diff --git a/crates/gpu/src/walk.rs b/crates/gpu/src/walk.rs
index 81f30d4f..b6e78870 100644
--- a/crates/gpu/src/walk.rs
+++ b/crates/gpu/src/walk.rs
@@ -26,9 +26,7 @@ pub(crate) fn render<'g>(e: &mut Enc<'g>, r: &Renderer, comp_id: ItemId, t: Tick
         return None;
     }
     let ctx = r.eval_ctx(comp_id, t)?;
-    let s = r.opts.scale;
-    let w = ((ctx.comp.width as f64 * s).round() as u32).max(1);
-    let h = ((ctx.comp.height as f64 * s).round() as u32).max(1);
+    let (w, h) = effectcraft_render::frame_size(ctx.comp.width, ctx.comp.height, r.opts.scale);
     if r.depth() > 16 || !e.g.fits(w, h) {
         return None;
     }
diff --git a/crates/render/src/lib.rs b/crates/render/src/lib.rs
index de4023bf..ebe0a018 100644
--- a/crates/render/src/lib.rs
+++ b/crates/render/src/lib.rs
@@ -981,8 +981,7 @@ impl<'a> Renderer<'a> {
     pub fn comp_frame_cpu(&self, comp_id: ItemId, t: Tick) -> Image {
         let Some(comp) = self.project.comp(comp_id) else { return Image::new(1, 1) };
         let s = self.opts.scale;
-        let w = ((comp.width as f64 * s).round() as u32).max(1);
-        let h = ((comp.height as f64 * s).round() as u32).max(1);
+        let (w, h) = frame_size(comp.width, comp.height, s);
         // Region of interest on a comp with 3D layers: render the frame and crop it. A region
         // reaching past the comp frame (the Extended Viewer) renders Classic 3D natively — the
         // planes project through the offset camera — and Advanced 3D as the frame, padded.
@@ -2389,6 +2388,12 @@ pub fn extended_region(w: u32, h: u32, visible: [f64; 4], margin: f64) -> Option
     Some([x0, y0, x1 - x0, y1 - y0])
 }
 
+/// The size of a `width` x `height` comp frame rendered at `scale` (both compositors, and the
+/// frame size Composition Settings shows for a Resolution).
+pub fn frame_size(width: u32, height: u32, scale: f64) -> (u32, u32) {
+    (((width as f64 * scale).round() as u32).max(1), ((height as f64 * scale).round() as u32).max(1))
+}
+
 pub fn render_frame(project: &Project, comp: ItemId, t: Tick, scale: f64) -> Image {
     Renderer::new(project, &NoFootage, RenderOpts { scale, ..Default::default() }).comp_frame(comp, t)
 }
diff --git a/crates/ui-egui/src/i18n/ui.rs b/crates/ui-egui/src/i18n/ui.rs
index fab6c2e0..d803e2e7 100644
--- a/crates/ui-egui/src/i18n/ui.rs
+++ b/crates/ui-egui/src/i18n/ui.rs
@@ -298,6 +298,7 @@ const JAPANESE: &[(&str, &str)] = &[
     ("Frame Aspect Ratio: {}", "フレームアスペクト比：{}"),
     ("Frame Blending: {}", "フレームブレンド：{}"),
     ("Frame Rate:", "フレームレート:"),
+    ("Resolution:", "解像度:"),
     ("Frame Render Time  {}ms", "フレームのレンダリング時間  {}ms"),
     ("Frame Target:", "フレームターゲット:"),
     ("Freeze", "フリーズ"),
@@ -1033,6 +1034,7 @@ const SIMPLIFIED_CHINESE: &[(&str, &str)] = &[
     ("Frame Aspect Ratio: {}", "帧长宽比：{}"),
     ("Frame Blending: {}", "帧混合：{}"),
     ("Frame Rate:", "帧速率："),
+    ("Resolution:", "分辨率："),
     ("Frame Render Time  {}ms", "帧渲染时间  {} 毫秒"),
     ("Frame Target:", "帧目标："),
     ("Freeze", "冻结"),
@@ -1773,6 +1775,7 @@ const TRADITIONAL_CHINESE: &[(&str, &str)] = &[
     ("Frame Aspect Ratio: {}", "影格長寬比：{}"),
     ("Frame Blending: {}", "影格混合：{}"),
     ("Frame Rate:", "影格速率："),
+    ("Resolution:", "解析度："),
     ("Frame Render Time  {}ms", "影格算圖時間  {} 毫秒"),
     ("Frame Target:", "幀目標："),
     ("Freeze", "凍結"),
@@ -2467,6 +2470,7 @@ const UKRAINIAN: &[(&str, &str)] = &[
     ("Frame Aspect Ratio: {}", "Пропорції кадру: {}"),
     ("Frame Blending: {}", "Змішування кадрів: {}"),
     ("Frame Rate:", "Частота кадрів:"),
+    ("Resolution:", "Роздільність:"),
     ("Frame Render Time  {}ms", "Час рендерингу кадру  {} мс"),
     ("Frame Target:", "Цільовий фрейм:"),
     ("Freeze", "Заморозити"),
@@ -3027,6 +3031,7 @@ const PORTUGUESE: &[(&str, &str)] = &[
     ("Frame Aspect Ratio: {}", "Proporção do quadro: {}"),
     ("Frame Blending: {}", "Mesclagem de quadros: {}"),
     ("Frame Rate:", "Taxa de quadros:"),
+    ("Resolution:", "Resolução:"),
     ("Frame Render Time  {}ms", "Tempo de renderização do quadro  {}ms"),
     ("Frame Target:", "Destino do quadro:"),
     ("Grab bag", "Lista"),
@@ -3485,6 +3490,7 @@ const CZECH: &[(&str, &str)] = &[
     ("Frame Aspect Ratio: {}", "Poměr stran snímku: {}"),
     ("Frame Blending: {}", "Prolnutí snímků: {}"),
     ("Frame Rate:", "Snímková frekvence:"),
+    ("Resolution:", "Rozlišení:"),
     ("Frame Render Time  {}ms", "Čas vykreslení snímku  {}ms"),
     ("Frame Target:", "Cílový rámec:"),
     ("Freeze", "Zmrazit"),
@@ -4048,6 +4054,7 @@ const SPANISH: &[(&str, &str)] = &[
     ("Frame Aspect Ratio: {}", "Relación de aspecto del fotograma: {}"),
     ("Frame Blending: {}", "Fusión de fotogramas: {}"),
     ("Frame Rate:", "Velocidad de fotogramas:"),
+    ("Resolution:", "Resolución:"),
     ("Frame Render Time  {}ms", "Tiempo de procesamiento del fotograma  {}ms"),
     ("Frame Target:", "Marco de destino:"),
     ("Freeze", "Congelar"),
diff --git a/crates/ui-egui/src/panels/comp_settings.rs b/crates/ui-egui/src/panels/comp_settings.rs
index 2cd19df5..7e676bcc 100644
--- a/crates/ui-egui/src/panels/comp_settings.rs
+++ b/crates/ui-egui/src/panels/comp_settings.rs
@@ -5,6 +5,7 @@
 use crate::i18n::{tr, tr_args};
 use crate::icons::Icon;
 use effectcraft_engine::prefs::CompPreset;
+use effectcraft_engine::project::Resolution;
 use effectcraft_engine::time::{FrameRate, format_timecode_frames, parse_timecode};
 use egui::{Color32, vec2};
 use serde_json::json;
@@ -94,6 +95,9 @@ pub struct CompDraft {
     pub preserve_frame_rate: bool,
     pub preserve_resolution: bool,
     pub advanced_3d: bool,
+    /// The comp's Resolution (the Composition panel's popup): saved with the project but no undo
+    /// step, so OK sets it apart from `comp.new` / `comp.settings`.
+    pub resolution: Resolution,
     pub tab: Tab,
     /// Timecode text being edited (start, duration).
     pub start_tc: Option<String>,
@@ -122,6 +126,7 @@ impl Default for CompDraft {
             preserve_frame_rate: false,
             preserve_resolution: false,
             advanced_3d: false,
+            resolution: Resolution::Auto,
             tab: Tab::Basic,
             start_tc: None,
             dur_tc: None,
@@ -376,9 +381,30 @@ pub fn show(
                     }
                 });
                 ui.end_row();
-                ui.label("");
-                let mb = d.width as f64 * d.height as f64 * 4.0 / (1024.0 * 1024.0);
-                ui.label(egui::RichText::new(tr_args("{} x {}, {}MB per 8bpc frame", &[&d.width, &d.height, &format!("{mb:.1}")])).color(Color32::GRAY));
+                // As in After Effects, the Resolution menu (the Composition panel's popup) with
+                // the frame it renders beside it.
+                ui.label(tr("Resolution:"));
+                ui.horizontal(|ui| {
+                    let r = egui::ComboBox::from_id_salt("comp-resolution").width(90.0).selected_text(tr(d.resolution.label())).show_ui(ui, |ui| {
+                        for res in Resolution::ALL {
+                            ui.selectable_value(&mut d.resolution, res, tr(res.label()));
+                        }
+                        let custom = matches!(d.resolution, Resolution::Custom(_));
+                        if ui.selectable_label(custom, tr("Custom")).clicked() && !custom {
+                            d.resolution = Resolution::Custom(5);
+                        }
+                    });
+                    auto.add("dialog.comp.resolution", r.response.rect, "Resolution");
+                    if let Resolution::Custom(n) = d.resolution {
+                        let mut n = n;
+                        let r = ui.add(crate::widgets::drag_value(egui::DragValue::new(&mut n).range(2..=40)));
+                        auto.add("dialog.comp.resolutionFactor", r.rect, "Custom Resolution");
+                        d.resolution = Resolution::Custom(n);
+                    }
+                    let (w, h) = frame_at(d.width, d.height, d.resolution);
+                    let mb = w as f64 * h as f64 * 4.0 / (1024.0 * 1024.0);
+                    ui.label(egui::RichText::new(tr_args("{} x {}, {}MB per 8bpc frame", &[&w, &h, &format!("{mb:.1}")])).color(Color32::GRAY));
+                });
                 ui.end_row();
                 ui.label(tr("Start Timecode:"));
                 let r = ui.horizontal(|ui| timecode_field(ui, &mut d.start_tc, &mut d.start, rate, i64::MIN / 4)).inner;
@@ -486,10 +512,26 @@ pub fn params(d: &CompDraft) -> serde_json::Value {
     })
 }
 
+/// The frame size the comp renders at `res` (Auto follows the magnification, so the dialog shows
+/// the full frame for it).
+pub fn frame_at(w: u32, h: u32, res: Resolution) -> (u32, u32) {
+    effectcraft_render::frame_size(w, h, 1.0 / f64::from(res.factor().unwrap_or(1).max(1)))
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
 
+    #[test]
+    fn frame_size_follows_the_resolution() {
+        // The renderer's size, which rounds: 1081 / 3 = 360.33 and 1920 / 7 = 274.3.
+        assert_eq!(frame_at(1920, 1081, Resolution::Third), (640, 360));
+        assert_eq!(frame_at(1920, 1080, Resolution::Custom(7)), (274, 154));
+        assert_eq!(frame_at(1920, 1081, Resolution::Half), (960, 541));
+        assert_eq!(frame_at(1920, 1080, Resolution::Full), (1920, 1080));
+        assert_eq!(frame_at(1920, 1080, Resolution::Auto), (1920, 1080));
+    }
+
     #[test]
     fn aspect_labels_match_ae() {
         assert_eq!(aspect_label(1920.0, 1080.0), "16:9 (1.78)");
diff --git a/crates/ui-egui/src/panels/dialogs.rs b/crates/ui-egui/src/panels/dialogs.rs
index f4413d14..07b257e2 100644
--- a/crates/ui-egui/src/panels/dialogs.rs
+++ b/crates/ui-egui/src/panels/dialogs.rs
@@ -103,6 +103,7 @@ pub fn open_comp_settings_for(app: &mut EffectcraftApp, cid: ItemId) -> Result<(
         preserve_frame_rate: c.preserve_frame_rate,
         preserve_resolution: c.preserve_resolution,
         advanced_3d: c.renderer == effectcraft_engine::project::Renderer::Advanced3D,
+        resolution: c.resolution,
         ..Default::default()
     };
     app.dialog_state.editing_existing = true;
@@ -410,6 +411,11 @@ fn comp_settings(app: &mut EffectcraftApp, ctx: &egui::Context, t: &Tokens, exis
                 m.insert("comp".into(), json!(cid.0));
             }
             let r = if existing { app.session.execute("comp.settings", params) } else { app.session.execute("comp.new", params) };
+            let cid = if existing { app.dialog_state.editing_comp.map(|c| c.0) } else { r.as_ref().ok().and_then(|v| v["comp"].as_u64()) };
+            let r = match cid {
+                Some(cid) if r.is_ok() => set_resolution(app, cid, app.dialog_state.comp.resolution).and(r),
+                _ => r,
+            };
             if !existing && r.is_ok() {
                 app.dialog_state.last_new_comp = Some(app.dialog_state.comp.clone());
             }
@@ -422,6 +428,15 @@ fn comp_settings(app: &mut EffectcraftApp, ctx: &egui::Context, t: &Tokens, exis
     }
 }
 
+/// The Resolution chosen in Composition Settings, set as the Composition panel's popup sets it:
+/// saved with the project but no undo step, so it stays out of `comp.new` / `comp.settings`.
+fn set_resolution(app: &mut EffectcraftApp, cid: u64, r: effectcraft_engine::project::Resolution) -> effectcraft_engine::Result<Value> {
+    match r.factor() {
+        None => app.session.execute("view.res.auto", json!({"comp": cid})),
+        Some(n) => app.session.execute("view.res.custom", json!({"comp": cid, "factor": n})),
+    }
+}
+
 /// One frame of the open dialog with `key` pressed.
 #[cfg(test)]
 pub(crate) fn press_key(app: &mut EffectcraftApp, ctx: &egui::Context, key: egui::Key, modifiers: egui::Modifiers) {
@@ -829,6 +844,59 @@ mod tests {
         assert_eq!(selected(&ctx), Some(0..app.dialog_state.solid_name.chars().count()));
     }
 
+    /// One frame of Composition Settings (or New Composition) with Enter pressed: OK.
+    fn press_ok(app: &mut EffectcraftApp, ctx: &egui::Context, existing: bool) {
+        let t = app.tokens;
+        let mut out = ctx.run_ui(Default::default(), |ui| {
+            app.auto.begin_frame();
+            ui.input_mut(|i| {
+                i.events.push(egui::Event::Key { key: egui::Key::Enter, physical_key: None, pressed: true, repeat: false, modifiers: Default::default() })
+            });
+            comp_settings(app, ui.ctx(), &t, existing);
+        });
+        out.textures_delta.clear();
+        assert!(app.dialog.is_none(), "OK closed the dialog");
+    }
+
+    /// The Resolution menu sets the comp's Resolution on OK. As from the Composition panel's popup
+    /// it is no undo step: the settings are one step, and undoing them keeps the Resolution.
+    #[test]
+    fn composition_settings_resolution_applies_on_ok_outside_the_undo_history() {
+        use effectcraft_engine::project::Resolution;
+        let (mut app, ctx) = app();
+        let cid = app.session.active_comp_id().unwrap();
+        app.session.execute("view.res.third", json!({})).unwrap();
+        open_comp_settings(&mut app).unwrap();
+        assert_eq!(app.dialog_state.comp.resolution, Resolution::Third, "the dialog opens on the comp's Resolution");
+        frame(&mut app, &ctx);
+        assert!(app.auto.find("dialog.comp.resolution").is_some());
+        let steps = app.session.history.undo.len();
+        (app.dialog_state.comp.resolution, app.dialog_state.comp.width) = (Resolution::Half, 700);
+        app.dialog_state.comp.lock_aspect = false;
+        press_ok(&mut app, &ctx, true);
+        let c = app.session.project.comp(cid).unwrap();
+        assert_eq!((c.width, c.resolution), (700, Resolution::Half));
+        assert_eq!(app.session.history.undo.len(), steps + 1, "Composition Settings is one undo step");
+        app.session.execute("edit.undo", json!({})).unwrap();
+        let c = app.session.project.comp(cid).unwrap();
+        assert_eq!((c.width, c.resolution), (640, Resolution::Half), "undo keeps the Resolution");
+        // Only the Resolution changed: still set, and no extra step.
+        open_comp_settings(&mut app).unwrap();
+        app.dialog_state.comp.resolution = Resolution::Custom(6);
+        let steps = app.session.history.undo.len();
+        press_ok(&mut app, &ctx, true);
+        assert_eq!(app.session.project.comp(cid).unwrap().resolution, Resolution::Custom(6));
+        assert_eq!(app.session.history.undo.len(), steps, "no undo step");
+        // New Composition makes its comp at the menu's Resolution; the comp the viewer showed keeps its own.
+        open_new_comp(&mut app);
+        app.dialog_state.comp.resolution = Resolution::Quarter;
+        press_ok(&mut app, &ctx, false);
+        let new = app.session.active_comp_id().unwrap();
+        assert_ne!(new, cid);
+        assert_eq!(app.session.project.comp(new).unwrap().resolution, Resolution::Quarter);
+        assert_eq!(app.session.project.comp(cid).unwrap().resolution, Resolution::Custom(6));
+    }
+
     #[test]
     fn composition_settings_register_every_control_and_new_comp_remembers() {
         let (mut app, ctx) = app();
diff --git a/docs/target-app-parity.md b/docs/target-app-parity.md
index 43af6354..ff7cc3ef 100644
--- a/docs/target-app-parity.md
+++ b/docs/target-app-parity.md
@@ -688,8 +688,10 @@ Fixes from measured reports:
   step (undo and redo keep it) and keeps the comp's cached frames; projects saved before open
   with Auto. View ▸ Resolution and the panel's popup run `view.res.full|half|third|quarter|auto`
   and `view.res.custom {factor}`, which now work headless too; `comp.info` reports `resolution`
-  and `resolutionFactor` (#417). Not yet: the magnification is not saved per comp, and the
-  Composition Settings dialog has no Resolution popup.
+  and `resolutionFactor` (#417). Composition Settings ▸ Basic has the same Resolution menu, with
+  the frame size and memory per 8bpc frame at that resolution beside it; OK sets it as the popup
+  does, outside the undo step of the other settings (#2167). Not yet: the magnification is not
+  saved per comp.
 
 ### Update: plug-ins and extensions as in After Effects; ease presets become a ScriptUI panel