Convert between beat interval (ms) and BPM. Includes derived note durations (half, eighth, sixteenth) — handy for setting echo and delay times by ear.
Inputs
≥ 1 ms
Time between two consecutive quarter-note beats, in milliseconds. Measure by tapping along to the music or reading off a delay pedal.
Results
Quarter-note beats per minute, computed as 60 000 ÷ beat interval.
Duration of a half note (two beats) — set delays to this for spacious eighth-bar echoes.
Duration of an eighth note (half a beat) — the most common tempo-synced delay setting.
Duration of a sixteenth note (a quarter of a beat) — tight, percussive delays.
Beat interval to BPM and note durations
When you tap along to a song or measure the time between drum hits, you get a beat interval in milliseconds. This calculator converts that interval to BPM and gives you derived note durations — the exact delay times needed for rhythmically synchronized audio effects.
How to use
Enter the beat interval in milliseconds — the average gap between two consecutive beats. For example: 500 ms for 120 BPM (quarter note = half a second).
These assume the beat note is a quarter note — the standard for most DAWs and time signatures. For compound time (6/8, 12/8), your "beat" is a dotted quarter note = 3 eighth notes; convert accordingly.
BPM to milliseconds reference table
BPM
Quarter note (ms)
Eighth note (ms)
Sixteenth (ms)
Dotted quarter (ms)
60
1000
500
250
1500
80
750
375
187.5
1125
100
600
300
150
900
120
500
250
125
750
140
428.57
214.29
107.14
642.86
160
375
187.5
93.75
562.5
180
333.33
166.67
83.33
500
Setting delay times by ear
The most common use of tap tempo math is dialing in delay pedals and DAW send effects rhythmically. A delay set to the eighth-note value produces a clean "doubling" at half-time; dotted-eighth delays (not shown directly, but = beat × 3/4) create the signature U2-style slapback.
Example at 100 BPM:
Quarter: 600 ms — standard echo
Dotted quarter: 900 ms — wide, spacious feel
Eighth: 300 ms — tight doubling
Dotted eighth: 450 ms — rhythmically syncopated
Finding the interval without a timer
If you know the BPM and need to verify it by feel, listen for the beat and calculate:
beat interval (ms)=BPM60,000
At 120 BPM: $60{,}000 / 120 = 500$ ms. Count "one thousand" — that is approximately one second (1,000 ms), or two beats.
Reverb pre-delay
Pre-delay in reverb plugins is usually set in milliseconds. A pre-delay matching an eighth note (or shorter) lets the dry signal breathe before the tail washes in. At 120 BPM, an eighth-note pre-delay is 125 ms; a sixteenth is 62.5 ms.
LFO sync in modulation effects
Many chorus, flanger, and tremolo effects express their rate in Hz rather than BPM. Converting:
LFO Hz=60BPM
At 120 BPM: LFO = 2 Hz (one cycle per half note). At 60 BPM: LFO = 1 Hz (one cycle per whole note).
Frequently Asked Questions (FAQ)
How do I measure the beat interval accurately?
Tap a button on a metronome app twice in time with the beat, or use your DAW's tap-tempo feature — it averages several taps. Alternatively, record a click and measure the distance between transients in your waveform editor.
What if my tempo is not a round number?
Enter the decimal interval directly. For example, 90.5 BPM corresponds to $60{,}000 / 90.5 \approx 662.98$ ms — enter 662.98 and the BPM field will show 90.50.
Why are only half, eighth, and sixteenth notes shown?
These are the most common delay subdivisions. Quarter-note duration is the input itself. Dotted notes, triplets, and other subdivisions can be derived: dotted eighth = eighth × 1.5; triplet eighth = quarter / 3.
