tempocalculator

Tempo Change Calculator: BPM Difference in Percent

Going from 124 to 128 BPM is a tempo change of +3.23%, a difference of 4 BPM. Enter a starting and a target tempo and the tempo change calculator shows the percent change to set on a pitch fader, the BPM difference, and whether that change fits a ±6%, ±8%, ±10%, ±16% or ±50% fader range.

Both tempos from 20 to 300 BPM.

Tempo change

+3.23%

pitch-fader setting

Difference

+4

BPM

Going from 124 to 128 BPM is a change of +3.23%.

Does the change fit your pitch-fader range?
Fader rangeFits?
±6%Yes
±8%Yes
±10%Yes
±16%Yes
±50%Yes

change % = (target − start) ÷ start × 100

How is a tempo change calculated in percent?

Subtract the starting BPM from the target, divide by the starting BPM, and multiply by 100. The percentage is always relative to where you start, which is how pitch faders on turntables and DJ players are labeled.

change % = (target − start) ÷ start × 100

Because the base is the starting tempo, the same BPM gap gives different percentages in each direction. Speeding 120 up to 128 BPM is +6.67%; slowing 128 down to 120 BPM is −6.25%.

How to use the calculator

  1. Enter the starting tempo

    Type the tempo of the track as it plays now in Starting tempo (BPM).

  2. Enter the target

    Type the tempo you want to reach in Target tempo (BPM). Both fields accept 20 to 300 BPM with two decimals.

  3. Read the change

    Tempo change gives the pitch-fader setting in percent; Difference gives the gap in BPM.

  4. Check the fader table

    Each fader range row reads Yes when the change fits and No — out of range when it does not.

For a track without a known tempo, measure it first with the song BPM finder.

Worked examples: common tempo jumps

Wider tempo gaps need wider fader ranges. Each row uses the formula above and the tool's five ranges.

Tempo changes and the smallest fader range that covers them
From → toDifferenceChangeSmallest fitting range
126 → 128 BPM+2 BPM+1.59%±6%
128 → 124 BPM−4 BPM−3.12%±6%
120 → 128 BPM+8 BPM+6.67%±8%
128 → 140 BPM+12 BPM+9.38%±10%
90 → 100 BPM+10 BPM+11.11%±16%

Who uses a tempo percentage

Anyone who changes speed with a control labeled in percent. Common cases:

  • DJs read the percentage straight onto the pitch fader to beatmatch two records; the guide on beatmatching and pitch-fader math explains the workflow.
  • Remixers judge how far an acapella must be stretched to fit a new instrumental.
  • Musicians practicing with a slowed-down recording set playback to −10% or −20% and know the exact tempo that results.
  • Producers gauge how noticeable a tempo change is before committing to it.

Without key lock, a tempo change also shifts pitch. The tempo-to-semitones calculator converts the same two tempos into semitones and cents.

What the calculator does not account for

It measures the change; it does not know your equipment. Fader ranges differ between devices, and some players offer several switchable ranges, so check which setting is active. The fader table compares the size of the change only. It does not consider key clashes, which grow with the percentage, or the audio quality of large time-stretches. For a change larger than ±50%, the half-time or double-time value is usually the better match; the half-time and double-time chart lists them.

Questions

What percent is 120 to 125 BPM?

+4.17%. (125 − 120) ÷ 120 × 100 = 4.17.

Why is slowing down a smaller percentage than speeding up?

Because the base changes. The percentage divides by the starting tempo, and a faster start makes the same BPM gap a smaller share.

Can I mix 128 BPM with 174 BPM?

Not on a ±16% fader: the change is +35.94%. Only the ±50% range covers it, and the pitch rises by 5.32 semitones without key lock.