diff --git a/src/bar.js b/src/bar.js
index e27a85b2c..edc0feefe 100644
--- a/src/bar.js
+++ b/src/bar.js
@@ -591,6 +591,28 @@ export default class Bar {
     }
 
     compute_duration() {
+        // For hour-level precision, calculate duration directly in the configured unit
+        if (
+            ['Hour', 'Quarter Day', 'Half Day'].includes(
+                this.gantt.config.view_mode.name,
+            )
+        ) {
+            this.duration =
+                date_utils.diff(
+                    this.task._end,
+                    this.task._start,
+                    this.gantt.config.unit,
+                ) / this.gantt.config.step;
+
+            // For hour-level views, we don't need to worry about ignored dates/weekends
+            this.actual_duration_raw = this.duration;
+            this.ignored_duration_raw = 0;
+            this.task.actual_duration = this.duration;
+            this.task.ignored_duration = 0;
+            return;
+        }
+
+        // Original day-based calculation for day-level and above views
         let actual_duration_in_days = 0,
             duration_in_days = 0;
         for (
diff --git a/src/defaults.js b/src/defaults.js
index e63e8ef5c..48f93a2c9 100644
--- a/src/defaults.js
+++ b/src/defaults.js
@@ -130,19 +130,31 @@ const DEFAULT_OPTIONS = {
         if (ctx.task.description) ctx.set_subtitle(ctx.task.description);
         else ctx.set_subtitle('');
 
+        const is_hour_level = ['Hour', 'Quarter Day', 'Half Day'].includes(
+            ctx.chart.config.view_mode.name,
+        );
+        const date_format = is_hour_level ? 'MMM D HH:mm' : 'MMM D';
+
         const start_date = date_utils.format(
             ctx.task._start,
-            'MMM D',
+            date_format,
             ctx.chart.options.language,
         );
         const end_date = date_utils.format(
             date_utils.add(ctx.task._end, -1, 'second'),
-            'MMM D',
+            date_format,
             ctx.chart.options.language,
         );
 
+        const duration_unit = is_hour_level ? 'hours' : 'days';
+        const duration_value = is_hour_level
+            ? Math.round(
+                  date_utils.diff(ctx.task._end, ctx.task._start, 'hour') * 100,
+              ) / 100
+            : ctx.task.actual_duration;
+
         ctx.set_details(
-            `${start_date} - ${end_date} (${ctx.task.actual_duration} days${ctx.task.ignored_duration ? ' + ' + ctx.task.ignored_duration + ' excluded' : ''})<br/>Progress: ${Math.floor(ctx.task.progress * 100) / 100}%`,
+            `${start_date} - ${end_date} (${duration_value} ${duration_unit}${ctx.task.ignored_duration ? ' + ' + ctx.task.ignored_duration + ' excluded' : ''})<br/>Progress: ${Math.floor(ctx.task.progress * 100) / 100}%`,
         );
     },
     popup_on: 'click',
diff --git a/src/index.js b/src/index.js
index 054d3e2ce..c6fe930b8 100644
--- a/src/index.js
+++ b/src/index.js
@@ -165,10 +165,18 @@ export default class Gantt {
                 // cache index
                 task._index = i;
 
-                // if hours is not set, assume the last day is full day
-                // e.g: 2018-09-09 becomes 2018-09-09 23:59:59
+                // Only extend to full day if we're in day-level view modes and no time was specified
+                // For hour-level granularity, preserve the exact end time
                 const task_end_values = date_utils.get_date_values(task._end);
-                if (task_end_values.slice(3).every((d) => d === 0)) {
+                const is_hour_level_view = [
+                    'Hour',
+                    'Quarter Day',
+                    'Half Day',
+                ].includes(this.options.view_mode);
+                if (
+                    task_end_values.slice(3).every((d) => d === 0) &&
+                    !is_hour_level_view
+                ) {
                     task._end = date_utils.add(task._end, 24, 'hour');
                 }
 
@@ -323,7 +331,15 @@ export default class Gantt {
         }
         this.config.date_format =
             this.config.view_mode.date_format || this.options.date_format;
-        this.gantt_start.setHours(0, 0, 0, 0);
+
+        // Only reset hours for day-level and above views
+        if (
+            !['Hour', 'Quarter Day', 'Half Day'].includes(
+                this.config.view_mode.name,
+            )
+        ) {
+            this.gantt_start.setHours(0, 0, 0, 0);
+        }
     }
 
     setup_date_values() {