diff --git a/README.md b/README.md
index 7162fbc..32ee10b 100644
--- a/README.md
+++ b/README.md
@@ -35,6 +35,7 @@ These guides explain how to add the legacy self-contained 32-bit build to the os
 - Template and bookmark tools, including an optional global hotkey for bookmarks
 - Quick toggle bar under the menu bar: docked by default, or dragged out into a floating window for instant switches while editing
 - "Freeze preview" switch: pins the preview at the current editor time while the editor keeps running (the distance helper still follows the editor)
+- Y axis (time) scale from x0.5 to x4.0 in 0.1 steps, via the quick toggle bar's "Y Scale" slider or by holding **Ctrl** and scrolling inside the viewer window (only while the viewer is in the foreground; the X axis is unaffected)
 - Unified user settings and crash logs under a fixed `%LocalAppData%` path
 
 ## Requirements
diff --git a/osucatch-editor-realtimeviewer/DrawingHelper.cs b/osucatch-editor-realtimeviewer/DrawingHelper.cs
index 414b0ec..c24756d 100644
--- a/osucatch-editor-realtimeviewer/DrawingHelper.cs
+++ b/osucatch-editor-realtimeviewer/DrawingHelper.cs
@@ -163,6 +163,19 @@ public void LoadBeatmap(IBeatmap convertedBeatmap, int mods = 0)
             if (CustomComboColours.Count <= 0) CustomComboColours = DefaultCustomComboColours;
         }
 
+        /// <summary>
+        /// 由 approach time（ms）反推 AR：<see cref="LoadBeatmap"/> 里正向换算的逆运算
+        /// （AR &lt; 5 段 AT = 1800 - 120·AR，AR ≥ 5 段 AT = 1200 - 150·(AR-5)，两段在 AR=5 / AT=1200 处衔接）。
+        /// <para />用于把“当前 Y 轴缩放看到的纵向时间尺度”折算成大家熟悉的 AR：
+        /// 缩放到 <c>r</c> 时画面上 432 像素对应的时间是 <c>ApproachTime / r</c>，
+        /// 把它当成 AR 的 approach time 代进来即可。
+        /// </para>
+        /// </summary>
+        /// <param name="approachTime">approach time（ms）。</param>
+        /// <returns>等效 AR；超出 0~10 的值照实返回（不夹取）。</returns>
+        public static double ApproachRateFromApproachTime(double approachTime)
+            => (approachTime > 1200) ? (1800 - approachTime) / 120.0 : (1950 - approachTime) / 150.0;
+
         /// <summary>
         /// 将后台流水线构建好的数据原子地应用到当前绘制实例。
         /// 只替换装载期字段，不动 CurrentTime / NearbyHitObjects / Bookmarks 等运行时状态。
diff --git a/osucatch-editor-realtimeviewer/Form1.cs b/osucatch-editor-realtimeviewer/Form1.cs
index da96935..fa16063 100644
--- a/osucatch-editor-realtimeviewer/Form1.cs
+++ b/osucatch-editor-realtimeviewer/Form1.cs
@@ -87,6 +87,19 @@ public partial class Form1 : Form
         /// <summary>滑块刻度间隔（同样以 0.1 为单位）：每 0.5 倍画一根刻度线。</summary>
         private const int VerticalScaleTickTenths = 5;
 
+        /// <summary>一格滚轮（Ctrl + 滚轮）调整多少：1 = 0.1，与滑块步进一致。</summary>
+        private const int VerticalScaleTenthsPerWheelNotch = 1;
+
+        /// <summary>Y 缩放功能区里“当前缩放相当于多少 AR”那一段文字的标识。</summary>
+        private const string VerticalScaleArTextKey = "VerticalScaleAR";
+
+        /// <summary>
+        /// 当前 Y 轴缩放（以 0.1 为单位）。与滑块位置、<see cref="DrawingHelper.VerticalScale"/>
+        /// 一起由 <see cref="ApplyVerticalScale"/> 统一维护，Ctrl + 滚轮也走同一条路径，
+        /// 这样“滚轮改完滑块跟着动”天然成立（浮点倍率不适合拿来累加，故另存一份整数）。
+        /// </summary>
+        private int verticalScaleTenths = VerticalScaleDefaultTenths;
+
         /// <summary>快捷开关条上的下拉框 / 滑块所用的值标识。</summary>
         private const string FreezeValueKey = FreezePreviewTimeKey;
 
@@ -345,6 +358,14 @@ private void Form1_Load(object sender, EventArgs e)
             ApplyBarLineMode(BarLineSettings.CurrentMode, persist: false);
             // 垂直缩放不持久化：每次启动都把滑块与画面恢复成默认的 x1.0
             ApplyVerticalScale(VerticalScaleDefaultTenths);
+            // Ctrl + 滚轮缩放 Y 轴：滚轮消息发给“拥有键盘焦点的窗口”（焦点可能在画布上），
+            // 用消息过滤器在消息分发前拦下，不依赖 WinForms 的滚轮冒泡行为
+            wheelFilter = new VerticalScaleWheelFilter(this);
+            Application.AddMessageFilter(wheelFilter);
+            FormClosed += (sender, e) =>
+            {
+                if (wheelFilter != null) Application.RemoveMessageFilter(wheelFilter);
+            };
             quickToggleDocking?.ApplyStartupState(
                 app.Default.QuickToggle_Visible,
                 app.Default.QuickToggle_Floating,
@@ -635,6 +656,8 @@ private void RequestDraw(int? editorTime, string? title, string statusText)
                     if (IsDisposed || Disposing) return;
                     if (title != null && this.Text != title) this.Text = title;
                     if (StateToolStripStatusLabel.Text != statusText) StateToolStripStatusLabel.Text = statusText;
+                    // 后台重建刚提交的话 ApproachTime 可能已变（开/关 EZ、HR 或换谱面）：顺带刷新“等效 AR”
+                    RefreshVerticalScaleArText();
                     this.Canvas.Canvas_Paint(null, null);
                 }));
                 Log.ConsoleLog("Draw a frame successful.", Log.LogType.Drawing, Log.LogLevel.Debug);
@@ -1592,6 +1615,11 @@ private void CreateQuickToggles()
                 VerticalScaleDefaultTenths,
                 VerticalScaleTickTenths);
             scaleGroup.AddLabel(VerticalScaleValueKey + "_Text", VerticalScaleStatusText());
+            // 当前缩放相当于多少 AR：紧跟在比例后面（开 EZ / HR 时按 mod 后的实际 AR 折算）
+            scaleGroup.AddLabel(VerticalScaleArTextKey, VerticalScaleArText());
+            // 条上只放得下“x1.0”“AR 9.3”，Ctrl+滚轮与折算口径写进悬停提示
+            quickToggleBar.SetGroupLabelToolTip(VerticalScaleGroupKey, VerticalScaleValueKey + "_Text", VerticalScaleHintText());
+            quickToggleBar.SetGroupLabelToolTip(VerticalScaleGroupKey, VerticalScaleArTextKey, VerticalScaleArHintText());
 
             ApplyQuickToggleIcons();
         }
@@ -1769,10 +1797,13 @@ private static string LabelToggleToolTip(QuickLabelMode mode)
         private void ApplyVerticalScale(int tenths)
         {
             int clamped = Math.Clamp(tenths, VerticalScaleMinTenths, VerticalScaleMaxTenths);
+            verticalScaleTenths = clamped;
             drawingHelper.VerticalScale = clamped / 10f;
 
             quickToggleBar?.SetGroupSliderValue(VerticalScaleGroupKey, VerticalScaleValueKey, clamped);
             quickToggleBar?.SetGroupLabelText(VerticalScaleGroupKey, VerticalScaleValueKey + "_Text", VerticalScaleStatusText());
+            // 比例一变，等效 AR 跟着变（同一帧内一起刷新，两个数字不会出现一帧的错位）
+            RefreshVerticalScaleArText();
         }
 
         /// <summary>
@@ -1781,6 +1812,144 @@ private void ApplyVerticalScale(int tenths)
         /// </summary>
         private static string VerticalScaleStatusText() => "x" + drawingHelper.VerticalScale.ToString("0.0");
 
+        /// <summary>
+        /// 当前 Y 轴缩放相当于多少 AR（形如 <c>AR 9.3</c>）。
+        /// <para />折算口径：画面上 432 像素对应的时间就是 <see cref="DrawingHelper.TimePerPixels"/> 的来历
+        /// （<c>TimePerPixels = ApproachTime / 432</c>）。缩放 <c>r</c> 倍后同样 432 像素对应
+        /// <c>ApproachTime / r</c> 毫秒，把这个时间当成 AR 的 approach time 反推，就得到等效 AR：
+        /// 放大（x&gt;1）看到的时间尺度更短 → 等效 AR 更高，压扁则更低。
+        /// </para>
+        /// <para /><see cref="DrawingHelper.ApproachTime"/> 取自绘制状态，而它是由
+        /// <c>convertedBeatmap.Difficulty.ApproachRate</c> 算出来的——EZ / HR 属于
+        /// <c>IApplicableToDifficulty</c>，在换谱面的转换阶段就已经作用到难度值上，
+        /// 所以开 mod 后这里显示的自然是按 mod 后实际 AR 折算的结果。
+        /// </para>
+        /// <para />等效值可能超出 0~10（放大到 4x 会高于 AR10，压扁到 0.5x 可能低于 AR0），一律照实显示。
+        /// </para>
+        /// </summary>
+        private static string VerticalScaleArText()
+        {
+            int approachTime = drawingHelper.ApproachTime;
+            float scale = drawingHelper.VerticalScale;
+            // 还没读到谱面（ApproachTime 尚未装载）时给个占位符，避免显示 AR NaN / 负无穷
+            if (approachTime <= 0 || !(scale > 0)) return "AR -";
+
+            double ar = DrawingHelper.ApproachRateFromApproachTime(approachTime / (double)scale);
+            return "AR" + ar.ToString("0.0");
+        }
+
+        /// <summary>上次刷新“等效 AR”用的输入，避免每帧都重新格式化字符串。</summary>
+        private int arTextCachedApproachTime = -1;
+        private float arTextCachedScale = -1f;
+
+        /// <summary>
+        /// 刷新“等效 AR”文字（只在 UI 线程调用）。
+        /// <para />两个触发点：比例变化时由 <see cref="ApplyVerticalScale"/> 立即刷新；
+        /// 后台重建提交后 <see cref="DrawingHelper.ApproachTime"/> 会变（开 / 关 EZ、HR 或换谱面都走这条路，
+        /// 而提交发生在后台线程），由每帧绘制前的 <see cref="RequestDraw"/> 顺带补上。
+        /// </para>
+        /// </summary>
+        private void RefreshVerticalScaleArText()
+        {
+            int approachTime = drawingHelper.ApproachTime;
+            float scale = drawingHelper.VerticalScale;
+            if (approachTime == arTextCachedApproachTime && scale == arTextCachedScale) return;
+
+            arTextCachedApproachTime = approachTime;
+            arTextCachedScale = scale;
+            quickToggleBar?.SetGroupLabelText(VerticalScaleGroupKey, VerticalScaleArTextKey, VerticalScaleArText());
+        }
+
+        /// <summary>
+        /// Y 缩放比例文字的悬停提示：条上只显示“x1.0”，这里把 Ctrl + 滚轮的快捷操作一并说明。
+        /// </summary>
+        private static string VerticalScaleHintText()
+        {
+            bool chinese = Thread.CurrentThread.CurrentUICulture.TwoLetterISOLanguageName == "zh";
+            return chinese
+                ? "Y 轴缩放比例（在 viewer 窗口内按住 Ctrl 滚滚轮也能调，每格 0.1）"
+                : "Y axis scale (hold Ctrl and scroll inside the viewer window; 0.1 per notch)";
+        }
+
+        /// <summary>“等效 AR”文字的悬停提示：说明它是按当前缩放折算出来的，并点明 mod 口径。</summary>
+        private static string VerticalScaleArHintText()
+        {
+            bool chinese = Thread.CurrentThread.CurrentUICulture.TwoLetterISOLanguageName == "zh";
+            return chinese
+                ? "按当前 Y 缩放折算的等效 AR：把画面上“432 像素对应的时间”当成 AR 的 approach time 反推；"
+                  + "开 EZ / HR 时按 mod 后的实际 AR 计算（缩放只改显示比例，不改谱面数据）"
+                : "Effective AR implied by the current Y scale (the 432-pixel approach distance is re-expressed as an AR); "
+                  + "uses the modded AR when EZ / HR is on (the scale only changes the view, not the beatmap)";
+        }
+
+        #region Y 轴缩放：Ctrl + 滚轮
+
+        /// <summary>滚轮消息（WM_MOUSEWHEEL）；wParam 高 16 位是带符号的滚动量。</summary>
+        private const int WM_MOUSEWHEEL = 0x020A;
+
+        /// <summary>Ctrl + 滚轮的消息过滤器实例（随窗体关闭一并注销）。</summary>
+        private VerticalScaleWheelFilter? wheelFilter;
+
+        /// <summary>
+        /// Ctrl + 滚轮调整 Y 轴缩放的消息过滤器。
+        /// <para /><b>为什么用消息过滤器而不是重写 <c>OnMouseWheel</c></b>：滚轮消息由系统发给
+        /// “当前拥有键盘焦点的窗口”。焦点可能落在画布上（<see cref="Canvas"/> 是 GLControl，
+        /// 有自己独立的窗口句柄），也可能落在主窗口本身；过滤器在消息进入控件之前就能看到，
+        /// 因此不必依赖“未处理的滚轮消息会被 WinForms 冒泡给父控件”这个实现细节。
+        /// </para>
+        /// <para />回调里的三道闸（前台、光标在窗口内、按住 Ctrl）都在 <see cref="TryZoomVerticalScaleByWheel"/>。
+        /// </para>
+        /// </summary>
+        private sealed class VerticalScaleWheelFilter : IMessageFilter
+        {
+            private readonly Form1 owner;
+
+            internal VerticalScaleWheelFilter(Form1 owner) => this.owner = owner;
+
+            public bool PreFilterMessage(ref Message m)
+            {
+                if (m.Msg != WM_MOUSEWHEEL) return false;
+
+                int delta = (short)((m.WParam.ToInt64() >> 16) & 0xFFFF);
+                return owner.TryZoomVerticalScaleByWheel(delta);
+            }
+        }
+
+        /// <summary>
+        /// 处理一次滚轮消息：只有“viewer 在前台 + 光标在 viewer 窗口内 + 按住 Ctrl”时才调整 Y 轴缩放。
+        /// <para />向上滚 = 放大（把时间轴拉长），一格 0.1，与滑块步进一致；缩放基准仍是判定线，
+        /// 与拖滑块完全等价（滚轮只是另一个入口）。
+        /// </para>
+        /// </summary>
+        /// <returns>true 表示这条滚轮消息已被消费，不再交给画布 / 快捷开关栏等控件。</returns>
+        private bool TryZoomVerticalScaleByWheel(int wheelDelta)
+        {
+            // 正在关闭时不再动控件（消息过滤器要等 FormClosed 才注销，期间可能还有滚轮消息在途）
+            if (IsDisposed || Disposing) return false;
+
+            // ① 本窗口必须在前台：焦点在窗口内的任意子控件上才算。
+            //    “viewer 不在前台”包含两类情况，这里一并挡掉：
+            //    - 焦点在别的程序（或本程序的浮窗 / 设置窗口）上；
+            //    - Windows 的“悬停时滚动非活动窗口”把滚轮直接送到悬停窗口，但焦点并不在我们的窗口上。
+            if (!ContainsFocus) return false;
+
+            // ② 光标必须落在 viewer 窗口内（Ctrl+滚轮甩到窗口外时不该改缩放）
+            if (!Bounds.Contains(Cursor.Position)) return false;
+
+            // ③ 必须按住 Ctrl：没按 Ctrl 时把滚轮让给其它控件（菜单栏溢出滚动、下拉框等）
+            if ((ModifierKeys & Keys.Control) != Keys.Control) return false;
+
+            int notches = wheelDelta / SystemInformation.MouseWheelScrollDelta;
+            // 高精度滚轮 / 触摸板可能只报小于一格（120）的增量：按方向算作一格，避免完全没反应
+            if (notches == 0) notches = Math.Sign(wheelDelta);
+            if (notches == 0) return false;
+
+            ApplyVerticalScale(verticalScaleTenths + notches * VerticalScaleTenthsPerWheelNotch);
+            return true;
+        }
+
+        #endregion
+
 
 
 
@@ -2088,6 +2257,10 @@ private void ApplyQuickToggleLanguage()
 
             quickToggleBar.SetGroupLabelText(BarLineGroupKey, BarLineValueKey + "_Text", BarLineStatusText());
             quickToggleBar.SetGroupLabelText(VerticalScaleGroupKey, VerticalScaleValueKey + "_Text", VerticalScaleStatusText());
+            // 等效 AR 的文字本身与语言无关（“AR 9.3”），但提示要跟着语言走
+            RefreshVerticalScaleArText();
+            quickToggleBar.SetGroupLabelToolTip(VerticalScaleGroupKey, VerticalScaleValueKey + "_Text", VerticalScaleHintText());
+            quickToggleBar.SetGroupLabelToolTip(VerticalScaleGroupKey, VerticalScaleArTextKey, VerticalScaleArHintText());
         }
 
         /// <summary>
diff --git a/osucatch-editor-realtimeviewer/QuickToggleBar.cs b/osucatch-editor-realtimeviewer/QuickToggleBar.cs
index c55f70d..3cd43c2 100644
--- a/osucatch-editor-realtimeviewer/QuickToggleBar.cs
+++ b/osucatch-editor-realtimeviewer/QuickToggleBar.cs
@@ -729,6 +729,15 @@ internal void SetGroupLabelText(string groupKey, string labelKey, string text)
             if (groups.TryGetValue(groupKey, out QuickToggleGroup? group)) group.SetLabelText(labelKey, text);
         }
 
+        /// <summary>
+        /// 设置功能区里一段只读文字的悬停提示（语言切换等场景调用）。
+        /// 条上的文字通常很短（如“x1.0”），快捷键之类的补充说明放在这里。
+        /// </summary>
+        internal void SetGroupLabelToolTip(string groupKey, string labelKey, string toolTip)
+        {
+            if (groups.TryGetValue(groupKey, out QuickToggleGroup? group)) group.SetLabelToolTip(labelKey, toolTip);
+        }
+
         #endregion
 
         #region 停靠 / 浮动
@@ -1120,6 +1129,16 @@ internal void SetLabelText(string labelKey, string text)
                 if (labels.TryGetValue(labelKey, out ToolStripLabel? item)) item.Text = text;
             }
 
+            /// <summary>设置功能区里一段只读文字的悬停提示。</summary>
+            internal void SetLabelToolTip(string labelKey, string toolTip)
+            {
+                if (!labels.TryGetValue(labelKey, out ToolStripLabel? item)) return;
+
+                // AutoToolTip = true 会用 Text 覆盖 ToolTipText，这里必须关掉才显示得出提示
+                item.AutoToolTip = false;
+                item.ToolTipText = toolTip;
+            }
+
             /// <summary>功能区里的只读文字项，键为文字标识。</summary>
             private readonly Dictionary<string, ToolStripLabel> labels = new(StringComparer.Ordinal);