diff --git a/calendar/externallib.php b/calendar/externallib.php
index eccd04eb896..d7f83479954 100644
--- a/calendar/externallib.php
+++ b/calendar/externallib.php
@@ -1371,4 +1371,82 @@ class core_calendar_external extends external_api {
             ]
         );
     }
+
+    /**
+     * Convert the specified dates into unix timestamps.
+     *
+     * @param   array $datetimes Array of arrays containing date time details, each in the format:
+     *           ['year' => a, 'month' => b, 'day' => c,
+     *            'hour' => d (optional), 'minute' => e (optional), 'key' => 'x' (optional)]
+     * @return  array Provided array of dates converted to unix timestamps
+     * @throws moodle_exception If one or more of the dates provided does not convert to a valid timestamp.
+     */
+    public static function get_timestamps($datetimes) {
+        $params = self::validate_parameters(self::get_timestamps_parameters(), ['data' => $datetimes]);
+
+        $type = \core_calendar\type_factory::get_calendar_instance();
+        $timestamps = ['timestamps' => []];
+
+        foreach ($params['data'] as $key => $datetime) {
+            $hour = $datetime['hour'] ?? 0;
+            $minute = $datetime['minute'] ?? 0;
+
+            try {
+                $timestamp = $type->convert_to_timestamp(
+                    $datetime['year'], $datetime['month'], $datetime['day'], $hour, $minute);
+
+                $timestamps['timestamps'][] = [
+                    'key' => $datetime['key'] ?? $key,
+                    'timestamp' => $timestamp,
+                ];
+
+            } catch (Exception $e) {
+                throw new moodle_exception('One or more of the dates provided were invalid');
+            }
+        }
+
+        return $timestamps;
+    }
+
+    /**
+     * Describes the parameters for get_timestamps.
+     *
+     * @return external_function_parameters
+     */
+    public static function get_timestamps_parameters() {
+        return new external_function_parameters ([
+            'data' => new external_multiple_structure(
+                new external_single_structure(
+                    [
+                        'key' => new external_value(PARAM_ALPHANUMEXT, 'key', VALUE_OPTIONAL),
+                        'year' => new external_value(PARAM_INT, 'year'),
+                        'month' => new external_value(PARAM_INT, 'month'),
+                        'day' => new external_value(PARAM_INT, 'day'),
+                        'hour' => new external_value(PARAM_INT, 'hour', VALUE_OPTIONAL),
+                        'minute' => new external_value(PARAM_INT, 'minute', VALUE_OPTIONAL),
+                    ]
+                )
+            )
+        ]);
+    }
+
+    /**
+     * Describes the timestamps return format.
+     *
+     * @return external_single_structure
+     */
+    public static function get_timestamps_returns() {
+        return new external_single_structure(
+            [
+                'timestamps' => new external_multiple_structure(
+                    new external_single_structure(
+                        [
+                            'key' => new external_value(PARAM_ALPHANUMEXT, 'Timestamp key'),
+                            'timestamp' => new external_value(PARAM_INT, 'Unix timestamp'),
+                        ]
+                    )
+                )
+            ]
+        );
+    }
 }
diff --git a/calendar/tests/externallib_test.php b/calendar/tests/externallib_test.php
index d3a7cf9e779..810c25fdd20 100644
--- a/calendar/tests/externallib_test.php
+++ b/calendar/tests/externallib_test.php
@@ -2696,4 +2696,87 @@ class core_calendar_externallib_testcase extends externallib_advanced_testcase {
         );
         $this->assertEquals(['user', 'course', 'group'], $data['allowedeventtypes']);
     }
+
+    /**
+     * Test get_timestamps with string keys, with and without optional hour/minute values.
+     */
+    public function test_get_timestamps_string_keys() {
+        $this->resetAfterTest(true);
+        $this->setAdminUser();
+
+        $time1 = new DateTime('2018-12-30 00:00:00');
+        $time2 = new DateTime('2019-03-27 23:59:00');
+
+        $dates = [
+            [
+                'key' => 'from',
+                'year' => $time1->format('Y'),
+                'month' => $time1->format('m'),
+                'day' => $time1->format('d'),
+            ],
+            [
+                'key' => 'to',
+                'year' => $time2->format('Y'),
+                'month' => (int) $time2->format('m'),
+                'day' => $time2->format('d'),
+                'hour' => $time2->format('H'),
+                'minute' => $time2->format('i'),
+            ],
+        ];
+
+        $expectedtimestamps = [
+            'from' => $time1->getTimestamp(),
+            'to' => $time2->getTimestamp(),
+        ];
+
+        $result = core_calendar_external::get_timestamps($dates);
+
+        $this->assertEquals(['timestamps'], array_keys($result));
+        $this->assertEquals(2, count($result['timestamps']));
+
+        foreach ($result['timestamps'] as $data) {
+            $this->assertTrue(in_array($data['key'], ['from', 'to']));
+            $this->assertEquals($expectedtimestamps[$data['key']], $data['timestamp']);
+        }
+    }
+
+    /**
+     * Test get_timestamps with no keys specified, with and without optional hour/minute values.
+     */
+    public function test_get_timestamps_no_keys() {
+        $this->resetAfterTest(true);
+        $this->setAdminUser();
+
+        $time1 = new DateTime('2018-12-30 00:00:00');
+        $time2 = new DateTime('2019-03-27 23:59:00');
+
+        $dates = [
+            [
+                'year' => $time1->format('Y'),
+                'month' => $time1->format('m'),
+                'day' => $time1->format('d'),
+            ],
+            [
+                'year' => $time2->format('Y'),
+                'month' => (int) $time2->format('m'),
+                'day' => $time2->format('d'),
+                'hour' => $time2->format('H'),
+                'minute' => $time2->format('i'),
+            ],
+        ];
+
+        $expectedtimestamps = [
+            0 => $time1->getTimestamp(),
+            1 => $time2->getTimestamp(),
+        ];
+
+        $result = core_calendar_external::get_timestamps($dates);
+
+        $this->assertEquals(['timestamps'], array_keys($result));
+        $this->assertEquals(2, count($result['timestamps']));
+
+        foreach ($result['timestamps'] as $data) {
+            $this->assertEquals($expectedtimestamps[$data['key']], $data['timestamp']);
+        }
+    }
 }
diff --git a/calendar/upgrade.txt b/calendar/upgrade.txt
index 7bfbeb1a4e5..2f4273a7a98 100644
--- a/calendar/upgrade.txt
+++ b/calendar/upgrade.txt
@@ -9,6 +9,8 @@ information provided here is intended especially for developers.
   * calendar_cron()
   * calendar_get_mini()
   * calendar_get_upcoming()
+* Added core_calendar_external::get_timestamps(), which allows an array containing an arbitrary number of arrays of
+  date/time data to be converted and returned as timestamps, along with an optional key.
 
 === 3.6 ===
 * calendar_get_default_courses() function now has optional $userid parameter.
diff --git a/lib/db/services.php b/lib/db/services.php
index 167e4314dbc..32a55429516 100644
--- a/lib/db/services.php
+++ b/lib/db/services.php
@@ -261,6 +261,14 @@ $functions = array(
         'type' => 'read',
         'services' => array(MOODLE_OFFICIAL_MOBILE_SERVICE),
     ),
+    'core_calendar_get_timestamps' => [
+        'classname'     => 'core_calendar_external',
+        'methodname'    => 'get_timestamps',
+        'description'   => 'Fetch unix timestamps for given date times.',
+        'classpath' => 'calendar/externallib.php',
+        'type'          => 'read',
+        'ajax'          => true,
+    ],
     'core_cohort_add_cohort_members' => array(
         'classname' => 'core_cohort_external',
         'methodname' => 'add_cohort_members',