diff --git a/src/App.svelte b/src/App.svelte
index 75e9190..735cd21 100644
--- a/src/App.svelte
+++ b/src/App.svelte
@@ -1,7 +1,10 @@
 <script lang="ts">
+    import Header from "./componentes/header.svelte";
+    import CalcularDias from "./componentes/paginas/CalcularDias.svelte";
     import Tarjeta from "./componentes/tarjeta.svelte";
     import html2canvas from "html2canvas";
 
+    let pagina = $state(0);
     let issues: any[] = $state([]);
     $effect(() => {
         obtener_issues();
@@ -50,24 +53,30 @@
 </script>
 
 <main>
-    <button onclick={() => exportAllToPNG(issues)} class="btn btn-primary mt-3"
-        >Exportar a PNG</button
-    >
-    {#if issues.length == 0}
-        <p>Cargando...</p>
-    {:else}
-        <div class="d-flex justify-center flex-column align-items-center">
-            {#each issues as issue}
-                <div class="m-2 w-75">
-                    <Tarjeta {issue} />
-                    <!--
+    <Header bind:pagina></Header>
+    {#if pagina == 0}
+        <button
+            onclick={() => exportAllToPNG(issues)}
+            class="btn btn-primary mt-3">Exportar a PNG</button
+        >
+        {#if issues.length == 0}
+            <p>Cargando...</p>
+        {:else}
+            <div class="d-flex justify-center flex-column align-items-center">
+                {#each issues as issue}
+                    <div class="m-2 w-75">
+                        <Tarjeta {issue} />
+                        <!--
                     <button
                         onclick={() => exportToPNG(issue)}
                         class="btn btn-primary mt-3">Exportar a PNG</button
                     >
                     -->
-                </div>
-            {/each}
-        </div>
+                    </div>
+                {/each}
+            </div>
+        {/if}
+    {:else if pagina === 1}
+        <CalcularDias {issues} />
     {/if}
 </main>
diff --git a/src/assets/issues.json b/src/assets/issues.json
index 4e7df0e..caac0d4 100644
--- a/src/assets/issues.json
+++ b/src/assets/issues.json
@@ -874,25 +874,6 @@
       "updated_on": "2025-10-22T23:05:58Z",
       "closed_on": "2025-10-22T21:24:48Z"
     },
-    {
-      "id": 7,
-      "project": { "id": 1, "name": "AlquilaFacil" },
-      "tracker": { "id": 1, "name": "Caracteristica" },
-      "status": { "id": 2, "name": "Cerrado", "is_closed": true },
-      "priority": { "id": 2, "name": "Normal" },
-      "author": { "id": 5, "name": "Federico Polidoro" },
-      "subject": "Falta validacion de longitud campo nombre",
-      "description": "![image.png](/attachments/f1c4250a-b349-49f6-9d01-2db5e750bace)\r\n\r\n\u003cimg width=\"389\" alt=\"image.png\" src=\"attachments/b6ed90ae-e622-4ab6-bbf2-dabd58b94717\"\u003e\r\n\r\n",
-      "start_date": "2025-05-29",
-      "due_date": "2025-05-29",
-      "done_ratio": 100,
-      "is_private": false,
-      "estimated_hours": null,
-      "total_estimated_hours": null,
-      "created_on": "2025-10-22T20:58:54Z",
-      "updated_on": "2025-10-22T23:07:19Z",
-      "closed_on": "2025-10-22T21:24:48Z"
-    },
     {
       "id": 6,
       "project": { "id": 1, "name": "AlquilaFacil" },
diff --git a/src/componentes/header.svelte b/src/componentes/header.svelte
new file mode 100644
index 0000000..d52b089
--- /dev/null
+++ b/src/componentes/header.svelte
@@ -0,0 +1,29 @@
+<script>
+    let count = $state(0);
+
+    let { pagina = $bindable() } = $props();
+</script>
+
+<header
+    style="display: flex; justify-content: space-between; align-items: center; padding: 1rem; "
+>
+    <div>
+        <button class="btn btn-primary" onclick={() => (pagina = 0)}
+            >Tarjetas</button
+        >
+        <button class="btn btn-primary" onclick={() => (pagina = 1)}
+            >Dias de duracion</button
+        >
+        <button
+            class="btn"
+            aria-label="Cambiar tema"
+            onclick={() =>
+                document.body.setAttribute(
+                    "data-bs-theme",
+                    document.body.getAttribute("data-bs-theme") === "dark"
+                        ? "light"
+                        : "dark",
+                )}>AAAA me quema los ojos</button
+        >
+    </div>
+</header>
diff --git a/src/componentes/paginas/CalcularDias.svelte b/src/componentes/paginas/CalcularDias.svelte
new file mode 100644
index 0000000..f8c8be3
--- /dev/null
+++ b/src/componentes/paginas/CalcularDias.svelte
@@ -0,0 +1,107 @@
+<script lang="ts">
+    import type { Issue } from "../../types";
+
+    let { issues }: { issues: Issue[] } = $props();
+
+    $effect(() => {
+        calcularDiasPorIssue();
+        calcularDiasTotales();
+    });
+
+    let diasCalculados = $state(0);
+
+    function calcularDiasTotales() {
+        if (!issues || issues.length === 0) {
+            diasCalculados = 0;
+            return;
+        }
+
+        let totalDias = 0;
+
+        let primerIssue = issues.reduce((acc, issue) => {
+            if (!acc.start_date) return issue;
+            if (!issue.start_date) return acc;
+
+            const accDate = new Date(acc.start_date);
+            const issueDate = new Date(issue.start_date);
+
+            return issueDate < accDate ? issue : acc;
+        });
+
+        let ultimoIssue = issues.reduce((acc, issue) => {
+            if (!acc.due_date) return issue;
+            if (!issue.due_date) return acc;
+
+            const accDate = new Date(acc.due_date);
+            const issueDate = new Date(issue.due_date);
+
+            return issueDate > accDate ? issue : acc;
+        });
+
+        if (!primerIssue.start_date || !ultimoIssue.due_date) {
+            diasCalculados = 0;
+            return;
+        }
+
+        const startDate = new Date(primerIssue.start_date);
+        const endDate = new Date(ultimoIssue.due_date);
+
+        if (isNaN(startDate.getTime()) || isNaN(endDate.getTime())) {
+            diasCalculados = 0;
+            return;
+        }
+
+        const diffTime = endDate.getTime() - startDate.getTime();
+        const diffDays = Math.ceil(diffTime / (1000 * 60 * 60 * 24));
+        diasCalculados = diffDays > 0 ? diffDays : 0;
+    }
+
+    function calcularDiasPorIssue() {
+        issues.forEach((issue) => {
+            if (issue.start_date && issue.due_date) {
+                const startDate = new Date(issue.start_date);
+                const dueDate = new Date(issue.due_date);
+
+                if (!isNaN(startDate.getTime()) && !isNaN(dueDate.getTime())) {
+                    const diffTime = dueDate.getTime() - startDate.getTime();
+                    const diffDays = Math.ceil(
+                        diffTime / (1000 * 60 * 60 * 24),
+                    );
+                    issue.cantDias = diffDays;
+                }
+            }
+        });
+    }
+</script>
+
+<div class="container mt-4">
+    <div class="card">
+        <div class="card-header bg-primary text-white">
+            <h5 class="mb-0">Calculadora de Días</h5>
+        </div>
+        <div class="card-body">
+            {#if diasCalculados > 0}
+                <div class="alert alert-info">
+                    <strong>Resultado:</strong>
+                    {diasCalculados} días calculados
+                </div>
+            {/if}
+
+            <div class="mt-3">
+                <h6>Issues:</h6>
+                <ul class="list-group">
+                    {#each issues as issue}
+                        <li
+                            class="list-group-item d-flex justify-content-between align-items-center"
+                        >
+                            {`${issue.id} | ${issue.subject}`}
+                            <span class="badge bg-secondary"
+                                >{issue.cantDias || 0} días</span
+                            >
+                        </li>
+                    {/each}
+                </ul>
+            </div>
+        </div>
+    </div>
+</div>
diff --git a/src/types.d.ts b/src/types.d.ts
new file mode 100644
index 0000000..b3cee0b
--- /dev/null
+++ b/src/types.d.ts
@@ -0,0 +1,20 @@
+export interface Issue {
+  id: number;
+  project: { id: number; name: string };
+  tracker: { id: number; name: string };
+  status: { id: number; name: string; is_closed: boolean };
+  priority: { id: number; name: string };
+  author: { id: number; name: string };
+  subject: string;
+  description: string;
+  start_date: string;
+  due_date: string;
+  cantDias: number;
+  done_ratio: number;
+  is_private: boolean;
+  estimated_hours: number | null;
+  total_estimated_hours: number | null;
+  created_on: string;
+  updated_on: string;
+  closed_on: string;
+}