Flex Time in Logic Pro: Fix Audio Timing Cleanly
Move a late note or loose phrase without dragging the rest of the performance—or leaving stretched, hollow audio behind.
Flex Time in Logic Pro lets you move a note, beat, or phrase inside an audio region without cutting the recording into pieces. Using it cleanly has little to do with dragging a waveform around until it lines up. You choose the algorithm that suits the source, check the transient, put boundaries around the event, make the smallest move that does the job, then compare what you have against the untouched take.
That boundary step is what stops one late word from dragging the previous breath and the next consonant along with it. It also explains most Flex Time surprises: every marker you move compresses audio on one side and expands audio on the other, and it keeps going until Logic reaches another flex marker, a tempo marker, or the region edge.
Checked August 10, 2026: the controls, algorithm behavior, marker gestures, reset commands, and region settings below were verified against Apple’s current Logic Pro for Mac 12.3 guide. Older tutorials may show a combined Flex & Follow control; the current interface separates the region’s Flex checkbox from its Smart Tempo setting.
Use Flex Time for the right problem
| Problem | Best starting tool | Why |
|---|---|---|
| One late vocal word or bass note | Manual flex markers | You can isolate and move one attack. |
| Whole audio performance is uneven against a grid | Flex-enabled audio quantization | Automatic quantize can process many detected events consistently. |
| Imported loop should follow project tempo | Region Flex and Smart Tempo controls | The relationship is tempo-wide, not one-note repair. |
| Note is sharp or flat | Flex Pitch | The defect is pitch, not timing. |
| Entire take is globally early or late | Move the region or adjust region delay | No internal time stretching is needed. |
| Multimic drums need tightening | Grouped, Quantize-Locked Flex tracks | Every microphone must keep the same timing relationship. |
The companion guide to quantizing audio and MIDI in Logic Pro handles grids, Q-Strength, Q-Range, and phase-locked drum quantization. What follows here stays with manual Flex Time repair: one audible mistake, one controlled edit.
If the waveform itself is clipped, noisy, or captured through the wrong monitoring path, stretching it only puts the damage on display. Go through the Logic Pro audio recording workflow first, before you treat Flex Time as a rescue tool.
A safe Flex Time workflow
- Duplicate the audio region or save a project alternative before editing.
- Listen in the arrangement and identify one timing event that needs to move.
- Show Flex, enable Track Flex, and choose an algorithm that matches the source.
- Confirm the region's Flex checkbox and Smart Tempo setting permit the intended manual or tempo-follow behavior.
- Check that the transient marker sits on the actual attack you want to move.
- Add the target flex marker and neighbouring guard markers so the edit has safe boundaries.
- Drag the target marker only far enough to solve the timing problem.
- Listen for attack smearing, doubling, gaps, metallic tone, pitch change, and phase damage.
- Reduce the move, change the algorithm, repair markers, or reset the edit if quality gets worse.
- Compare against the untouched region in the full arrangement before keeping the change.
Don’t start in solo unless you’re hunting for a click or a transient. Timing is relational: the vocal has to land against the rhythm section, the bass against the kick, a double against the lead. Solo earns its keep when you’re checking for artifacts after a move; it’s a poor place to decide where the performance belongs.
Turn on Flex Time and confirm the region
- Choose Edit > Show Flex Pitch/Time in the Tracks area, or press Command-F.
- Click the Track Flex button on the audio track.
- Choose a Flex Time algorithm from the Flex Mode pop-up menu.
- Select the audio region and make sure its Flex checkbox is enabled in the Region inspector.
Apple’s current Flex Time overview says choosing an algorithm analyzes the track’s audio for transients—significant peaks that Logic treats as candidate timing events. Those thin analysis lines don’t change anything on their own. The timing only moves once you add or drag flex markers, apply audio quantization, or ask the region to follow tempo.
Why do older videos say Flex & Follow? That was the combined region menu in earlier versions. In Logic Pro 12.3, the current audio region parameters expose a Flex checkbox and a separate Smart Tempo menu. There’s no point hunting for an old label when the controls you need are already sitting in the inspector.
Choose the Flex Time algorithm by source
| Algorithm | Best first use | What to watch |
|---|---|---|
| Automatic | Quick initial classification | Logic selects Monophonic, Slicing, or Polyphonic; still audition the choice. |
| Slicing | Drums and non-tonal percussion | Slices play at original speed, so moved hits can expose gaps or tails from neighbouring slices. |
| Rhythmic | Rhythm guitar, rhythmic keys, loops | Looped material fills expansion; bad loop length or offset can repeat pre-attacks. |
| Monophonic | Dry vocal, bass, one-note melody | Reverb, doubles, or overlapping notes confuse the single-line assumption. |
| Polyphonic | Chords, piano, choir, complex mix | Phase-vocoder stretching can sound watery on attacks and costs more processing. |
| Speed (FX) | Creative slow-down or speed-up | Pitch changes with playback speed; it is not a transparent timing repair. |
| Tempophone (FX) | Granular, mechanical effects | The audible artifacts are the point, controlled by Grain Size and Crossfade. |
Treat these as starting points rather than genre rules. A plucked bass can work in Monophonic with Percussive enabled to protect its attacks. A wet lead vocal often behaves better in Polyphonic, since its reverb breaks the dry, one-note assumption. Apple’s current algorithm reference describes Automatic’s choices and every mode’s processing parameters, but what passes or fails is still the recorded sound.
Understand the markers before dragging
- Transient marker: an analysis line on a significant peak. It suggests where an event starts but does not change timing by itself.
- Flex marker: a manual timing anchor. Moving it compresses and expands audio inside the neighbouring boundaries.
- Quantize flex marker: an automatically created marker showing where audio quantization stretched the region.
- Tempo marker: a timing boundary connected to the region’s tempo behavior.
A transient marker can simply be wrong. Breaths, pick noise, spill, consonants, and reverberation all throw a line before or after the musical attack. When the candidate line sits somewhere other than the sound you hear as the note start, repair the transient analysis or drop a flex marker at the right waveform position. Snapping precisely to a bad marker still gives you a bad edit.
Keep analysis and intention apart: transient markers report what Logic detected, while flex markers record what you decided to control.
Add one marker or three guard markers
Logic’s waveform has two useful marker gestures:
- Click the upper half over or beside a transient to add one flex marker.
- Click the lower half to add three markers: the target and anchors at the previous and following transient positions.
Apple documents both in its current flex marker workflow. For local repair the three-marker gesture is the safer default, because those outer markers keep the surrounding phrase out of it. A single marker is enough when the region boundaries or existing anchors already fence off exactly the area you want to stretch.
Think in syllables and attacks. For a late vocal word, put guards around the previous stable vowel or breath boundary and the consonant that follows. On bass, protect the note attacks either side. On rhythm guitar, protect strums instead of arbitrary grid lines.
Move the event and understand the stretch
Drag a flex marker left and that event lands earlier. Logic compresses the material before it and expands the material after it, all the way out to the surrounding markers, tempo markers, or region edges. Drag right and the relationship flips. That’s why an unguarded move can touch far more audio than the marker seems to represent.
Move the attack to the musical reference—not automatically to the nearest vertical line. Dragging over an adjacent track lets you use the yellow guideline to snap the flex marker onto one of that track’s transients. Handy for pinning a bass note to a kick or a backing-vocal consonant to the lead, though only when those events genuinely belong together.
Hold Option while dragging a flex marker and you move the marker itself, with no time stretching. That shifts the anchor position rather than the audio timing, which is what you want when the marker landed on the wrong part of the waveform.
Flex Time, the Flex checkbox, and Smart Tempo
Manual markers and tempo following solve problems at different scales. The region’s Flex checkbox is what lets manual Flex edits and quantization affect playback. Its Smart Tempo setting governs how the region takes part in project-tempo behavior:
- Off ignores file tempo.
- On uses the file tempo as a reference.
- On + Align Bars also aligns bar positions.
- On + Align Bars and Beats adds beat alignment.
Do not turn on the most aggressive alignment setting as a repair for one late note. You’re asking Logic to solve a region-wide tempo relationship instead. Manual flex markers handle a local event, audio quantization handles many grid-related events, and Smart Tempo alignment is for imported or freely played audio that needs to track the project’s tempo map.
Practical source workflows
Vocals
Choose the performance before you repair it; the Take Folder and Quick Swipe comping workflow keeps that decision recoverable. Then start with Monophonic on a dry, single lead. Put the target on the consonant or vowel onset you actually hear as the word’s arrival, guard the adjacent breath and the next syllable, and try Polyphonic if ambience or doubles smear. Never let a word land neatly on screen while its consonant sounds doubled.
Bass
On a clean single-note line, try Monophonic with Percussive enabled whenever attacks need protection. Align only the notes whose relationship with the kick distracts you. Sliding notes, hammer-ons, and expressive pickups want a larger protected phrase, or no edit at all.
Rhythm guitar and keys
Rhythmic makes a useful first comparison, since it fills expanded gaps by looping material between slices. Listen for repeated pick noise or a pre-attack creeping into the loop; Loop Offset is there to move that looped area earlier. Chord-rich sustained material often does better in Polyphonic.
Drums and percussion
Slicing preserves each slice’s playback speed, which protects drum pitch and attack but can leave gaps once things move. Handle Fill Gaps, Decay, and Slice Length with care. A multimic kit is one performance: work with grouped, Quantize-Locked edits and verified Q-Reference tracks, never independent Flex moves on the snare close mic while the overheads stay put.
Diagnose Flex Time artifacts
| What you hear | Likely cause | First correction |
|---|---|---|
| Soft or doubled attack | Marker is off the true transient or the stretch crosses an attack. | Reposition the marker, add guards, and shorten the move. |
| Watery or metallic chord | Large Polyphonic phase-vocoder stretch. | Reduce the distance, add boundaries, or use an alternate take. |
| Click or gap between drum hits | Slicing created uncovered space. | Adjust Fill Gaps, Decay, or Slice Length; reduce the move. |
| Repeated pick or pre-attack | Rhythmic loop includes the next transient. | Adjust Loop Offset and loop length. |
| Vocal glitch at every marker | Percussive protection or Monophonic mode does not suit the source. | Disable Percussive or compare Polyphonic. |
| Pitch changes with timing | Speed (FX) is selected. | Choose a repair-oriented algorithm unless pitch change is intentional. |
| Hollow multimic drums | Microphone tracks moved differently. | Revert and edit the phase-locked group together. |
| Whole region shifts unexpectedly with tempo | Smart Tempo alignment scope is broader than intended. | Review the region’s Smart Tempo setting and use manual markers for local repair. |
There’s no universal safe stretch percentage. A clean bass note can shrug off a move that ruins a cymbal wash; a consonant may survive compression yet reveal a double when expanded. Once a repair needs an audible stretch, the professional answer is often a better take, a conventional region edit with crossfades, or leaving the human timing alone.
Delete, neutralize, or reset the edit
Flex work is recoverable, though the scope of the reset matters. Apple’s current marker reset guide separates these actions:
- Double-click a flex marker, click its x, or choose Delete Flex Marker to remove one marker and let surrounding boundaries determine the remaining stretch.
- Choose Set to Neutral Position to move the marker to the position the audio sample would occupy if that marker were deleted.
- Choose Reset Manual Flex Edits to remove manually added markers while leaving automatic quantize work intact.
- Choose Reset All Flex Edits to remove manual edits and automatic quantize flex markers.
Be careful with the Eraser tool: use it in the waveform body to remove flex markers. Apple warns that using it in the region header deletes the entire region. A duplicate region or a project alternative keeps recovery independent of Undo history, and the Logic Pro backup workflow covers that larger safety net.
Final Flex Time checklist
- The original region remains recoverable.
- The edit solves an audible timing problem in the arrangement.
- The algorithm matches the source better than Automatic’s first guess.
- The transient marker sits on the real musical attack.
- Guard markers protect the audio that should not move.
- The target moved only as far as necessary.
- Attacks, tails, ambience, and pitch remain believable.
- Multimic phase relationships are intact.
- The Flex checkbox and Smart Tempo setting match the intended scope.
- The edited version wins against the untouched take in the full section.
Follow the Logic Pro recording and editing hub to see this repair sit after capture and comping and before commit, inside the broader Logic Pro Tutorials path. If the timing trouble came from monitoring delay rather than the performance, fix the cause with the Logic Pro latency diagnostic before you record another take.
Frequently asked questions
What does Flex Time do in Logic Pro?
Flex Time changes the timing of audio by compressing or expanding material between flex markers, tempo markers, or region boundaries. It can move a note, align a phrase, follow project tempo, or support audio quantization without cutting the region into ordinary edits.
How do I turn on Flex Time in Logic Pro?
Choose Edit > Show Flex Pitch/Time or press Command-F, click the Track Flex button on the audio track, then choose a Flex Time algorithm from the Flex Mode menu. In Logic Pro 12.3, confirm the selected region's Flex checkbox is enabled.
Which Flex Time algorithm should I use?
Start with Slicing for drums and non-tonal percussion, Monophonic for a relatively dry vocal or single-note instrument, Rhythmic for rhythm guitar or keyboard, and Polyphonic for chords or a complex mix. Use Speed and Tempophone as creative effects, not transparent repair modes.
What is the difference between a transient marker and a flex marker?
A transient marker is an analysis point marking a likely attack or significant peak. A flex marker is an edit anchor you create or move to change timing. Automatic audio quantization can also create quantize flex markers.
Why does moving one flex marker change audio on both sides?
The moved marker creates compression on one side and expansion on the other until Logic reaches neighbouring flex markers, tempo markers, or the region edges. Add guard markers around the target first when the surrounding timing must stay fixed.
Why does Flex Time sound metallic, doubled, or watery?
Common causes are the wrong algorithm, an incorrect transient, a stretch that is too large, reverberant material in Monophonic mode, phase-sensitive tracks edited separately, or exposed gaps in Slicing mode. Reduce the move, repair the marker, or change algorithms.
How do I remove Flex Time edits?
Delete an individual flex marker to remove or redistribute its local change. Control-click the region and choose Reset Manual Flex Edits to remove manual work, or Reset All Flex Edits to remove manual and automatically created quantize markers.
Is Flex Time the same as Flex Pitch or Smart Tempo?
No. Audio timing belongs to Flex Time. Flex Pitch analyzes and corrects note pitch, while Smart Tempo manages tempo relationships. A region's Flex checkbox and Smart Tempo setting can connect Flex processing to project tempo, so the systems can interact without being the same tool.
