diff --git a/newtab.html b/newtab.html
index dd0bd02..c6bc824 100644
--- a/newtab.html
+++ b/newtab.html
@@ -510,6 +510,7 @@
   <script src="src/js/calc-scientific.js"></script>
   <script src="src/js/calc-converter.js"></script>
   <script src="src/js/calc-satisfactory.js"></script>
+  <script src="src/js/calc-factorio.js"></script>
   <script src="src/js/timer.js"></script>
   <script src="src/js/image-ref.js"></script>
   <script src="src/js/bookmark-import.js"></script>
diff --git a/src/js/calc-factorio.js b/src/js/calc-factorio.js
new file mode 100644
index 0000000..d08085b
--- /dev/null
+++ b/src/js/calc-factorio.js
@@ -0,0 +1,247 @@
+/* =============================================
+   HELLION NEWTAB — calc-factorio.js
+   Factorio Calculator Modus
+   ============================================= */
+
+(function() {
+  'use strict';
+
+  const ASSEMBLERS = [
+    { key: 'asm1', speed: 0.5 },
+    { key: 'asm2', speed: 0.75 },
+    { key: 'asm3', speed: 1.25 }
+  ];
+
+  const BELTS = [
+    { key: 'yellow', throughput: 15, perSide: 7.5 },
+    { key: 'red',    throughput: 30, perSide: 15 },
+    { key: 'blue',   throughput: 45, perSide: 22.5 }
+  ];
+
+  const SUB_MODES = ['ratio', 'belt', 'machines'];
+  let _activeSubMode = 'ratio';
+
+  function createAssemblerSelect(selectedKey) {
+    const row = document.createElement('div');
+    row.className = 'calc-game-field';
+    const label = document.createElement('label');
+    label.textContent = t('calculator.fac.assembler');
+    const select = document.createElement('select');
+    select.className = 'calc-game-input';
+    ASSEMBLERS.forEach(asm => {
+      const opt = document.createElement('option');
+      opt.value = asm.key;
+      opt.textContent = t('calculator.fac.asm.' + asm.key) + ' (' + asm.speed + 'x)';
+      if (asm.key === selectedKey) opt.selected = true;
+      select.appendChild(opt);
+    });
+    row.append(label, select);
+    return { row, select };
+  }
+
+  function createBeltSelect(selectedKey) {
+    const row = document.createElement('div');
+    row.className = 'calc-game-field';
+    const label = document.createElement('label');
+    label.textContent = t('calculator.fac.belt');
+    const select = document.createElement('select');
+    select.className = 'calc-game-input';
+    BELTS.forEach(belt => {
+      const opt = document.createElement('option');
+      opt.value = belt.key;
+      opt.textContent = t('calculator.fac.belt.' + belt.key) + ' (' + belt.throughput + '/s)';
+      if (belt.key === selectedKey) opt.selected = true;
+      select.appendChild(opt);
+    });
+    row.append(label, select);
+    return { row, select };
+  }
+
+  function getAssemblerSpeed(key) {
+    const asm = ASSEMBLERS.find(a => a.key === key);
+    return asm ? asm.speed : 1;
+  }
+
+  function getBelt(key) {
+    return BELTS.find(b => b.key === key) || BELTS[0];
+  }
+
+  function findSmallestBelt(throughput) {
+    for (const belt of BELTS) {
+      if (belt.throughput >= throughput) return belt;
+    }
+    return null;
+  }
+
+  function createField(labelKey, defaultVal, opts) {
+    opts = opts || {};
+    const row = document.createElement('div');
+    row.className = 'calc-game-field';
+    const label = document.createElement('label');
+    label.textContent = t(labelKey);
+    const input = document.createElement('input');
+    input.type = 'number';
+    input.className = 'calc-game-input';
+    input.value = defaultVal;
+    if (opts.step) input.step = opts.step;
+    if (opts.min !== undefined) input.min = opts.min;
+    row.append(label, input);
+    return { row, input };
+  }
+
+  function createOutput(labelKey) {
+    const row = document.createElement('div');
+    row.className = 'calc-game-output';
+    const label = document.createElement('span');
+    label.textContent = t(labelKey);
+    const value = document.createElement('span');
+    value.className = 'calc-game-value';
+    row.append(label, value);
+    return { row, value };
+  }
+
+  function renderRatio(container) {
+    const asmSelect = createAssemblerSelect('asm3');
+    const outputField = createField('calculator.fac.recipe_output', 1, { step: 1, min: 1 });
+    const timeField = createField('calculator.fac.recipe_time', 1, { step: 0.1, min: 0.1 });
+    const perSecOutput = createOutput('calculator.fac.items_per_sec');
+    const perMinOutput = createOutput('calculator.fac.items_per_min');
+
+    function calc() {
+      const speed = getAssemblerSpeed(asmSelect.select.value);
+      const output = parseFloat(outputField.input.value) || 0;
+      const time = parseFloat(timeField.input.value) || 1;
+      const perSec = output * speed / time;
+      const perMin = perSec * 60;
+      perSecOutput.value.textContent = Calculator._formatResult(perSec) + ' /s';
+      perMinOutput.value.textContent = Calculator._formatResult(perMin) + ' /min';
+    }
+
+    [outputField, timeField].forEach(f => f.input.addEventListener('input', calc));
+    asmSelect.select.addEventListener('change', calc);
+    container.append(asmSelect.row, outputField.row, timeField.row, perSecOutput.row, perMinOutput.row);
+    calc();
+  }
+
+  function renderBelt(container) {
+    const beltSelect = createBeltSelect('yellow');
+    const consumeField = createField('calculator.fac.consume_per_sec', 1, { step: 0.1, min: 0.1 });
+    const machinesOutput = createOutput('calculator.fac.machines_per_belt');
+    const utilOutput = createOutput('calculator.fac.belt_utilization');
+
+    function calc() {
+      const belt = getBelt(beltSelect.select.value);
+      const consume = parseFloat(consumeField.input.value) || 1;
+      const machines = Math.floor(belt.throughput / consume);
+      const util = (consume * machines) / belt.throughput * 100;
+      machinesOutput.value.textContent = machines;
+      utilOutput.value.textContent = Calculator._formatResult(util) + '%';
+    }
+
+    consumeField.input.addEventListener('input', calc);
+    beltSelect.select.addEventListener('change', calc);
+    container.append(beltSelect.row, consumeField.row, machinesOutput.row, utilOutput.row);
+    calc();
+  }
+
+  function renderMachines(container) {
+    const asmSelect = createAssemblerSelect('asm3');
+    const targetField = createField('calculator.fac.target_output_sec', 10, { step: 0.1, min: 0.1 });
+    const outputField = createField('calculator.fac.recipe_output', 1, { step: 1, min: 1 });
+    const timeField = createField('calculator.fac.recipe_time', 1, { step: 0.1, min: 0.1 });
+    const machinesOutput = createOutput('calculator.fac.machines_needed');
+    const beltOutput = createOutput('calculator.fac.belt_needed');
+
+    function calc() {
+      const speed = getAssemblerSpeed(asmSelect.select.value);
+      const target = parseFloat(targetField.input.value) || 0;
+      const output = parseFloat(outputField.input.value) || 1;
+      const time = parseFloat(timeField.input.value) || 1;
+      const perMachine = output * speed / time;
+      const machines = perMachine > 0 ? Math.ceil(target / perMachine) : 0;
+      const totalThroughput = machines * perMachine;
+      const belt = findSmallestBelt(totalThroughput);
+
+      machinesOutput.value.textContent = machines;
+      if (belt) {
+        const util = (totalThroughput / belt.throughput) * 100;
+        beltOutput.value.textContent = t('calculator.fac.belt.' + belt.key) + ' (' + Calculator._formatResult(util) + '%)';
+      } else {
+        beltOutput.value.textContent = t('calculator.fac.exceeds_belt');
+      }
+    }
+
+    [targetField, outputField, timeField].forEach(f => f.input.addEventListener('input', calc));
+    asmSelect.select.addEventListener('change', calc);
+    container.append(asmSelect.row, targetField.row, outputField.row, timeField.row, machinesOutput.row, beltOutput.row);
+    calc();
+  }
+
+  async function loadState() {
+    const data = await Store.get(Calculator.STORAGE_KEY);
+    if (data && data.calculator && data.calculator.factorio) {
+      const s = data.calculator.factorio;
+      if (s.lastSubMode && SUB_MODES.includes(s.lastSubMode)) _activeSubMode = s.lastSubMode;
+    }
+  }
+
+  async function saveState() {
+    const data = await Store.get(Calculator.STORAGE_KEY) || {};
+    if (!data.calculator) data.calculator = {};
+    data.calculator.factorio = { lastSubMode: _activeSubMode };
+    await Store.set(Calculator.STORAGE_KEY, data);
+  }
+
+  function renderSubMode(container) {
+    container.textContent = '';
+    switch (_activeSubMode) {
+      case 'ratio':    renderRatio(container); break;
+      case 'belt':     renderBelt(container); break;
+      case 'machines': renderMachines(container); break;
+    }
+  }
+
+  Calculator.registerMode('factorio', {
+    label: '🏭',
+    shortName: 'FAC',
+    titleKey: 'calculator.tab.factorio',
+
+    render(bodyEl) {
+      bodyEl.style.padding = '8px';
+      bodyEl.style.display = 'flex';
+      bodyEl.style.flexDirection = 'column';
+      bodyEl.style.gap = '8px';
+
+      loadState().then(() => {
+        const subContent = document.createElement('div');
+        subContent.className = 'calc-game-content';
+
+        const bar = document.createElement('div');
+        bar.className = 'calc-game-subtabs';
+
+        SUB_MODES.forEach(mode => {
+          const btn = document.createElement('button');
+          btn.type = 'button';
+          btn.className = 'calc-game-subtab' + (mode === _activeSubMode ? ' active' : '');
+          btn.textContent = t('calculator.fac.tab.' + mode);
+          btn.dataset.mode = mode;
+          btn.addEventListener('click', () => {
+            bar.querySelectorAll('.calc-game-subtab').forEach(b => b.classList.remove('active'));
+            btn.classList.add('active');
+            _activeSubMode = mode;
+            renderSubMode(subContent);
+            saveState();
+          });
+          bar.appendChild(btn);
+        });
+
+        bodyEl.append(bar, subContent);
+        renderSubMode(subContent);
+      });
+    },
+
+    destroy() {
+      saveState();
+    }
+  });
+})();
diff --git a/src/js/i18n.js b/src/js/i18n.js
index 5bfc326..ca0722d 100644
--- a/src/js/i18n.js
+++ b/src/js/i18n.js
@@ -123,6 +123,31 @@ const STRINGS = {
     'calculator.sat.machines_needed':    'Maschinen benötigt',
     'calculator.sat.total_power':        'Gesamtleistung',
 
+    // Factorio Calculator
+    'calculator.tab.factorio':           'Factorio',
+    'calculator.fac.tab.ratio':          'Ratio',
+    'calculator.fac.tab.belt':           'Belt',
+    'calculator.fac.tab.machines':       'Maschinen',
+    'calculator.fac.assembler':          'Assembler',
+    'calculator.fac.asm.asm1':           'Assembler 1',
+    'calculator.fac.asm.asm2':           'Assembler 2',
+    'calculator.fac.asm.asm3':           'Assembler 3',
+    'calculator.fac.belt':               'Belt-Typ',
+    'calculator.fac.belt.yellow':        'Gelb',
+    'calculator.fac.belt.red':           'Rot',
+    'calculator.fac.belt.blue':          'Blau',
+    'calculator.fac.recipe_output':      'Rezept-Output',
+    'calculator.fac.recipe_time':        'Rezeptzeit (s)',
+    'calculator.fac.consume_per_sec':    'Verbrauch/s',
+    'calculator.fac.target_output_sec':  'Ziel Output/s',
+    'calculator.fac.items_per_sec':      'Items/s',
+    'calculator.fac.items_per_min':      'Items/min',
+    'calculator.fac.machines_per_belt':  'Maschinen/Belt',
+    'calculator.fac.belt_utilization':   'Belt-Auslastung',
+    'calculator.fac.machines_needed':    'Maschinen benötigt',
+    'calculator.fac.belt_needed':        'Belt benötigt',
+    'calculator.fac.exceeds_belt':       'Übersteigt max. Belt',
+
     // Timer
     'timer.title':             'Timer',
     'timer.start':             'Start',
@@ -470,6 +495,31 @@ const STRINGS = {
     'calculator.sat.machines_needed':    'Machines needed',
     'calculator.sat.total_power':        'Total Power',
 
+    // Factorio Calculator
+    'calculator.tab.factorio':           'Factorio',
+    'calculator.fac.tab.ratio':          'Ratio',
+    'calculator.fac.tab.belt':           'Belt',
+    'calculator.fac.tab.machines':       'Machines',
+    'calculator.fac.assembler':          'Assembler',
+    'calculator.fac.asm.asm1':           'Assembler 1',
+    'calculator.fac.asm.asm2':           'Assembler 2',
+    'calculator.fac.asm.asm3':           'Assembler 3',
+    'calculator.fac.belt':               'Belt Type',
+    'calculator.fac.belt.yellow':        'Yellow',
+    'calculator.fac.belt.red':           'Red',
+    'calculator.fac.belt.blue':          'Blue',
+    'calculator.fac.recipe_output':      'Recipe Output',
+    'calculator.fac.recipe_time':        'Recipe Time (s)',
+    'calculator.fac.consume_per_sec':    'Consume/s',
+    'calculator.fac.target_output_sec':  'Target Output/s',
+    'calculator.fac.items_per_sec':      'Items/s',
+    'calculator.fac.items_per_min':      'Items/min',
+    'calculator.fac.machines_per_belt':  'Machines/Belt',
+    'calculator.fac.belt_utilization':   'Belt Utilization',
+    'calculator.fac.machines_needed':    'Machines needed',
+    'calculator.fac.belt_needed':        'Belt needed',
+    'calculator.fac.exceeds_belt':       'Exceeds max belt',
+
     // Timer
     'timer.title':             'Timer',
     'timer.start':             'Start',