Use alignment guides in Keynote on Mac
Use alignment and spacing guides to help you place objects precisely. When guides are turned on, they appear as you drag an object on a slide in alignment with, or equidistant to, another object. You can turn the guides off and on as needed.
You can also add your own horizontal or vertical alignment guides and place them anywhere on a slide. These persistent alignment guides don’t appear and disappear as you drag objects, but remain visible while you’re working.
Turn on alignment guides
Choose Keynote > Preferences (from the Keynote menu at the top of your screen), then click Rulers at the top of the preferences window.
Select any of the options:
Show guides at object center: Guides appear when an object’s center aligns with another object’s center or the center of the slide.
Show guides at object edges: Guides appear when an object’s edges align with another object’s edge or an edge of the slide.
Show guides for relative sizing: Guides appear when an object matches another object’s size in a particular dimension (for example, height).
Show guides for relative spacing: Guides appear when three or more objects are placed equally apart in a line.
You can also change the color of the alignment guides. Click the color well next to Alignment Guides in Rulers preferences, then choose a color.
Add persistent alignment guides
You can add alignment guides that remain visible on the slide while you’re working, even if you leave the slide and return to it later. You can add as many guides as you like and position them to suit your needs. Alignment guides are unique to each slide in a presentation.
If you don’t see rulers, click in the toolbar, then choose Show Rulers.
Move the pointer over the vertical or horizontal ruler, then drag to the slide.
To change the location of an alignment guide, drag it.
Remove, hide, or clear persistent alignment guides
Do any of the following:
Remove a horizontal guide: Drag it up and off the slide.
Remove a vertical guide: Drag it to the left and off the slide.
Hide all guides: Choose View > Guides > Hide Guides (from the View menu at the top of your screen, not the View button in the toolbar).
To show all guides again, choose View > Guides > Show Guides.
Clear all guides: Choose View > Guides > Clear All Guides on Slide.
Change the color of alignment guides
Choose Keynote > Preferences (from the Keynote menu at the top of your screen), then click Rulers.
Click the color well next to Alignment Guides, then choose a color.
Tip: You can add a button to the toolbar to show and hide guides.