Turn on the song you want to measure and when you're ready press, "Start" on a stopwatch.
Tap your finger on a hard surface in time with the music. Try to match your taps to the beat of the music. Count out the number of taps you make in 15 seconds. Press "Stop" on the stopwatch. Write down the number of beats you counted.
Play the song again and count the number of beats. Do this three or four times to avoid errors in your count. If the song has different tempos, such as a slower bridge, you may also wish to count the beats per minute in this part of the song.
Average your numbers together by adding them together and dividing by the number of times you counted the beat. Multiply your number by 4 to get a count for one minute of song time. The averaged number represents the tempo of a song.
Set a metronome to a speed that matches the rhythm of the song. This is done differently on different kinds of metronomes, so you may need to experiment. Count out the beats that the metronome makes in one minute and write down the number.
Tap out the beat of a song using a free online program. These programs allow users to tap out the beats of songs on their keyboards to determine their tempo.