What BPM means, and how it's used in music, workouts, practice and video

What BPM means and the basic math

BPM stands for beats per minute: how many beats fall in one minute. A beat is the unit you naturally follow when you tap your foot or nod along to a song.

A minute is 60 seconds, so the length of one beat in seconds is 60 divided by the BPM. Going the other way, if you know the time between beats, 60 divided by that time gives you the BPM.

• 60 BPM: 1 second per beat (the speed of a clock's second hand)
• 90 BPM: about 0.67 seconds per beat
• 120 BPM: 0.5 seconds per beat (two per second)
• 150 BPM: 0.4 seconds per beat
• 180 BPM: about 0.33 seconds per beat (three per second)

The same abbreviation is used for heart rate (heartbeats per minute), which has nothing to do with musical BPM. If a fitness app's BPM is ambiguous, look for a heart or a music note next to the number.

Beats, bars and time signatures

Music groups beats into bars (measures). In the most common time signature, 4/4, there are four beats per bar, so a bar of a 120 BPM song lasts 0.5 × 4 = 2 seconds. In 3/4, the "oom-pah-pah" of a waltz, a bar has three beats, so at the same 120 BPM it lasts 1.5 seconds.

BPM counts beats, not bars, so it's calculated the same way whatever the time signature. In meters like 6/8, though, some people count each of the six small pulses as a beat and others count two beats per bar, so the same song can be listed with BPM values three times apart. When you read a BPM on sheet music or in track information, check which note value was counted as the beat.

Why one song can be 70 or 140

When people measure BPM, it's common for one person to say 70 and another 140 for the same song. Neither is wrong. Counting only the big kick drum hits gives 70; counting the snare or hi-hat in between gives 140. Musicians sometimes call these feels half-time and double-time.

Which one is right depends on what you need. To dance or work out, use the speed you actually want to move at; for a DJ mix, use whatever you'll match against other tracks; for sheet music, follow what the composer wrote. That's why the BPM Detector has ×0.5 and ×2 buttons: an automatic analysis can't know which beat you mean, so you choose based on how you'll use it.

In listening and DJ mixing

When a DJ blends two songs, matching their BPM is the starting point, because even a small tempo difference makes the beats drift apart over time. Do the math: start a 120 BPM track and a 121 BPM track together, and after one minute one is exactly a beat ahead; after just 30 seconds they're half a beat apart and the kicks sound off-beat.

Noting each song's BPM when building a playlist makes it easy to group similar tempos or order songs so they gradually speed up. If a file has no BPM information, analyze its opening with the BPM Detector or tap it out with the BPM Tapper.

In workouts and running

In running, the number of times your feet touch the ground per minute is called cadence (steps per minute). Step once per beat and your cadence equals the song's BPM; step once every two beats and your cadence is half the BPM. If you have a target cadence, pick songs at that BPM or at half of it.

For example, to take 160 steps a minute, match one step per beat in a 160 BPM song, or two steps per beat in an 80 BPM song. On an indoor bike, the same idea applies to pedal revolutions per minute.

In instrument practice

In practice, BPM is the metronome setting. A common approach is to set difficult passages below the target tempo, practice until they're clean, and then raise the tempo gradually.

You can work out the spacing of smaller note values from the BPM as well. At 120 BPM with a quarter note as the beat (0.5 seconds), eighth notes are 0.25 seconds apart and sixteenths 0.125 seconds. When a fast passage won't come together, thinking in "notes per second" shows how demanding the tempo is: sixteenths at 120 BPM are eight notes a second.

To internalize a tempo without a metronome, try the custom challenge in the BPM Tapper. Listen to four count-in beats and then hold the tempo silently for 15 seconds; the numbers show whether you tend to rush or to waver.

In video editing

When cutting video to music, it helps to know how many frames one beat lasts: multiply the frame rate (fps) by the beat length in seconds.

• 120 BPM at 30 fps: 0.5 s × 30 = 15 frames per beat
• 120 BPM at 24 fps: 0.5 s × 24 = 12 frames per beat
• 100 BPM at 30 fps: 0.6 s × 30 = 18 frames per beat
• 128 BPM at 30 fps: about 0.469 s × 30 = about 14.06 frames per beat (not a whole number)

As the last example shows, many tempos don't divide evenly into frames. Cutting at a fixed frame interval then makes cuts slide gradually off the beat as the song goes on. It's more accurate to watch the waveform in your editor and re-align a cut to the beat every few bars. The beat lines the BPM Detector draws over the waveform can help you find where the first beat lands.

Working out song and section lengths from BPM

With the BPM and time signature you can calculate how long a number of bars lasts: bars × beats per bar × (60 ÷ BPM). Sixty-four bars of a 120 BPM song in 4/4 is 64 × 4 × 0.5 = 128 seconds, or 2 minutes 8 seconds.

This is handy when fitting background music to a video or presentation. If a 30-second video uses a 120 BPM song in 4/4, 30 seconds is exactly 15 bars, so in a song built from 8-bar phrases you know ahead of time it will end halfway through the second phrase. If that sounds awkward, you can adjust the video to 32 seconds (16 bars).

A few related terms are worth knowing. The first beat of a bar is the downbeat, the space between beats is the off-beat, and the beats counted aloud before playing to set the tempo are the count-in. The four beats that play before a challenge in the BPM Tapper are a count-in.

Two ways to measure BPM

You can tap it yourself, or let software analyze the audio. Each is good at different things.

• Tapping: tap once per beat while listening and average the gaps. Because a person chooses which beat to count, there's no half-time/double-time confusion, and it works for live music or streamed songs with no file. On the other hand, human hands wobble, so don't expect decimal-place precision.
• Audio analysis: calculates how often the moments where the sound gets louder repeat in a file. On songs with a clear beat it gives a steady value to a decimal place, but it doesn't know which beat you mean, so it can return half or double, and it's unreliable when the beat is vague.

The surest approach is to use both. If the analysis is close to your tapped value, trust it; if it's exactly half or double, choose whichever suits your purpose.

Try it: checking one song's BPM

1. Play the song and, on the Free tap screen of the BPM Tapper, tap the pad or spacebar once per beat as if tapping your foot. After about 20 taps, write down the "Overall average".
2. If you have the song as a file, load it into the BPM Detector.
3. Compare the two. If they're within a few BPM, use the analyzed value; if it's exactly half or double, correct it with ×0.5 or ×2.
4. Use "Play with click track" for a final check by ear that the clicks line up with the drums.

Music that BPM doesn't describe well

• Changing tempos: in classical music or ballads where performers stretch and push the tempo expressively, a single BPM doesn't fit. Measure sections separately.
• Swing: when the subdivisions are uneven (long-short), you can still measure the beat's BPM, but the smaller note spacings won't match the straight calculation.
• Very slow songs: analysis tools usually search only within a set range. The BPM Detector looks between 60 and 200 BPM, so a slow song at 50 BPM tends to come out near double, around 100. Correct it with ×0.5.
• Beatless music: ambient or sound-design tracks have no repeating beat, so any number you assign means little.

Finally, a higher BPM doesn't automatically mean a livelier song. A 140 BPM track with a half-time feel can sound laid-back, and an 80 BPM track packed with fast subdivisions can sound busy. Remember that BPM tells you only the spacing of the beats, not the mood, and a lot of the confusion goes away.