diff --git a/app.py b/app.py
index 9f13ee1..8dd0654 100644
--- a/app.py
+++ b/app.py
@@ -144,14 +144,19 @@ def create_app(config_object="config"):
             purchase_date    = f.get("purchase_date", "").strip() or None
             storage_location = f.get("storage_location", "").strip() or None
 
+            include_size = f.get("include_size_in_label") == "on"
+            label_prefix = f"{brand} {size}" if include_size and size else brand
+
             existing_labels = [
                 r[0] for r in db.query(Battery.label).filter(Battery.brand == brand).all()
             ]
-            nums = [int(m.group(1)) for lbl in existing_labels
+            prefix_labels = [lbl for lbl in existing_labels
+                             if lbl == label_prefix or lbl.startswith(label_prefix + " ")]
+            nums = [int(m.group(1)) for lbl in prefix_labels
                     if (m := re.search(r'(\d+)$', lbl))]
             next_num = max(nums, default=0)
             for i in range(count):
-                label = f"{brand} {next_num + i + 1:03d}"
+                label = f"{label_prefix} {next_num + i + 1:03d}"
                 db.add(Battery(label=label, brand=brand, status="available", notes=notes,
                                size=size, chemistry=chemistry, capacity_mah=capacity_mah,
                                purchase_date=purchase_date, storage_location=storage_location))
@@ -165,14 +170,21 @@ def create_app(config_object="config"):
             .filter(Battery.storage_location.isnot(None))
             .distinct().order_by(Battery.storage_location).all()
         ]
-        brand_counts = {
-            r[0]: r[1]
-            for r in db.query(Battery.brand, func.count(Battery.id))
-                       .group_by(Battery.brand).all()
-        }
+        prefix_max_nums = {}
+        for lbl, brand, size in db.query(Battery.label, Battery.brand, Battery.size).all():
+            m = re.search(r'(\d+)$', lbl)
+            if not m:
+                continue
+            num = int(m.group(1))
+            if num > prefix_max_nums.get(brand, 0):
+                prefix_max_nums[brand] = num
+            if size:
+                key = f"{brand} {size}"
+                if num > prefix_max_nums.get(key, 0):
+                    prefix_max_nums[key] = num
         return render_template("battery_add.html", form_count=1, brands=brands,
                                storage_locations=storage_locations,
-                               brand_counts=brand_counts)
+                               prefix_max_nums=prefix_max_nums)
 
     # ------------------------------------------------------------------ #
     # Battery — detail
diff --git a/templates/battery_add.html b/templates/battery_add.html
index c187b43..95c1832 100644
--- a/templates/battery_add.html
+++ b/templates/battery_add.html
@@ -27,6 +27,12 @@
         <label for="count">Quantity</label>
         <input type="number" id="count" name="count" value="{{ form_count|default(1) }}" min="1" max="50">
         <small class="text-muted">Labels are auto-generated (e.g. Eneloop 001, Eneloop 002)</small>
+        <div style="margin-top:0.4rem;">
+          <label style="display:inline-flex;align-items:center;gap:0.4rem;font-weight:normal;cursor:pointer;">
+            <input type="checkbox" id="include_size_in_label" name="include_size_in_label">
+            Include size in label (e.g. Eneloop AAA 001)
+          </label>
+        </div>
         <div id="label-preview" style="font-size:0.85rem;color:var(--link);margin-top:0.3rem;font-weight:500;min-height:1.2em;"></div>
       </div>
 
@@ -97,7 +103,7 @@
 </div>
 
 <script>
-var brandCounts = {{ brand_counts|default({})|tojson }};
+var prefixMaxNums = {{ prefix_max_nums|default({})|tojson }};
 
 function metaSelectChanged(sel, inputId) {
   var input = document.getElementById(inputId);
@@ -109,25 +115,30 @@ function metaSelectChanged(sel, inputId) {
     input.style.display = 'none';
     input.value = sel.value;
   }
-  if (inputId === 'brand') updateLabelPreview();
+  if (inputId === 'brand' || inputId === 'size') updateLabelPreview();
 }
 
 function updateLabelPreview() {
   var brand = document.getElementById('brand').value.trim();
+  var size  = document.getElementById('size').value.trim();
+  var includeSize = document.getElementById('include_size_in_label').checked;
   var count = parseInt(document.getElementById('count').value, 10) || 1;
   var preview = document.getElementById('label-preview');
   if (!brand) { preview.textContent = ''; return; }
-  var existing = brandCounts[brand] !== undefined ? brandCounts[brand] : 0;
+  var prefix = (includeSize && size) ? brand + ' ' + size : brand;
+  var existing = prefixMaxNums[prefix] !== undefined ? prefixMaxNums[prefix] : 0;
   var first = existing + 1;
   var last  = existing + count;
   var pad = function(n) { return n.toString().padStart(3, '0'); };
   preview.textContent = count === 1
-    ? 'Will create: ' + brand + ' ' + pad(first)
-    : 'Will create: ' + brand + ' ' + pad(first) + ' \u2192 ' + brand + ' ' + pad(last);
+    ? 'Will create: ' + prefix + ' ' + pad(first)
+    : 'Will create: ' + prefix + ' ' + pad(first) + ' \u2192 ' + prefix + ' ' + pad(last);
 }
 
 document.getElementById('count').addEventListener('input', updateLabelPreview);
 document.getElementById('brand').addEventListener('input', updateLabelPreview);
+document.getElementById('size').addEventListener('input', updateLabelPreview);
+document.getElementById('include_size_in_label').addEventListener('change', updateLabelPreview);
 
 // Restore brand state on error re-render
 (function () {
diff --git a/tests/test_acceptance.py b/tests/test_acceptance.py
index f21e394..b21c9ba 100644
--- a/tests/test_acceptance.py
+++ b/tests/test_acceptance.py
@@ -48,7 +48,7 @@ def test_dashboard_loads(seeded_client):
 def test_battery_add_get_renders(client):
     resp = client.get("/battery/add")
     assert resp.status_code == 200
-    assert b"brandCounts" in resp.data
+    assert b"prefixMaxNums" in resp.data
 
 
 def test_battery_add_brand_counts_reflects_existing(seeded_client):