How to count the total number of rows in a ACF repeater output

It's work for me, count must be placed before if(have_rows('repeater_field') :

Ternary operator to avoid warning errors if repeater is empty

If you place the count after "if(have_rows('repeater_field')) :", count returns FALSE

$repeater_field = get_sub_field('repeater_field');
// OR if repeater isn't a sub_field
// $repeater_field = get_field('repeater_field');

// ternary operator to avoid warning errors if no result
$count =  $repeater_field ? count($repeater_field) : FALSE;

if(have_rows('repeater_field')) : // OR if($count) :

    echo 'Number of posts:' . $count . '<br>';

    while(have_rows('repeater_field')) : the_row();
        echo get_sub_field('field_name') . '<br>';
    endwhile;
endif;

You can get the row count like this:

$count = get_post_meta(get_the_ID(), 'testimonials', true);

Obviously this uses get_the_ID() to retrieve the current post ID - you may need to amend this.

ACF stores the repeater count value against the repeater field name as the meta_key in the postmeta table.

ACF uses the count to retrieve the correct repeater subfield values, which are stored as values against meta_keys with the format $repeaterFieldname . '_' . $index . '_' . $subfieldName.

Hope this helps...

OK, I finally found the answer to this.

The way to count total rows in an ACF repeater is:

$numrows = count( get_sub_field( 'field_name' ) );