Use ACF image field as avatar

functions.php

<?php
/**
 * Use ACF image field as avatar
 * @author Mike Hemberger
 * @link http://thestizmedia.com/acf-pro-simple-local-avatars/
 * @uses ACF Pro image field (tested return value set as Array )
 */
add_filter('get_avatar', 'acf_profile_avatar', 10, 5);
function acf_profile_avatar( $avatar, $id_or_email, $size, $default, $alt ) {
    if ( is_numeric( $id_or_email ) ) {
        $id   = (int) $id_or_email;
        $user = get_user_by( 'id' , $id );
    } elseif ( is_object( $id_or_email ) ) {
        if ( ! empty( $id_or_email->user_id ) ) {
            $id   = (int) $id_or_email->user_id;
            $user = get_user_by( 'id' , $id );
        }
    } else {
        $user = get_user_by( 'email', $id_or_email );
    }
    if ( ! $user ) {
        return $avatar;
    }
    $user_id = $user->ID;
    $image_id = get_user_meta($user_id, 'avatar', true); // CHANGE TO YOUR FIELD NAME
    if ( ! $image_id ) {
        return $avatar;
    }
    $image_url  = wp_get_attachment_image_src( $image_id, 'thumbnail' ); // Set image size by name
    $avatar_url = $image_url[0];
    $avatar = '<img alt="' . $alt . '" src="' . $avatar_url . '" class="avatar avatar-' . $size . '" height="' . $size . '" width="' . $size . '">';
    return $avatar;
}



add_filter('get_avatar_url', 'acf_profile_avatar_url', 10, 3);
function acf_profile_avatar_url($url, $id_or_email, $args){
    if ( is_numeric( $id_or_email ) ) {
        $id   = (int) $id_or_email;
        $user = get_user_by( 'id' , $id );
    } elseif ( is_object( $id_or_email ) ) {
        if ( ! empty( $id_or_email->user_id ) ) {
            $id   = (int) $id_or_email->user_id;
            $user = get_user_by( 'id' , $id );
        }
    } else {
        $user = get_user_by( 'email', $id_or_email );
    }
    if ( ! $user ) {
        return $url;
    }
    $user_id = $user->ID;
    $image_id = get_user_meta($user_id, 'avatar', true); // CHANGE TO YOUR FIELD NAME
    if ( ! $image_id ) {
        return $url;
    }
    $image_url  = wp_get_attachment_image_src( $image_id, 'thumbnail' ); // Set image size by name
    $avatar_url = $image_url[0];
    return $avatar_url;
}