Tempo Converter

Italian tempo markings are the words at the top of a score: Largo, Andante, Allegro. They tell a performer how fast to play, and they have done so since roughly the seventeenth century, when Italian was the working language of European music.

They are ranges, not numbers, and that is on purpose

Before Maelzel patented the metronome in 1815 there was no way to write down an exact tempo, so composers wrote a word and trusted the player. The words survived the metronome, because they carry something a number cannot: Grave means solemn as well as slow, Vivace means lively as well as fast. A score marked Allegro at 132 and one marked Vivace at 132 want different playing.

This is also why no two sources agree on the ranges. The table this calculator uses is a common modern convention, but you will find Andante quoted anywhere from 56 to 108 depending on who is writing. Historical usage drifted too: an eighteenth-century Allegro is usually slower than a twentieth-century one. When a score gives a metronome mark, the number wins over the word.

Modifiers that change everything

The words rarely appear alone. Allegro ma non troppo is fast but not too much so. Poco means a little, molto a lot, assai very. Andantino is the awkward one: the diminutive ought to mean slightly slower than Andante, but by the nineteenth century most composers used it to mean slightly faster, and Beethoven himself complained about the ambiguity in a letter.

Then there are the changes: ritardando and rallentando slow down, accelerando speeds up, a tempo returns to the previous speed, and rubato means stealing time from one note to give it to another, which is a licence rather than an instruction.

Beats per minute to milliseconds

For anyone setting a delay or a reverb pre-delay rather than reading a score, the conversion is one division:

Milliseconds per beat = 60,000 ÷ BPM

One minute is 60,000 milliseconds, so at 120 BPM a quarter note lasts 500 ms. Halve it for an eighth, quarter it for a sixteenth, and multiply by 1.5 for a dotted value. The calculator prints those alongside the tempo marking. For the full set of subdivisions and triplets, the Delay Time Calculator covers it properly.

Reverb pre-delay is the odd one out. It wants a much shorter subdivision than a delay does, a 32nd note rather than a 16th, which at 120 BPM is 62 ms against 125. Anything as long as a 16th and the tail starts to read as a second hit instead of as space around the source.