lift 33,000 pounds by one foot in one minute. Watts measure the rate of energy conversion or transfer. A watt is defined as one joule of energy per second.
The formula to convert horsepower to watts is:
Watts = Horsepower x 745.7
Where 745.7 is the conversion factor between horsepower and watts.
For example, if a motor has 10 horsepower, the wattage would be:
Watts = 10 hp x 745.7 W/hp
Watts = 7,457 W
So 10 horsepower equals 7,457 watts. This formula can be used to convert any horsepower value to watts.
Watts to BTUs per Hour
Watts and BTUs per hour are both units used to measure power, but they are different units. Watts (symbol W) are part of the metric system, while BTUs per hour (BTU/h) are part of the imperial system. The conversion between them is important for power calculations.
The formula for converting between watts and BTUs per hour is:
1 Watt = 3.412141633 BTU/h
To convert watts to BTUs per hour, multiply the watts by 3.412141633. For example:
100 Watts x 3.412141633 = 341.2141633 BTU/h
So 100 Watts is equal to 341.2141633 BTU/h. As another example:
500 Watts x 3.412141633 = 1706.070817 BTU/h
Therefore, 500 Watts is equal to 1706.070817 BTU/h. This conversion allows power ratings in watts to be expressed in BTUs per hour as needed.
BTUs per Hour to Watts
British Thermal Units (BTUs) and watts are two common units used to measure power. Here’s what you need to know about converting between them:
Definition of BTUs:
BTUs are a traditional unit of heat energy. One BTU is the amount of energy needed to raise the temperature of one pound of water by one degree Fahrenheit.
Definition of Watts:
A watt is a metric unit measuring power, or the rate of energy conversion or transfer. A watt is defined as one joule of energy per second.
Formula for Converting BTUs/Hour to Watts:
1 BTU/Hour = 0.2931 Watts
To convert BTUs per hour to watts, multiply the BTUs/hour by 0.2931.
Example:
Convert 100 BTUs/hour to watts:
100 BTUs/hour x 0.2931 = 29.31 Watts
Example:
Convert 500 BTUs/hour to watts:
500 BTUs/hour x 0.2931 = 146.55 Watts
Joules to Kilowatt Hours
Joules and kilowatt hours are both units used to measure energy. The joule is the International System of Units (SI) unit for energy, while the kilowatt hour represents the amount of energy consumed if work is done at the rate of 1 kilowatt for 1 hour.
To convert between these two units, we can use the following formula:
Kilowatt hours = Joules / 3,600,000
Where 3,600,000 is the number of joules in 1 kilowatt hour. This conversion essentially determines how many kilowatt hours are equivalent to the number of joules provided.
Let’s look at an example calculation:
Convert 10,000,000 joules to kilowatt hours:
Kilowatt hours = 10,000,000 joules / 3,600,000
= 2.78 kilowatt hours
So 10,000,000 joules equals 2.78 kilowatt hours. This conversion can be useful when analyzing energy consumption data provided in different units.
Kilowatt Hours to Joules
The kilowatt hour (kWh) is a unit of energy commonly used for electricity billing. The joule (J) is the standard unit of energy in the International System of Units (SI). Converting between kilowatt hours and joules allows you to determine the total amount of energy in joules when the value is provided in kilowatt hours.
The kilowatt hour represents the amount of energy consumed by a power of one kilowatt for one hour. One kilowatt hour is equivalent to:
1 kWh = 1000 W x 1 h
= 1000 J/s x 3600 s
= 3,600,000 J
So the conversion between kilowatt hours (kWh) and joules (J) is:
1 kWh = 3,600,000 J
To convert kilowatt hours to joules, multiply the kilowatt hours value by 3,600,000:
Joules = kilowatt hours x 3,600,000
Examples:
- Convert 10 kWh to joules:
Joules = 10 kWh x 3,600,000 J/kWh
= 36,000,000 J - Convert 50 kWh to joules:
Joules = 50 kWh x 3,600,000 J/kWh
= 180,000,000 J
Kilowatts to Horsepower
The kilowatt (kW) and horsepower (hp) are both units used to measure power. Understanding how to convert between kilowatts and horsepower is useful for comparing power measurements.
The kilowatt is defined as 1,000 watts of power. A watt is a derived unit of power that measures the rate of energy conversion or transfer. The horsepower is defined as the power needed to lift 33,000 pounds weight one foot in one minute.
The formula for converting kilowatts to horsepower is:
Horsepower = Kilowatts x 1.341
To convert kilowatts to horsepower, multiply the number of kilowatts by 1.341. Let’s look at some examples:
Example 1: Convert 5 kW to horsepower
5 kW x 1.341 = 6.705 hp
Example 2: Convert 12.5 kW to horsepower
12.5 kW x 1.341 = 16.763 hp
So in summary, to convert kilowatts to horsepower, simply multiply the kilowatts value by 1.341. This conversion allows you to calculate the equivalent horsepower measurement for a given kilowatt rating.
Horsepower to Kilowatts
Horsepower (hp) and kilowatts (kW) are both units used to measure power, but they are different from each other.
Horsepower is a unit that was originally defined as the power needed to lift 33,000 pounds one foot in one minute using a lever. It was later redefined to be exactly 550 foot-pounds per second, or about 745.7 watts.
Kilowatts measure power similarly to horsepower, but are defined using units from the metric system. One kilowatt is equal to 1,000 watts.
To convert between horsepower and kilowatts, a simple formula can be used:
Kilowatts = Horsepower x 0.7457
Or
Horsepower = Kilowatts / 0.7457
Here are some examples of converting between the two units:
- Convert 10 horsepower to kilowatts:
10 hp x 0.7457 = 7.457 kW - Convert 350 horsepower to kilowatts:
350 hp x 0.7457 = 261.095 kW - Convert 12.5 kilowatts to horsepower:
12.5 kW / 0.7457 = 16.76 hp
So in summary, horsepower and kilowatts are both power units but kilowatts are based on the metric system. The conversion between them involves multiplying or dividing by 0.7457.
Conclusion
In this article, we covered some of the most common power conversions including watts to horsepower, horsepower to watts, watts to BTUs per hour, BTUs per hour to watts, joules to kilowatt hours, kilowatt hours to joules, kilowatts to horsepower, and horsepower to kilowatts.
Being able to convert between different units of power is important for both calculations and comparisons. For example, when sizing a motor for an application, you may know the required power in horsepower but need to convert to watts to properly select the motor. Or when comparing the energy consumption of different appliances, converting to consistent units like kilowatt hours makes it easier to compare their usage.
Having a solid understanding of these key power conversions allows engineers, technicians, and anyone who works with motors, engines, or other powered equipment to perform critical calculations and size equipment properly. It also enables clearer comparisons between power sources and energy consumption across different devices and applications.
