Power and Heat Flow Conversion Calculator

Enter Calculation

Value to Convert

From: watt (W) kilowatt (kW) joule per second (J/s) joule per minute (J/min) joule per hour (J/h) BTU [IT] per second BTU [IT] per minute BTU [IT] per hour BTU [th] per second BTU [th] per minute BTU [th] per hour calorie [IT] per second calorie [IT] per minute calorie [IT] per hour calorie [th] per second calorie [th] per minute calorie [th] per hour erg per second erg per minute erg per hour foot-pound-force per second foot-pound-force per minute foot-pound-force per hour foot-poundal per second foot-poundal per minute foot-poundal per hour cheval-vapeur (cv) pferdestarke (PS) horsepower (metric) horsepower (mechanical) horsepower (electric) horsepower (boiler) horsepower (water)

To: watt (W) kilowatt (kW) joule per second (J/s) joule per minute (J/min) joule per hour (J/h) BTU [IT] per second BTU [IT] per minute BTU [IT] per hour BTU [th] per second BTU [th] per minute BTU [th] per hour calorie [IT] per second calorie [IT] per minute calorie [IT] per hour calorie [th] per second calorie [th] per minute calorie [th] per hour erg per second erg per minute erg per hour foot-pound-force per second foot-pound-force per minute foot-pound-force per hour foot-poundal per second foot-poundal per minute foot-poundal per hour cheval-vapeur (cv) pferdestarke (PS) horsepower (metric) horsepower (mechanical) horsepower (electric) horsepower (boiler) horsepower (water)

Formula

Show calculation steps (1)

1. Convert to target unit

   

   Divide the watt value by the to-unit factor to express it in the target unit.

Results

Result

0.7456998716

in target unit

Value in watts (SI base)	745.6998715823 W

What this calculator does

This tool converts a value of power or heat-flow rate from any one unit into any other. Power measures energy delivered per unit time, so the same quantity can be written in watts, kilowatts, horsepower, BTU per hour, calories per second, ergs per second, foot-pounds-force per second and many more. Heat-flow rate uses the same units because heat is energy in transit. The calculator handles all of these through a single common reference: the SI base unit, the watt (W = joule per second).

How to use it

Enter the number you want to convert in "Value to Convert", pick the unit it is currently in under "From:", and pick the unit you want under "To:". The result appears instantly, along with the equivalent value expressed in watts for reference. Negative and zero values are valid because all conversions are pure linear scalings with no offset.

The formula explained

Every unit has a fixed factor that converts it into watts. The conversion is two steps: first multiply your input by the from-unit factor to get watts, then divide by the to-unit factor to get the target unit. Combined, $$\text{result} = \text{inputValue} \times \dfrac{f_{\text{from}}}{f_{\text{to}}}.$$ Because the factors are exact positive constants, there is never a divide-by-zero issue.

Conversion works by scaling the input through a common watt-based factor.

Worked example

Convert 1 horsepower (mechanical) to kilowatts. The mechanical horsepower factor is 745.69987 W and the kilowatt factor is 1000 W. So $$\text{watts} = 1 \times 745.69987 = 745.69987 \text{ W},$$ and $$\text{result} = \frac{745.69987}{1000} = 0.7457 \text{ kW}.$$ This matches the familiar rule that one mechanical horsepower is about 0.7457 kW.

FAQ

Are the different horsepower units the same? No. Metric horsepower, cheval-vapeur and pferdestarke are identical at 735.49875 W, but mechanical horsepower is about 745.7 W, electric is 746 W, water is 746.043 W, and boiler horsepower is about 9809.5 W.

What is the difference between IT and th calories or BTU? "IT" is the International Table definition and "th" is the thermochemical definition. They are slightly different units (for example \(1\ \text{cal[IT]} = 4.1868\ \text{J}\) versus \(1\ \text{cal[th]} = 4.184\ \text{J}\)), so choose the one your source uses.

Why show the value in watts? The watt is the SI base for power, so showing it gives a neutral reference and makes it easy to chain conversions or sanity-check the result.