BPM2MS2HZ — User Manual

01Three editions

All three editions compute the same numbers with the same formulas. They differ only in where the tempo comes from and how you read the result.

02Install

The web edition needs nothing. For REAPER:

1. Install ReaPack (one file into the UserPlugins folder, restart REAPER).
2. Extensions → ReaPack → Import repositories…, paste
   https://raw.githubusercontent.com/timtechlor/reapack-TimTechlor/main/index.xml
3. Extensions → ReaPack → Browse packages, search for BPM2MS2HZ Calculator, install, Apply.
4. The window edition needs ReaImGui (“ReaImGui: ReaScript binding for Dear ImGui”, repository ReaTeam Extensions, which ReaPack ships with). Install it the same way and restart REAPER.
5. Run it from Actions → Show action list → search “BPM2MS2HZ”. Bind it to a key or a toolbar button if you use it often.

03Reading the table

ms  = 60000 / BPM × beats      (1 beat = 1 quarter note)
Hz  = 1000 / ms

The note table runs from 1/1 to 1/32. The web and console editions list bars from 1 to 32 and assume 4/4; the REAPER window goes up to 64 bars and lets you pick the time signature.

Example at 128 BPM: one beat is 60000 / 128 = 468.75 ms, so 1/4 reads 468.8 ms and 2.133 Hz, and one bar is 1.875 s.

04In practice

Delay times

Read the MS column and type the value into a delay that has no host sync. At 128 BPM the dotted eighth (1/8., 351.6 ms) is the classic ping-pong spacing; a plain 1/4 is 468.8 ms.

LFO rates

The HZ column is the LFO speed that locks to the grid: at 128 BPM, 1/4 = 2.133 Hz and 1/16 = 8.533 Hz. Auto-pan, tremolo and filter sweeps then move with the track instead of drifting against it.

Release and sidechain

Whole bars come as seconds: 1 bar = 1.875 s at 128 BPM. A compressor release of one bar keeps the pump breathing with the track instead of choking it; for a tight kick duck, start from the 1/8 or 1/16 value.

05Web edition

• Tempo — type it into the BPM field or drag the slider. The table updates live.
• TAP — tap along with the beat; the tempo is averaged over the last taps. A pause of more than three seconds starts a new measurement.
• COPY — copies the console table as text.
• Popup — opens a compact window with only the tempo input and the live table, to pin next to your DAW.

06REAPER window

• Tempo follows the project by default (checkbox “from project”). Touching the slider switches to a manual tempo; tick the checkbox again to go back to sync.
• Click any value to copy it to the clipboard, then paste it into the plug-in field.
• Tabs — NOTE VALUES (1/1 to 1/32, dotted, triplets) and BARS (up to 64 bars, selectable time signature).
• OPTIONS (top right) — UI font size, show or hide dotted and triplet variants, wordmark watermark. All settings are saved permanently.

07Troubleshooting

• The window does not open and REAPER reports a missing ImGui function — ReaImGui is not installed, or REAPER was not restarted after installing it (section 02).
• The console edition prints “No valid project tempo found.” — open or create a project and run it again.
• The values do not match a tempo change later in the song — the scripts use the tempo REAPER reports as current when they read it. For a section with a different tempo, set that tempo manually in the window (or in the web edition).
• COPY does nothing in the browser — the browser blocked clipboard access; open the page directly (not inside a frame) and allow clipboard access.