diff --git a/package/contents/ui/main.qml b/package/contents/ui/main.qml
index 3601afd..f59bb93 100644
--- a/package/contents/ui/main.qml
+++ b/package/contents/ui/main.qml
@@ -25,4 +25,14 @@ Item {
         flags: Notification.Persistent
         urgency: Notification.HighUrgency
     }
+
+    Notification {
+        id: notificationInvalidPresetWidths
+        componentName: "plasma_workspace"
+        eventId: "notification"
+        title: "Karousel"
+        text: "Your preset widths are malformed, please review your Karousel configuration"
+        flags: Notification.Persistent
+        urgency: Notification.HighUrgency
+    }
 }
diff --git a/src/extern/global.d.ts b/src/extern/global.d.ts
index 48000b4..14c21af 100644
--- a/src/extern/global.d.ts
+++ b/src/extern/global.d.ts
@@ -3,3 +3,4 @@ declare const KWin: KWin;
 declare const Workspace: Workspace;
 declare const qmlBase: QmlObject;
 declare const notificationInvalidWindowRules: Notification;
+declare const notificationInvalidPresetWidths: Notification;
diff --git a/src/lib/config/config.ts b/src/lib/config/config.ts
index db75133..42aa0c6 100644
--- a/src/lib/config/config.ts
+++ b/src/lib/config/config.ts
@@ -7,6 +7,7 @@ type Config = {
     gapsInnerVertical: number;
     manualScrollStep: number;
     manualResizeStep: number;
+    presetWidths: string;
     offScreenOpacity: number;
     untileOnDrag: boolean;
     stackColumnsByDefault: boolean;
diff --git a/src/lib/config/utils.ts b/src/lib/config/utils.ts
new file mode 100644
index 0000000..073cf74
--- /dev/null
+++ b/src/lib/config/utils.ts
@@ -0,0 +1,38 @@
+type PresetWidth = ((screenWidth: number, spacing: number) => number);
+
+function parsePresetWidths(presetWidths: string): PresetWidth[] {
+    function parseNumberSafe(str: string) {
+        const num = Number(str);
+        if (isNaN(num) || num <= 0) {
+            throw new Error("Invalid number: " + str);
+        }
+        return num;
+    }
+
+    function parseNumberWithSuffix(str: string, suffix: string) {
+        if (!str.endsWith(suffix)) {
+            return undefined;
+        }
+        return parseNumberSafe(str.substring(0, str.length-suffix.length).trim());
+    }
+
+    function getRatioFunction(ratio: number) {
+        return (screenWidth: number, spacing: number) => Math.floor((screenWidth + spacing) * ratio - spacing);
+    }
+
+    return presetWidths.split(",").map((widthStr: string) => {
+        widthStr = widthStr.trim();
+
+        const widthPx = parseNumberWithSuffix(widthStr, "px");
+        if (widthPx !== undefined) {
+            return () => widthPx;
+        }
+
+        const widthPct = parseNumberWithSuffix(widthStr, "%");
+        if (widthPct !== undefined) {
+            return getRatioFunction(widthPct / 100.0);
+        }
+
+        return getRatioFunction(parseNumberSafe(widthStr));
+    });
+}
diff --git a/src/lib/keyBindings/Actions.ts b/src/lib/keyBindings/Actions.ts
index 90c81e0..ab17dc9 100644
--- a/src/lib/keyBindings/Actions.ts
+++ b/src/lib/keyBindings/Actions.ts
@@ -316,6 +316,7 @@ namespace Actions {
     export type Config = {
         manualScrollStep: number;
         manualResizeStep: number;
+        presetWidths: PresetWidth[];
         columnResizer: ColumnResizer;
     };
 
diff --git a/src/lib/world/World.ts b/src/lib/world/World.ts
index 2855a0d..73d99e8 100644
--- a/src/lib/world/World.ts
+++ b/src/lib/world/World.ts
@@ -8,9 +8,19 @@ class World {
 
     constructor(config: Config) {
         this.workspaceSignalManager = initWorkspaceSignalHandlers(this);
+
+        let presetWidths: PresetWidth[] = [];
+        try {
+            presetWidths = parsePresetWidths(config.presetWidths);
+        } catch (error: any) {
+            notificationInvalidPresetWidths.sendEvent();
+            log("failed to parse presetWidths:", error);
+        }
+
         this.shortcutActions = registerKeyBindings(this, {
             manualScrollStep: config.manualScrollStep,
             manualResizeStep: config.manualResizeStep,
+            presetWidths: presetWidths,
             columnResizer: config.scrollingCentered ? new RawResizer() : new ContextualResizer(),
         });
 
diff --git a/src/tests/units/config/utils.ts b/src/tests/units/config/utils.ts
new file mode 100644
index 0000000..46f68d1
--- /dev/null
+++ b/src/tests/units/config/utils.ts
@@ -0,0 +1,32 @@
+tests.register("parsePresetWidths", 1, () => {
+    const screenWidth = 800;
+    const spacing = 10;
+
+    const testCases = [
+        { str: "100%, 50%", result: [800, 395] },
+        { str: "100px,50 px", result: [100, 50] },
+        { str: "100px, 25 % , 0.1 ", result: [100, 192, 71] },
+        { str: "100px, 25 % , 0.1p", error: true },
+        { str: "100px, % , 0.1 ", error: true },
+        { str: "100px,  , 0.1 ", error: true },
+        { str: "100px,, 0.1 ", error: true },
+        { str: "100px, 25 % , ", error: true },
+        { str: "asdf", error: true },
+        { str: "", error: true },
+        { str: " ", error: true },
+    ];
+
+    function applyPresetWidths(presetWidths: PresetWidth[]) {
+        return presetWidths.map(f => f(screenWidth, spacing));
+    }
+
+    for (const testCase of testCases) {
+        try {
+            const result = parsePresetWidths(testCase.str);
+            assert(!testCase.error);
+            assertArrayEqual(applyPresetWidths(result), testCase.result!);
+        } catch (error) {
+            assert(testCase.error === true);
+        }
+    }
+});
diff --git a/src/tests/utils/assert.ts b/src/tests/utils/assert.ts
index fb77a66..943ed9a 100644
--- a/src/tests/utils/assert.ts
+++ b/src/tests/utils/assert.ts
@@ -29,6 +29,13 @@ Expected: ${expected}
 Actual: ${actual}`, skip+1);
 }
 
+function assertArrayEqual(actual: any[], expected: any[], skip: number = 0) {
+    const equal = actual.length === expected.length && actual.every((item, index) => item === expected[index]);
+    assert(equal, `Arrays not equal
+Expected: ${expected}
+Actual: ${actual}`, skip+1);
+}
+
 function assertRectEqual(actual: QmlRect, expected: QmlRect, skip: number = 0) {
     assert(rectEquals(expected, actual), `QmlRect not equal
 Expected: ${expected}
diff --git a/src/tests/utils/global.ts b/src/tests/utils/global.ts
index fbc7658..4044c20 100644
--- a/src/tests/utils/global.ts
+++ b/src/tests/utils/global.ts
@@ -3,3 +3,4 @@ let KWin: KWin;
 let Workspace: Workspace;
 let qmlBase: QmlObject;
 let notificationInvalidWindowRules: Notification;
+let notificationInvalidPresetWidths: Notification;