diff --git a/CHANGELOG.md b/CHANGELOG.md
index 45f42d47..a5140744 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -31,10 +31,12 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 * `Slider` and `DragValue` uses fewer decimals by default. See the full precision by hovering over the value.
 * `egui::App`: added `fn name(&self)` and `fn clear_color(&self)`.
 * Combo boxes has scroll bars when needed.
+* `ui.columns`: Columns now defaults to justified top-to-down layouts.
 
 ### Fixed 🐛
 
 * The background for `CentralPanel` will now cover unused space too.
+* `ui.columns`: Improve allocated size estimation.
 
 ### Deprecated
 * `RawInput::screen_size` - use `RawInput::screen_rect` instead.
diff --git a/egui/src/ui.rs b/egui/src/ui.rs
index 3968191a..9e8cb486 100644
--- a/egui/src/ui.rs
+++ b/egui/src/ui.rs
@@ -1044,24 +1044,26 @@ impl Ui {
                     pos,
                     pos2(pos.x + column_width, self.max_rect().right_bottom().y),
                 );
-                self.child_ui(child_rect, self.layout)
+                let mut column_ui =
+                    self.child_ui(child_rect, Layout::top_down_justified(Align::left()));
+                column_ui.set_width(column_width);
+                column_ui
             })
             .collect();
 
         let result = add_contents(&mut columns[..]);
 
-        let mut sum_width = total_spacing;
-        for column in &columns {
-            sum_width += column.min_rect().width();
-        }
-
+        let mut max_column_width = column_width;
         let mut max_height = 0.0;
-        for ui in columns {
-            let size = ui.min_size();
-            max_height = size.y.max(max_height);
+        for column in &columns {
+            max_column_width = max_column_width.max(column.min_rect().width());
+            max_height = column.min_size().y.max(max_height);
         }
 
-        let size = vec2(self.available_width().max(sum_width), max_height);
+        // Make sure we fit everything next frame:
+        let total_required_width = total_spacing + max_column_width * (num_columns as f32);
+
+        let size = vec2(self.available_width().max(total_required_width), max_height);
         self.allocate_space(size);
         result
     }