How long is one beat at a given BPM?

One beat lasts 60000 divided by the BPM in milliseconds. At 90 BPM a beat is about 667 ms, so a 4/4 bar is about 2667 ms and a two-bar loop is about 5333 ms long.

Why slice into 8, 16, or 32 equal pieces?

Powers of two line up with the beat grid. Sixteen slices over a one-bar 4/4 loop gives one slice per sixteenth note, so every chop falls on a musical division and stays in time when you rearrange them.

What are the sample numbers for?

Sample-accurate editors and hardware samplers cut at sample positions, not just milliseconds. The tool converts each boundary to a sample index at 44.1 kHz so your cuts land exactly on the grid with no drift.

Does this work for triplet or odd time signatures?

Yes for whole-bar loops. Set the beats per bar to match the meter, such as 3 for 3/4. For triplet chops, set the slice count so it divides the loop into triplet groupings, for example 12 or 24 over a 4/4 bar.

What if my loop is not an exact number of bars?

Then it will not slice cleanly to a tempo grid. Trim or time-stretch the loop to a whole number of bars at the target BPM first, then use this tool to find even, on-grid cut points.

Sample Chop BPM Grid Calculator

Chopping a sampled loop into even slices is the heart of MPC-style production, but the cuts only stay in time if they land exactly on the beat grid. This tool does the arithmetic: enter the tempo, bar count, and how many slices you want, and it prints every cut point in both milliseconds and samples.

How it works

A loop of a whole number of bars at a fixed tempo has an exact length, which divides evenly into equal slices:

beat (ms)   = 60000 / BPM
bar (ms)    = beat × beats per bar
loop (ms)   = bar × bars
slice (ms)  = loop / slice count
boundary i  = i × slice (ms)
sample #    = (ms / 1000) × 44100

Because every boundary is an exact fraction of the loop, the slices line up with the underlying grid, so you can reorder them, drop some, or repeat others and the groove stays locked to the tempo.

Tips and example

A two-bar 4/4 loop at 90 BPM is about 5333 ms long; sliced into 16 pieces, each chop is roughly 333 ms — one eighth note — perfect for rearranging a drum break. Always trim your source so it is an exact number of bars at the target BPM before slicing; even a few stray milliseconds at the loop point will smear every cut and make the rearranged pattern drift out of time.