To make uneven recorded MIDI notes the same length in GarageBand on Mac, resize each note to a chosen duration in the Piano Roll Editor. Apple documents that resizing multiple selected notes preserves their length differences, so that operation does not equalize them.
This workflow is for a recorded MIDI region on a software instrument track. It keeps your existing notes and lets you decide whether to preserve their recorded start times or align those starts before adjusting durations. Apple’s note-editing documentation supports individual resizing and explains the limitation of resizing a selection.
What GarageBand’s documented controls can do
Apple documents two relevant resizing actions: drag either edge of an individual note, or select several notes and drag an edge of one selected note. For the second action, the differences between the selected notes’ lengths remain. Making the selection shorter or longer therefore leaves uneven durations uneven. See Edit notes in the Piano Roll Editor in GarageBand on Mac.
The current documentation does not describe a command that assigns one absolute duration to every selected recorded note. Apple’s editor keyboard-shortcut list also provides no shortcut for that outcome. The supported path described here is to set notes individually; do not assume that a modifier key or an undocumented bulk-resizing trick will produce equal lengths.
Choose the operation according to what actually needs changing:
| Your editing goal | Documented control | What to check |
|---|---|---|
| Give uneven notes one common duration | Resize each note individually | Each note reaches the target length |
| Lengthen or shorten an already equal-length group | Select the group and resize together | The notes remain equal in length |
| Correct when notes occur | Use Time Quantize |
Notes align with the intended timing divisions |
| Insert additional notes | Use the Insert note-value control and add notes |
The control concerns inserted notes, rather than assigning lengths to the existing recording |
These distinctions follow Apple’s descriptions of note resizing, timing quantization, and the Piano Roll Editor inspector.
Open the recorded notes and choose a target duration
Double-click the MIDI region in the Tracks area. Alternatively, select the software instrument track or MIDI region and choose View > Show Editor. Apple documents both methods for opening the Piano Roll Editor.
The editor displays MIDI notes as colored bars. Use its zoom controls to make short notes large enough to inspect comfortably. If you need more vertical working space, drag the bar at the top of the editor upward. These controls are described in Apple’s editor introduction.
Before dragging anything, choose a specific target: for example, an eighth note for every note in a short passage. Also decide whether every note should receive that duration. If a few notes intentionally need to last longer, leave those outside the editing pass.
Then decide what to do with the recorded start times. Equal duration does not require equal spacing. You can keep slightly irregular starts and give each note the same length, or correct the timing first and then edit lengths. Making that decision now avoids changing the rhythm when your intended task is only to standardize duration.
Resize each existing note to the same length
Apple documents that a help tag displays a note’s length while you resize it. Use that feedback as your reference, especially when recorded notes begin between ruler divisions. The documented gesture is to drag a note’s left or right edge horizontally. For this task, use the right edge so you adjust the endpoint while keeping the left edge in place. See Apple’s resizing instructions.
- Click the first note you want to change, without holding
Shift. Confirm that only the intended note is selected. - Place the pointer at its right edge and drag horizontally.
- Watch the length help tag and stop when the note reaches your chosen duration.
- Click the next note individually and repeat with the same target length.
- Work through the passage in time order, then inspect the completed notes again.
Selection matters because dragging an edge with several notes selected resizes the group. Apple documents ordinary clicking for selecting one note, and Shift-clicking or dragging a selection rectangle for selecting multiple notes. Use individual selection throughout an uneven passage. See Select notes and resize notes.
Avoid dragging the middle of a note when you intend to resize it: Apple documents dragging a selected note left or right as the operation for moving it. If a start position changes accidentally, immediately use Command-Z or Edit > Undo, then repeat the edge drag. Apple documents that undo action in Undo and redo edits in GarageBand on Mac.
Worked example: equal lengths with recorded starts preserved
Consider four synthetic notes, all at the same pitch, in a 4/4 passage. The following numbers are illustrative beat offsets from the beginning of the passage, with one beat representing a quarter note. They are arithmetic examples, not GarageBand help-tag text. The target is an eighth note, or 0.50 beat.
| Synthetic note | Recorded start | Original duration | Target duration | Required endpoint |
|---|---|---|---|---|
| A | 0.08 | 0.31 | 0.50 | 0.58 |
| B | 1.04 | 0.72 | 0.50 | 1.54 |
| C | 2.00 | 0.46 | 0.50 | 2.50 |
| D | 3.12 | 0.89 | 0.50 | 3.62 |
The decision rule is simple: endpoint equals start plus target duration. Note A must end at 0.58 to last 0.50 beat. Ending it at the nearby half-beat position, 0.50, would make its duration only 0.42 beat. This is why matching every endpoint to a convenient ruler division can produce inconsistent lengths when the starts remain irregular.
For the same reason, notes of equal duration do not necessarily end together. Compare their lengths and the resizing help tag, rather than expecting their right edges to form one vertical line. This example derives the endpoint calculation from the chosen target; it does not describe an automatic calculation performed by GarageBand.
Should you quantize before adjusting durations?
Use Time Quantize if you also want to correct the notes’ timing. Apple describes it as adjusting timing to a selected note value and provides controls for either whole MIDI regions or selected notes. Its documented purpose does not establish a way to assign every existing note the same duration. See Quantize note timing in the Piano Roll Editor in GarageBand on Mac.
To quantize selected notes, select the intended notes, click Notes in the editor inspector, and choose the timing value from Time Quantize. If that value is already selected, Apple says to click the Q button to apply it to the selected notes. For an entire region, use Region and its Time Quantize controls; the Strength slider is available for regions, rather than individual-note selections. Follow Apple’s quantization procedure.
If your task includes both timing correction and equal durations, complete the timing decision first, then resize and verify the notes against their resulting starts. If you want to retain the recorded placement, proceed directly to individual resizing. Apple states that Time Quantize operates nondestructively for playback and that the original timing can be recalled by switching quantization off. See the documented quantization behavior.
Check the result and resolve common editing mistakes
Review one short section at a time. For each edited note, check its duration using the resizing feedback, confirm that its left edge remains where intended, and compare it with the next note. A uniform target may create overlaps wherever the spacing between starts is shorter than that target. Decide whether those overlaps fit the passage or whether those particular notes need an exception.
If the notes remain different lengths after a group drag, return to individual editing. That result follows Apple’s documented rule that bulk resizing retains length differences. If notes already have equal lengths, however, preserving those differences means a group resize can keep them equal. See Resize multiple notes.
If changing Insert seems to leave the recording untouched, check the purpose of the control. Apple describes it as choosing a note value for notes to insert. It is not documented as a duration assignment for selected recorded notes. For existing notes, return to edge resizing. See the inspector’s control descriptions.
Finish by playing the edited passage and checking any intentionally longer notes separately. For an uneven recording, the dependable documented workflow is to choose a duration, resize each note’s right edge using the length help tag, and verify its start and endpoint. Once the notes share a length, group resizing becomes useful for changing that common length together. Apple’s note-editing guide documents the behavior behind both stages.