BPM, speed and duration calculator
Change the tempo to find the new duration, or start with a target duration to calculate the BPM you need. No file required.
- Works both ways
- Hundredth-second precision
- No account
Your calculation
Choose what you know and the result updates instantly.
Do not know the tempo?Find the BPM
Result
New duration
2:51.43
- Speed change
- +5 %
- faster
- Duration difference
- 0:08.57
- shorter
Small change
The change is moderate. Still check how vocals and transients sound.
Calculation used
3:00 × 120 ÷ 126 = 2:51.43
Mathematical result for a constant tempo. A track with tempo changes may need to be checked by ear.
MixClap removes or repeats musical sections to preserve the tempo and ending. Try free, export for €4.99.
Mix tracks at this tempoThe studio detects BPM and can synchronize transitions.
Transparent method
How to calculate BPM, speed, and duration
BPM is proportional to playback speed. Duration moves in the opposite direction: speeding up makes a track shorter, slowing down makes it longer.
Calculate the new duration
final duration = original duration × original BPM ÷ final BPM
Calculate the required BPM
required BPM = original BPM × original duration ÷ target duration
Moving from 120 to 126 BPM multiplies speed by 1.05, so it is a 5% increase. A three-minute song then lasts about 2 min 51.43 sec.
To hit a chosen duration, reverse the calculation. Taking a three-minute song down to 2 min 30 sec using speed alone would require moving from 120 to 144 BPM, a 20% increase.
This calculation describes a uniform speed or tempo change. It does not detect verses, choruses, or tempo changes inside the track.
Tempo change examples
These values use exactly the same formula as the calculator.
| Original BPM | Final BPM | Speed | Original duration | Final duration |
|---|---|---|---|---|
| 120 BPM | 126 BPM | +5 % | 3:00 | 2:51.43 |
| 128 BPM | 120 BPM | -6.25 % | 4:00 | 4:16 |
| 90 BPM | 100 BPM | +11.11 % | 3:30 | 3:09 |
Change speed or rebuild the duration?
Change the tempo uniformly
Useful when the whole track really should play faster or slower. Its structure stays the same and every section changes length.
Adjust the musical structure
Useful when you need a duration without warping the whole song. MixClap can remove or repeat sections and preserve a proper musical ending.
Frequently asked questions
How do I calculate song duration after a BPM change?
Multiply the original duration by the original BPM, then divide by the final BPM. For 180 seconds at 120 BPM changed to 126 BPM: 180 × 120 ÷ 126 = 171.43 seconds, or about 2 min 51.43 sec.
How do I calculate the BPM needed for an exact duration?
Multiply the original BPM by the original duration, then divide by the target duration. For example, changing 180 seconds to 150 seconds from 120 BPM would require 144 BPM.
Does speeding up by 5% remove exactly 5% of the duration?
No. Duration is divided by 1.05, so it falls by about 4.76%. That is why a three-minute song sped up by 5% lasts about 2 min 51.43 sec, not 2 min 51 sec.
Does changing BPM change the key?
Simple faster or slower playback changes pitch too. A time-stretching engine can preserve the key more closely, with quality depending on the track and the size of the change.
How much tempo change is acceptable?
There is no universal limit. A few percent can be subtle on some tracks; vocals, percussion, and larger changes often make it more obvious. Always listen to the result.
How is this different from the song length tool?
This calculator applies one uniform speed mathematically. MixClap’s length tool instead tries to remove or repeat musical sections so you can reach a duration without speeding up the whole track.