diff --git a/backend/provisioner.py b/backend/provisioner.py
index 9e84c2f..a9a1c44 100644
--- a/backend/provisioner.py
+++ b/backend/provisioner.py
@@ -300,16 +300,8 @@ def _process_job(job_id: str, req: JobSubmissionRequest):
 
             target_gb = req.target_disk_size_gb
             if target_gb is None:
-                # Auto-shrink: 10% of virtual size, minimum 20 GB
-                auto_target = max(int(current_gb * 0.1), 20)
-                if current_gb > auto_target:
-                    target_gb = auto_target
-                    logger.info("Auto-shrink: %.1f GiB → %d GiB (10%% rule)", current_gb, target_gb)
-                else:
-                    target_gb = int(round(current_gb)) + 1
-                    logger.info("Disk already <= target, no shrink needed")
-
-            if target_gb < current_gb:
+                logger.info("Disk size not specified — keeping current (%.1f GiB)", current_gb)
+            elif target_gb < current_gb:
                 _update_job(job_id, progress=60,
                             message=f"Shrinking disk to {target_gb} GiB...")
                 logger.info("Shrinking disk: %.1f GiB → %d GiB via virt-resize", current_gb, target_gb)
diff --git a/frontend/templates/_analysis.html b/frontend/templates/_analysis.html
index 4646fe5..97e7013 100644
--- a/frontend/templates/_analysis.html
+++ b/frontend/templates/_analysis.html
@@ -66,13 +66,15 @@
       </div>
       <div class="pve-form-group">
         <label>Target Disk Size (GB)</label>
-        <input type="number" name="target_disk_size_gb" class="pve-input"
-               value="{{ analysis.disk_size_gb }}"
-               placeholder="Leave blank for auto-shrink">
-        <span class="pve-hint">
-          {{ analysis.disk_size_gb }} GB detected. Auto-shrink to {{ (analysis.disk_size_gb * 0.1)|round(0)|int if (analysis.disk_size_gb * 0.1) > 20 else 20 }} GB if left blank.<br>
+        <input type="number" name="target_disk_size_gb" id="target-disk-size" class="pve-input"
+               value="{{ analysis.disk_size_gb }}" disabled>
+        <label style="margin-top:0.3rem;font-size:0.72rem;display:flex;align-items:center;gap:0.3rem;cursor:pointer;">
+          <input type="checkbox" id="enable-resize" onchange="toggleDiskResize()">
+          Enable disk resize (shrink or expand)
+        </label>
+        <span class="pve-hint" id="resize-hint">
+          Default: {{ analysis.disk_size_gb }} GB (no resize). Check the box above to change.
           <strong>Warning:</strong> shrinking can break complex layouts (LVM, encryption).
-          If unsure, enter the full size ({{ analysis.disk_size_gb }} GB) to skip.
         </span>
       </div>
     </div>
diff --git a/frontend/templates/index.html b/frontend/templates/index.html
index 97c331e..08e8874 100644
--- a/frontend/templates/index.html
+++ b/frontend/templates/index.html
@@ -166,6 +166,18 @@ function showError(msg) {
   if (el) el.innerHTML += '<div class="pve-alert pve-alert-error" style="margin-top:0.5rem;">' + msg + '</div>';
 }
 
+function toggleDiskResize() {
+  var cb = document.getElementById('enable-resize');
+  var inp = document.getElementById('target-disk-size');
+  if (!cb || !inp) return;
+  if (cb.checked) {
+    inp.removeAttribute('disabled');
+    inp.focus();
+  } else {
+    inp.setAttribute('disabled', '');
+  }
+}
+
 function sleep(ms) { return new Promise(resolve => setTimeout(resolve, ms)); }
 
 async function startSession(e) {