diff --git a/docs/ARCHITECTURE.md b/docs/ARCHITECTURE.md
index abb52f53..90e50d27 100644
--- a/docs/ARCHITECTURE.md
+++ b/docs/ARCHITECTURE.md
@@ -165,7 +165,7 @@ text, vectors, outlines, forms, page labels and document information remain PDF
   `CropService.LoadPreviewAsync`; nothing is decoded again while dragging. Programmatic changes (reset, a ratio, a
   new picture) ease in with tweens read against the clock, so a lost frame never leaves one half done; dragging and
   arrow-key nudges follow at once, and `PlayAnimations` (from `Motion.Enabled`) turns all of it off.
-- `Controls/AspectDial` is a small donut of the ratios (free, original, 1:1, 4:3, 3:2, 16:9): each slice a
+- `Controls/AspectDial` is a small donut of the ratios (free, original, 1:1, 5:4, 4:3, 3:2, 16:9): each slice a
   `RingSegment` button that answers only inside its wedge (`DonutGeometry.Wedge`, rounded by the softness), the hub
   swaps portrait and landscape. A with the pointer over the stage opens it around the pointer, as the donut opens,
   growing from its middle and kept inside the window; A without a pointer there (the keyboard) and its toolbar button
diff --git a/src/Filee.App/Controls/AspectDial.cs b/src/Filee.App/Controls/AspectDial.cs
index d4cd75e4..1d4819ad 100644
--- a/src/Filee.App/Controls/AspectDial.cs
+++ b/src/Filee.App/Controls/AspectDial.cs
@@ -1,5 +1,5 @@
-// The crop overlay's aspect dial: a small donut whose slices are the ratios (free, the picture's own, 1:1, 4:3, 3:2,
-// 16:9), each with a tiny outline of its shape, and a hub that swaps portrait and landscape. The slices are real
+// The crop overlay's aspect dial: a small donut whose slices are the ratios (free, the picture's own, 1:1, 5:4, 4:3,
+// 3:2, 16:9), each with a tiny outline of its shape, and a hub that swaps portrait and landscape. The slices are real
 // buttons (focus, keyboard, screen readers) that only answer inside their wedge. AspectGlyph is the dial in miniature
 // on the toolbar button that opens it.
 
@@ -220,8 +220,7 @@ public override void Render(DrawingContext context)
         DrawShape(context, ink, new Point(labelCenter.X, labelCenter.Y - 9));
 
         var typeface = new Typeface(GetValue(TextElement.FontFamilyProperty), FontStyle.Normal, FontWeight.SemiBold);
-        // As wide as the slice is a little outside its middle; a long word gets a smaller size before it would break.
-        var width = 2 * ((_inner + _outer) / 2 + 6) * Math.Sin(Math.Min(Math.PI / 2, DonutGeometry.Span(_count) / 2)) - 12;
+        var width = LabelWidth(_inner, _outer, _count);
         var direction = CultureInfo.CurrentUICulture.TextInfo.IsRightToLeft ? FlowDirection.RightToLeft : FlowDirection.LeftToRight;
         FormattedText Text(double size) => new(Label, CultureInfo.CurrentUICulture, direction, typeface, size, ink)
         {
@@ -233,10 +232,20 @@ public override void Render(DrawingContext context)
         var text = Text(12);
         var longest = Label.Split(' ').Max(word => new FormattedText(word, CultureInfo.CurrentUICulture, direction, typeface, 12, ink).Width);
         if (longest > width)
-            text = Text(Math.Max(9.5, 12 * width / longest));
+            text = Text(Math.Max(MinLabelSize, 12 * width / longest));
         context.DrawText(text, new Point(labelCenter.X - width / 2, labelCenter.Y + 2));
     }
 
+    /// <summary>
+    /// The smallest size a long one-word label shrinks to before it breaks. Ru's "Произвольные" needs 9.4 with seven
+    /// slices on a desktop and 8.7 on CI's runners, whose fonts differ, so there's room below that.
+    /// </summary>
+    internal const double MinLabelSize = 8;
+
+    /// <summary>As wide as the slice is a little outside its middle; a long word gets a smaller size before it would break.</summary>
+    internal static double LabelWidth(double inner, double outer, int count) =>
+        2 * ((inner + outer) / 2 + 6) * Math.Sin(Math.Min(Math.PI / 2, DonutGeometry.Span(count) / 2)) - 12;
+
     /// <summary>A small outline of the ratio over its name; free is a dashed square.</summary>
     private void DrawShape(DrawingContext context, IBrush? ink, Point center)
     {
@@ -258,7 +267,7 @@ private void DrawShape(DrawingContext context, IBrush? ink, Point center)
     }
 }
 
-/// <summary>The dial in miniature (the toolbar button): six slices, the one in use lit.</summary>
+/// <summary>The dial in miniature (the toolbar button): a slice per ratio, the one in use lit.</summary>
 public sealed class AspectGlyph : Control
 {
     public static readonly StyledProperty<int> SelectedIndexProperty =
diff --git a/src/Filee.App/Controls/CropMath.cs b/src/Filee.App/Controls/CropMath.cs
index 14f06064..b7bca2e4 100644
--- a/src/Filee.App/Controls/CropMath.cs
+++ b/src/Filee.App/Controls/CropMath.cs
@@ -10,13 +10,13 @@ public static class CropMath
     /// <summary>The aspect dial's choices, clockwise from the top.</summary>
     public static IReadOnlyList<string> AspectModes => Modes;
 
-    private static readonly string[] Modes = ["free", "original", "1:1", "4:3", "3:2", "16:9"];
+    private static readonly string[] Modes = ["free", "original", "1:1", "5:4", "4:3", "3:2", "16:9"];
 
     /// <summary>Where the mode sits on the dial, -1 for none.</summary>
     public static int AspectIndex(string mode) => Array.IndexOf(Modes, mode);
 
     /// <summary>A fixed ratio with a portrait and a landscape form (not free, the picture's own or square).</summary>
-    public static bool CanSwap(string mode) => mode is "4:3" or "3:2" or "16:9";
+    public static bool CanSwap(string mode) => mode is "5:4" or "4:3" or "3:2" or "16:9";
 
     /// <summary>Width / height of the mode, 0 for free. Portrait turns a swappable ratio around (4:3 → 3:4).</summary>
     public static double Ratio(string mode, bool portrait, int originalWidth, int originalHeight)
@@ -25,6 +25,7 @@ public static double Ratio(string mode, bool portrait, int originalWidth, int or
         {
             "original" => originalWidth > 0 && originalHeight > 0 ? (double)originalWidth / originalHeight : 0,
             "1:1" => 1.0,
+            "5:4" => 5.0 / 4.0, // upright: 4:5, Instagram's portrait size (#542)
             "4:3" => 4.0 / 3.0,
             "3:2" => 3.0 / 2.0,
             "16:9" => 16.0 / 9.0,
diff --git a/src/Filee.App/ViewModels/CropOverlayViewModel.cs b/src/Filee.App/ViewModels/CropOverlayViewModel.cs
index cd2f8d7e..2ab53d48 100644
--- a/src/Filee.App/ViewModels/CropOverlayViewModel.cs
+++ b/src/Filee.App/ViewModels/CropOverlayViewModel.cs
@@ -62,7 +62,7 @@ public sealed partial class CropOverlayViewModel : ObservableObject, IDisposable
     [NotifyPropertyChangedFor(nameof(IsAspectFree))]
     private string _selectedAspect = "free";
 
-    /// <summary>The fixed ratios (4:3, 3:2, 16:9) turned upright: 3:4, 2:3, 9:16.</summary>
+    /// <summary>The fixed ratios (5:4, 4:3, 3:2, 16:9) turned upright: 4:5, 3:4, 2:3, 9:16.</summary>
     [ObservableProperty]
     [NotifyPropertyChangedFor(nameof(AspectLabel))]
     [NotifyPropertyChangedFor(nameof(AspectToolTip))]
@@ -318,7 +318,7 @@ public void Cancel()
         CloseRequested?.Invoke();
     }
 
-    /// <summary>Locks the frame to a ratio of the dial ("free", "original", "1:1", "4:3", "3:2", "16:9") and closes the dial.</summary>
+    /// <summary>Locks the frame to a ratio of the dial ("free", "original", "1:1", "5:4", "4:3", "3:2", "16:9") and closes the dial.</summary>
     [RelayCommand]
     public void SetAspect(string mode)
     {
diff --git a/src/Filee.App/Views/CropOverlayWindow.axaml b/src/Filee.App/Views/CropOverlayWindow.axaml
index 22276d7d..4c8c86a7 100644
--- a/src/Filee.App/Views/CropOverlayWindow.axaml
+++ b/src/Filee.App/Views/CropOverlayWindow.axaml
@@ -407,6 +407,7 @@
         <c:RingSegment Mode="free" Content="{DynamicResource crop.aspect_free}" Command="{Binding SetAspectCommand}" CommandParameter="free" />
         <c:RingSegment Mode="original" Content="{DynamicResource crop.aspect_original}" Command="{Binding SetAspectCommand}" CommandParameter="original" />
         <c:RingSegment Mode="1:1" Command="{Binding SetAspectCommand}" CommandParameter="1:1" />
+        <c:RingSegment Mode="5:4" Command="{Binding SetAspectCommand}" CommandParameter="5:4" />
         <c:RingSegment Mode="4:3" Command="{Binding SetAspectCommand}" CommandParameter="4:3" />
         <c:RingSegment Mode="3:2" Command="{Binding SetAspectCommand}" CommandParameter="3:2" />
         <c:RingSegment Mode="16:9" Command="{Binding SetAspectCommand}" CommandParameter="16:9" />
diff --git a/tests/Filee.App.Tests/CropMathTests.cs b/tests/Filee.App.Tests/CropMathTests.cs
index 426d2ad0..7a021537 100644
--- a/tests/Filee.App.Tests/CropMathTests.cs
+++ b/tests/Filee.App.Tests/CropMathTests.cs
@@ -11,6 +11,8 @@ public class CropMathTests
     [Theory]
     [InlineData("free", false, 0.0)]
     [InlineData("1:1", true, 1.0)]
+    [InlineData("5:4", false, 5.0 / 4.0)]
+    [InlineData("5:4", true, 4.0 / 5.0)] // Instagram's portrait size
     [InlineData("4:3", false, 4.0 / 3.0)]
     [InlineData("4:3", true, 3.0 / 4.0)]
     [InlineData("3:2", true, 2.0 / 3.0)]
@@ -43,13 +45,14 @@ public void A_frame_as_wide_as_the_picture_never_counts_as_snapped()
     [Fact]
     public void Only_fixed_ratios_that_arent_square_swap()
     {
-        Assert.Equal(["4:3", "3:2", "16:9"], CropMath.AspectModes.Where(CropMath.CanSwap));
+        Assert.Equal(["5:4", "4:3", "3:2", "16:9"], CropMath.AspectModes.Where(CropMath.CanSwap));
+        Assert.Equal("4:5", CropMath.Numbers("5:4", portrait: true));
         Assert.Equal("9:16", CropMath.Numbers("16:9", portrait: true));
         Assert.Equal("16:9", CropMath.Numbers("16:9", portrait: false));
         Assert.Equal("1:1", CropMath.Numbers("1:1", portrait: true));
         Assert.Equal(0, CropMath.Ratio("original", false, 0, 0));
-        Assert.Equal(3, CropMath.AspectIndex("4:3"));
-        Assert.Equal(-1, CropMath.AspectIndex("5:4"));
+        Assert.Equal(4, CropMath.AspectIndex("4:3"));
+        Assert.Equal(-1, CropMath.AspectIndex("21:9"));
     }
 
     [Fact]
diff --git a/tests/Filee.App.Tests/CropOverlayTests.cs b/tests/Filee.App.Tests/CropOverlayTests.cs
index 52134aa6..834e61d6 100644
--- a/tests/Filee.App.Tests/CropOverlayTests.cs
+++ b/tests/Filee.App.Tests/CropOverlayTests.cs
@@ -288,6 +288,46 @@ public void Fixed_ratios_follow_the_pictures_orientation_and_swap()
         });
     }
 
+    [AvaloniaFact]
+    public void Every_language_fits_its_longest_one_word_ratio_name_on_a_slice_without_breaking_it()
+    {
+        var dial = new AspectDial();
+        var width = RingSegment.LabelWidth(dial.InnerRadius, dial.OuterRadius, CropMath.AspectModes.Count);
+        var i18n = Path.Combine(AppContext.BaseDirectory, "..", "..", "..", "..", "..", "src", "Filee.App", "Assets", "i18n");
+        foreach (var language in LocalizationService.Languages.Select(l => l.Code))
+        {
+            var strings = System.Text.Json.JsonSerializer.Deserialize<Dictionary<string, string>>(File.ReadAllText(Path.Combine(i18n, language + ".json")))!;
+            var typeface = new Avalonia.Media.Typeface(SoftPalette.FontFamilyFor(language), Avalonia.Media.FontStyle.Normal, Avalonia.Media.FontWeight.SemiBold);
+            foreach (var key in new[] { "crop.aspect_free", "crop.aspect_original" })
+            {
+                if (!strings.TryGetValue(key, out var label))
+                    continue;
+                var longest = label.Split(' ').Max(word => new Avalonia.Media.FormattedText(word, System.Globalization.CultureInfo.InvariantCulture,
+                    Avalonia.Media.FlowDirection.LeftToRight, typeface, 12, Avalonia.Media.Brushes.Black).Width);
+                Assert.True(12 * width / longest >= RingSegment.MinLabelSize, $"{language} {key} \"{label}\" needs {12 * width / longest:F2}");
+            }
+        }
+    }
+
+    [AvaloniaFact]
+    public void An_upright_picture_crops_at_instagrams_4_to_5_from_the_5_to_4_slice()
+    {
+        WithOverlay("en", false, ["tall.jpg"], (window, vm, _suffix) =>
+        {
+            Settle(window);
+            var slice = window.AspectDial.Segments.Single(s => s.Mode == "5:4");
+            slice.Command!.Execute(slice.CommandParameter);
+            Settle(window);
+            Assert.Equal("4:5", vm.AspectLabel);
+            Assert.Equal(0.8, window.CropCanvas.AspectRatio, 6);
+            var frame = window.CropCanvas.NormalizedCropRect;
+            Assert.Equal(0.8, frame.Width * 1000 / (frame.Height * 1600), 2);
+            vm.ToggleAspectDial();
+            Settle(window);
+            RenderTests.Save(window, "crop-dial-4-5.png");
+        });
+    }
+
     [AvaloniaFact]
     public void The_next_file_starts_free_and_full_in_view_and_canvas_alike()
     {