diff --git a/src/lib/server/services/heartbeatCall.js b/src/lib/server/services/heartbeatCall.js
index 652f568..5ff1b05 100644
--- a/src/lib/server/services/heartbeatCall.js
+++ b/src/lib/server/services/heartbeatCall.js
@@ -2,6 +2,7 @@
 import { UP, DOWN, DEGRADED, REALTIME, TIMEOUT, ERROR, MANUAL } from "../constants.js";
 import { GetMinuteStartNowTimestampUTC } from "../tool.js";
 import { GetLastHeartbeat } from "../controllers/controller.js";
+import { Cron } from "croner";
 
 class HeartbeatCall {
   monitor;
@@ -11,12 +12,37 @@ class HeartbeatCall {
   }
 
   async execute() {
-    let nowMinute = GetMinuteStartNowTimestampUTC();
+    let nowMinute = GetMinuteStartNowTimestampUTC(); // current time in seconds (minute start)
     let latestData = await GetLastHeartbeat(this.monitor.tag);
     if (!latestData) {
       return {};
     }
-    let latency = nowMinute - latestData.timestamp;
+
+    // Use croner to calculate expected heartbeat time
+    let expectedTime;
+    try {
+      const cronJob = Cron(this.monitor.cron);
+      const prevDate = cronJob.previousRun();
+      expectedTime = Math.floor(prevDate.getTime() / 1000); // seconds
+    } catch (err) {
+      return {
+        status: DOWN,
+        latency: 0,
+        type: ERROR,
+      };
+    }
+
+    // If heartbeat was received after or at expected time, it's UP
+    if (latestData.timestamp >= expectedTime) {
+      return {
+        status: UP,
+        latency: nowMinute - latestData.timestamp,
+        type: REALTIME,
+      };
+    }
+
+    // Calculate how late the expected heartbeat is
+    let latency = nowMinute - expectedTime;
     let downRemainingMinutes = Number(this.monitor.type_data.downRemainingMinutes);
     if (latency > downRemainingMinutes * 60) {
       return {
@@ -25,6 +51,7 @@ class HeartbeatCall {
         type: REALTIME,
       };
     }
+
     let degradedRemainingMinutes = Number(this.monitor.type_data.degradedRemainingMinutes);
     if (latency > degradedRemainingMinutes * 60) {
       return {
@@ -33,6 +60,7 @@ class HeartbeatCall {
         type: REALTIME,
       };
     }
+
     return {
       status: UP,
       latency: latency,