Song Length Calculator
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What Your Result Means
- Duration: The total playback time at constant tempo. For example, 4 minutes 32 seconds means your song plays for that exact length at the BPM you specified.
- Total Beats: Number of beats the time signature defines across all measures. In 4/4 time with 32 measures, that is 128 total beats.
- Beats per Second: How fast individual beats occur — useful for syncing to video frame rates. At 120 BPM, beats occur 2 times per second (120 ÷ 60).
- Beat Unit Adjustment: A 6/8 time signature plays faster than 6/4 at the same BPM because eighth notes are shorter than quarter notes. The beat unit converts the denominator to quarter-note equivalents.
How This Calculator Works
The calculator multiplies the number of measures by the time signature numerator to get total beats. It then adjusts for the denominator by converting to quarter-note equivalents. Finally, it divides the total quarter notes by the BPM and multiplies by 60 to get seconds, which are displayed as minutes and seconds.
Quick Questions
What does BPM mean?
BPM stands for beats per minute. It measures the tempo or speed of a song. For example, 120 BPM means the song has 120 beats in one minute, or 2 beats per second.
How does time signature affect the duration?
The time signature's denominator affects beat length. The numerator tells how many beats per measure. A 4/4 song at 120 BPM will be twice as long as a 4/8 song with the same number of measures, because eighth notes are half the length of quarter notes.
Why doesn't my duration match my DAW?
This calculator assumes constant tempo throughout the song. If your DAW shows a different duration, check for tempo changes, fermatas (holds), ritardandos (slowing), or accelerandos (speeding up) that would change the actual time.
How can I account for tempo changes?
Calculate each section separately at its own BPM and number of measures, then add the durations together. For example, a 16-measure intro at 100 BPM plus a 32-measure verse at 110 BPM would be calculated as two separate runs.
What about pickup measures?
A pickup measure (anacrusis) is an incomplete measure at the beginning of a song. Count it as a fractional measure — if it has 2 beats out of 4, count it as 0.5 measures.
Sources
- Wikipedia — Tempo (BPM definition and standard tempos)
- Wikipedia — Time Signature (numerator/denominator meaning and beat grouping)
- musictheory.net — Time Signatures (interactive time signature lessons)
Method & review
Estimate only. Results reflect your inputs and standard formulas. Double-check important decisions independently.