Watt (W)
power
What does this unit measure?
power
Concrete reference
A 10 W lamp transfers 10 joules per second.
A useful way to begin
A concrete example
Why this matters
Understand the conversion
Method
The two units describe the same physical quantity. Use the conversion relation shown above, keep the units visible during the calculation, then check that the size of the result is plausible.
1 W = 1 J/s
Worked example
Starting with 1, apply 1 W = 1 J/s. The result is —. Writing the unit at each step helps prevent a correct number from being paired with the wrong unit.
Quick check
Before accepting a result, compare the relative size of the units. Converting to a larger unit usually gives a smaller numerical value; converting to a smaller unit usually gives a larger numerical value.
Precision
The calculator keeps more digits than are usually needed for everyday work. Round only at the end, and keep enough significant digits for the precision of the original measurement.