diff --git a/core/src/PageMapping.ts b/core/src/PageMapping.ts
index a1fcccb..98a0585 100644
--- a/core/src/PageMapping.ts
+++ b/core/src/PageMapping.ts
@@ -2,7 +2,7 @@
  * Holds the information which (zero based) page index maps to a page number.
  */
 export default class PageMapping {
-  constructor(public pageFactor: number, public detectedOnPage: boolean) {}
+  constructor(public pageFactor: number = 1, public detectedOnPage: boolean = false) {}
 
   /**
    * Translates a given page index to a page number label as printed on the page. E.g [0,1,2,3,4] could become [I, II, 1, 2].
@@ -10,10 +10,14 @@ export default class PageMapping {
    */
   pageLabel(pageIndex: number) {
     const pageNumber = pageIndex + this.pageFactor;
-    if (pageNumber < 0) {
-      return romanize(pageNumber - this.pageFactor + 1);
+    if (pageNumber < 1) {
+      return romanize(Math.abs(pageNumber - this.pageFactor) + 1);
     }
-    return `${pageNumber + 1}`;
+    return `${pageNumber}`;
+  }
+
+  shifted(): boolean {
+    return this.pageFactor != 1;
   }
 }
 
diff --git a/core/src/transformer/CacluclateStatistics.ts b/core/src/transformer/CacluclateStatistics.ts
index dc6ff9d..6c9bf74 100644
--- a/core/src/transformer/CacluclateStatistics.ts
+++ b/core/src/transformer/CacluclateStatistics.ts
@@ -73,7 +73,6 @@ export default class CalculateStatistics extends ItemTransformer {
 
     const groupedByPage = groupByPage(items);
     const pageMapping = parsePageMapping(groupedByPage, minX, maxX, minY, maxY);
-    console.log(pageMapping);
 
     // Parse line distances
     const distanceToOccurrence = {};
@@ -165,7 +164,7 @@ function parsePageMapping(
     }),
     { sampleCount: 20, minFulfillment: 0.8 },
   );
-  return typeof pageFactor === 'undefined' ? new PageMapping(0, false) : new PageMapping(pageFactor, true);
+  return typeof pageFactor === 'undefined' ? new PageMapping() : new PageMapping(pageFactor, true);
 }
 
 function getMostUsedKey(keyToOccurrence): any {
diff --git a/core/src/transformer/Globals.ts b/core/src/transformer/Globals.ts
index 22f548f..8ba0a5c 100644
--- a/core/src/transformer/Globals.ts
+++ b/core/src/transformer/Globals.ts
@@ -25,6 +25,10 @@ export default class Globals {
     return element;
   }
 
+  getOptional<T>(definition: GlobalDefinition<T>): T | undefined {
+    return this.map.get(definition.key) as T;
+  }
+
   set<T>(definition: GlobalDefinition<T>, value: T) {
     assertNot(this.isDefined(definition), `Global with key '${definition.key}' already registered.`);
     this.map.set(definition.key, value);
diff --git a/core/test/PageMapping.test.ts b/core/test/PageMapping.test.ts
index c6b033a..622b1b2 100644
--- a/core/test/PageMapping.test.ts
+++ b/core/test/PageMapping.test.ts
@@ -1,12 +1,17 @@
 import PageMapping from 'src/PageMapping';
 
 test('1-to-1', async () => {
-  const mapping = new PageMapping(0, false);
-  expect(mapping.pageFactor).toEqual(0);
+  const mapping = new PageMapping(1, false);
+  expect(mapping.pageFactor).toEqual(1);
   expect([...Array(3).keys()].map((i) => mapping.pageLabel(i))).toEqual(['1', '2', '3']);
 });
 
-test('lame start', async () => {
-  const mapping = new PageMapping(-3, true);
+test('one starter page', async () => {
+  const mapping = new PageMapping(0, true);
+  expect([...Array(5).keys()].map((i) => mapping.pageLabel(i))).toEqual(['I', '1', '2', '3', '4']);
+});
+
+test('three starter pages', async () => {
+  const mapping = new PageMapping(-2, true);
   expect([...Array(5).keys()].map((i) => mapping.pageLabel(i))).toEqual(['I', 'II', 'III', '1', '2']);
 });
diff --git a/core/test/transformer/Globals.test.ts b/core/test/transformer/Globals.test.ts
index 46be0b2..68050f7 100644
--- a/core/test/transformer/Globals.test.ts
+++ b/core/test/transformer/Globals.test.ts
@@ -8,6 +8,7 @@ test('not set', async () => {
   const globals = new Globals();
   globals.set(MyGlobalString, '23');
   expect(globals.isDefined(MyGlobalNumber)).toBeFalsy();
+  expect(globals.getOptional(MyGlobalNumber)).toBeUndefined();
   expect(() => globals.get(MyGlobalNumber)).toThrow(
     `No global with key '${MyGlobalNumber.key}' registered. Only [${MyGlobalString.key}]`,
   );
@@ -19,6 +20,7 @@ test('set', async () => {
 
   expect(globals.isDefined(MyGlobalNumber)).toBeTruthy();
   expect(globals.get(MyGlobalNumber)).toEqual(24);
+  expect(globals.getOptional(MyGlobalNumber)).toEqual(24);
   expect(globals.keys()).toEqual([MyGlobalNumber.key]);
 });
 
diff --git a/examples/Flash-Masques-Temperature/calculateStatistics.json b/examples/Flash-Masques-Temperature/calculateStatistics.json
index d1f508a..420fda6 100644
--- a/examples/Flash-Masques-Temperature/calculateStatistics.json
+++ b/examples/Flash-Masques-Temperature/calculateStatistics.json
@@ -33,7 +33,7 @@
     "minY": 36.1763,
     "maxY": 811.1348,
     "pageMapping": {
-      "pageFactor": 0,
+      "pageFactor": 1,
       "detectedOnPage": false
     }
   }
diff --git a/examples/Flash-Masques-Temperature/compactLines.json b/examples/Flash-Masques-Temperature/compactLines.json
index 53fb758..143b4df 100644
--- a/examples/Flash-Masques-Temperature/compactLines.json
+++ b/examples/Flash-Masques-Temperature/compactLines.json
@@ -37,7 +37,7 @@
     "minY": 36.1763,
     "maxY": 811.1348,
     "pageMapping": {
-      "pageFactor": 0,
+      "pageFactor": 1,
       "detectedOnPage": false
     }
   }
diff --git a/examples/Flash-Masques-Temperature/removeRepetitiveItems.json b/examples/Flash-Masques-Temperature/removeRepetitiveItems.json
index 2648987..fca8fb4 100644
--- a/examples/Flash-Masques-Temperature/removeRepetitiveItems.json
+++ b/examples/Flash-Masques-Temperature/removeRepetitiveItems.json
@@ -36,7 +36,7 @@
     "minY": 36.1763,
     "maxY": 811.1348,
     "pageMapping": {
-      "pageFactor": 0,
+      "pageFactor": 1,
       "detectedOnPage": false
     }
   }
diff --git a/examples/Flash-Masques-Temperature/sortbyX.json b/examples/Flash-Masques-Temperature/sortbyX.json
index a559535..3680966 100644
--- a/examples/Flash-Masques-Temperature/sortbyX.json
+++ b/examples/Flash-Masques-Temperature/sortbyX.json
@@ -36,7 +36,7 @@
     "minY": 36.1763,
     "maxY": 811.1348,
     "pageMapping": {
-      "pageFactor": 0,
+      "pageFactor": 1,
       "detectedOnPage": false
     }
   }
diff --git a/examples/The-Art-of-Public-Speaking/calculateStatistics.0.json b/examples/The-Art-of-Public-Speaking/calculateStatistics.0.json
index 0122d6c..f058476 100644
--- a/examples/The-Art-of-Public-Speaking/calculateStatistics.0.json
+++ b/examples/The-Art-of-Public-Speaking/calculateStatistics.0.json
@@ -33,7 +33,7 @@
     "minY": 75.60000000000002,
     "maxY": 712.8,
     "pageMapping": {
-      "pageFactor": 0,
+      "pageFactor": 1,
       "detectedOnPage": false
     }
   }
diff --git a/examples/The-Art-of-Public-Speaking/compactLines.json b/examples/The-Art-of-Public-Speaking/compactLines.json
index 2dc1e43..f62b49e 100644
--- a/examples/The-Art-of-Public-Speaking/compactLines.json
+++ b/examples/The-Art-of-Public-Speaking/compactLines.json
@@ -37,7 +37,7 @@
     "minY": 75.60000000000002,
     "maxY": 712.8,
     "pageMapping": {
-      "pageFactor": 0,
+      "pageFactor": 1,
       "detectedOnPage": false
     }
   }
diff --git a/examples/The-Art-of-Public-Speaking/removeRepetitiveItems.json b/examples/The-Art-of-Public-Speaking/removeRepetitiveItems.json
index 10a46fa..8cef420 100644
--- a/examples/The-Art-of-Public-Speaking/removeRepetitiveItems.json
+++ b/examples/The-Art-of-Public-Speaking/removeRepetitiveItems.json
@@ -36,7 +36,7 @@
     "minY": 75.60000000000002,
     "maxY": 712.8,
     "pageMapping": {
-      "pageFactor": 0,
+      "pageFactor": 1,
       "detectedOnPage": false
     }
   }
diff --git a/examples/The-Art-of-Public-Speaking/sortbyX.json b/examples/The-Art-of-Public-Speaking/sortbyX.json
index 1f318ef..fea1aa5 100644
--- a/examples/The-Art-of-Public-Speaking/sortbyX.json
+++ b/examples/The-Art-of-Public-Speaking/sortbyX.json
@@ -36,7 +36,7 @@
     "minY": 75.60000000000002,
     "maxY": 712.8,
     "pageMapping": {
-      "pageFactor": 0,
+      "pageFactor": 1,
       "detectedOnPage": false
     }
   }
diff --git a/examples/The-Man-Without-A-Body/calculateStatistics.json b/examples/The-Man-Without-A-Body/calculateStatistics.json
index 28fcfd1..8b6d4e2 100644
--- a/examples/The-Man-Without-A-Body/calculateStatistics.json
+++ b/examples/The-Man-Without-A-Body/calculateStatistics.json
@@ -33,7 +33,7 @@
     "minY": 75.025,
     "maxY": 747.22,
     "pageMapping": {
-      "pageFactor": 0,
+      "pageFactor": 1,
       "detectedOnPage": false
     }
   }
diff --git a/examples/The-Man-Without-A-Body/compactLines.json b/examples/The-Man-Without-A-Body/compactLines.json
index 28a0155..e57bdb2 100644
--- a/examples/The-Man-Without-A-Body/compactLines.json
+++ b/examples/The-Man-Without-A-Body/compactLines.json
@@ -37,7 +37,7 @@
     "minY": 75.025,
     "maxY": 747.22,
     "pageMapping": {
-      "pageFactor": 0,
+      "pageFactor": 1,
       "detectedOnPage": false
     }
   }
diff --git a/examples/The-Man-Without-A-Body/removeRepetitiveItems.json b/examples/The-Man-Without-A-Body/removeRepetitiveItems.json
index 0bf0ec0..19f1c4d 100644
--- a/examples/The-Man-Without-A-Body/removeRepetitiveItems.json
+++ b/examples/The-Man-Without-A-Body/removeRepetitiveItems.json
@@ -36,7 +36,7 @@
     "minY": 75.025,
     "maxY": 747.22,
     "pageMapping": {
-      "pageFactor": 0,
+      "pageFactor": 1,
       "detectedOnPage": false
     }
   }
diff --git a/examples/The-Man-Without-A-Body/sortbyX.json b/examples/The-Man-Without-A-Body/sortbyX.json
index 0bf0ec0..19f1c4d 100644
--- a/examples/The-Man-Without-A-Body/sortbyX.json
+++ b/examples/The-Man-Without-A-Body/sortbyX.json
@@ -36,7 +36,7 @@
     "minY": 75.025,
     "maxY": 747.22,
     "pageMapping": {
-      "pageFactor": 0,
+      "pageFactor": 1,
       "detectedOnPage": false
     }
   }
diff --git a/examples/compressed.tracemonkey-pldi-09/removeRepetitiveItems.json b/examples/compressed.tracemonkey-pldi-09/removeRepetitiveItems.json
index 596dd7a..9ca213e 100644
--- a/examples/compressed.tracemonkey-pldi-09/removeRepetitiveItems.json
+++ b/examples/compressed.tracemonkey-pldi-09/removeRepetitiveItems.json
@@ -36,7 +36,7 @@
     "minY": 68.44329999999982,
     "maxY": 713.7734000000003,
     "pageMapping": {
-      "pageFactor": 0,
+      "pageFactor": 1,
       "detectedOnPage": false
     }
   }
diff --git a/ui/src/debug/CurrentPage.svelte b/ui/src/debug/CurrentPage.svelte
index 6d1dd69..a3e2be3 100644
--- a/ui/src/debug/CurrentPage.svelte
+++ b/ui/src/debug/CurrentPage.svelte
@@ -11,7 +11,7 @@
     export let pageControl: PageControl;
     export let pageIndex: number;
 
-    let { pagePinned, canPrev, canNext } = pageControl;
+    let { pagePinned, canPrev, canNext, pageMapping } = pageControl;
 </script>
 
 <div class="flex items-center space-x-1">
@@ -20,7 +20,13 @@
             <Icon class="text-xs hover:text-select hover:opacity-25 cursor-pointer opacity-75" icon={pin} />
         </span>
     {/if}
-    <div>Page {pageIndex + 1} {$pagePinned ? '' : ' / ' + pageControl.totalPages}</div>
+    <div>
+        Page
+        {$pageMapping.pageLabel(pageIndex)}
+        {#if $pageMapping.shifted()}
+            <span class="font-light"> ({pageIndex + 1}/{pageControl.totalPages}) </span>
+        {:else}/ {pageControl.totalPages + $pageMapping.pageFactor - 1}{/if}
+    </div>
 </div>
 {#if $pagePinned}
     <div class="absolute flex ml-4 space-x-2">
diff --git a/ui/src/debug/DebugView.svelte b/ui/src/debug/DebugView.svelte
index 879705f..aab73b7 100644
--- a/ui/src/debug/DebugView.svelte
+++ b/ui/src/debug/DebugView.svelte
@@ -3,6 +3,7 @@
     import { flip } from 'svelte/animate';
 
     import type Debugger from '@core/Debugger';
+    import { PAGE_MAPPING } from '../../../core/src/transformer/CacluclateStatistics';
 
     import { debugStage } from '../config';
     import ControlBar from './ControlBar.svelte';
@@ -19,6 +20,7 @@
     let onlyRelevantItems = true;
 
     $: stageResult = debug.stageResult($debugStage);
+    $: pageControl.updateMapping(stageResult.globals.getOptional(PAGE_MAPPING));
     $: supportsGrouping = !!stageResult.descriptor?.debug?.itemMerger;
     $: supportsRelevanceFiltering = !stageResult.descriptor?.debug?.showAll;
     $: visiblePages = pageControl.selectPages(stageResult, onlyRelevantItems, groupingEnabled, $pinnedPageIndex);
diff --git a/ui/src/debug/PageControl.ts b/ui/src/debug/PageControl.ts
index 059875a..3ded1d6 100644
--- a/ui/src/debug/PageControl.ts
+++ b/ui/src/debug/PageControl.ts
@@ -1,5 +1,5 @@
-import Page from '@core/debug/Page';
 import StageResult from '@core/debug/StageResult';
+import PageMapping from '../../../core/src/PageMapping';
 import { Writable, writable, get, Readable, derived } from 'svelte/store';
 
 export default class PageControl {
@@ -8,6 +8,7 @@ export default class PageControl {
     canPrev: Readable<boolean>;
     canNext: Readable<boolean>;
     pagesWithItems: Set<number> = new Set();
+    pageMapping: Writable<PageMapping> = writable(new PageMapping());
 
     constructor(public totalPages: number) {
         this.pinnedPageIndex = writable(undefined);
@@ -22,6 +23,12 @@ export default class PageControl {
         this.unpinPage.bind(this);
     }
 
+    updateMapping(pageMapping: PageMapping | undefined) {
+        if (pageMapping) {
+            this.pageMapping.set(pageMapping);
+        }
+    }
+
     selectPages(stageResult: StageResult, relevantChangesOnly: boolean, groupItems: boolean, pinnedPage?: number) {
         const allRelevantPages = stageResult.selectPages(relevantChangesOnly, groupItems);
         this.pagesWithItems = new Set(
diff --git a/ui/src/debug/PageSelectionPopup.svelte b/ui/src/debug/PageSelectionPopup.svelte
index 6bd85bb..39fcac4 100644
--- a/ui/src/debug/PageSelectionPopup.svelte
+++ b/ui/src/debug/PageSelectionPopup.svelte
@@ -8,7 +8,8 @@
 
     export let pageControl: PageControl;
 
-    let { pinnedPageIndex, pagePinned } = pageControl;
+    let { pinnedPageIndex, pagePinned, pageMapping } = pageControl;
+    let showIndex = false;
 
     const popupOpened: Writable<boolean> = getContext('popupOpened');
 
@@ -34,7 +35,7 @@
             <div
                 on:click={() => pageControl.pageHasItems(idx) && pinPage(idx)}
                 class="px-2 border border-gray-300 rounded-full text-center  {pageControl.pageHasItems(idx) ? ($pinnedPageIndex === idx ? 'bg-select' : 'hover:text-select hover:border-select cursor-pointer') : 'opacity-50'}">
-                {idx + 1}
+                {#if showIndex}{idx}{:else}{$pageMapping.pageLabel(idx)}{/if}
             </div>
         {/each}
     </div>