diff --git a/access_log.json b/access_log.json
index 2c39a17..802f232 100644
--- a/access_log.json
+++ b/access_log.json
@@ -642,5 +642,19 @@
     "endpoint": "/",
     "method": "GET",
     "status": 200
+  },
+  {
+    "timestamp": "2026-07-07T16:34:58.280178",
+    "username": "mtazl",
+    "endpoint": "/",
+    "method": "GET",
+    "status": 200
+  },
+  {
+    "timestamp": "2026-07-07T16:36:56.896657",
+    "username": "mtazl",
+    "endpoint": "/",
+    "method": "GET",
+    "status": 200
   }
 ]
\ No newline at end of file
diff --git a/build_info.json b/build_info.json
index 213cbe8..62b9140 100644
--- a/build_info.json
+++ b/build_info.json
@@ -1,6 +1,6 @@
 {
-  "version": "0.4",
+  "version": "v0.4-dev",
   "branch": "develop/v0.4",
-  "commit": "ffa3481",
-  "timestamp": "2026-07-07T10:26:13Z"
+  "commit": "4670666",
+  "timestamp": "2026-07-07T16:39:21+02:00"
 }
diff --git a/templates/roll_calculator.html b/templates/roll_calculator.html
index e67b01c..9e1e1f1 100644
--- a/templates/roll_calculator.html
+++ b/templates/roll_calculator.html
@@ -48,6 +48,9 @@
     .result-label { font-size: 12px; color: #1F5438; font-weight: 600; text-transform: uppercase; }
     .result-value { font-size: 28px; font-weight: 700; color: #1F5438; line-height: 1.2; }
     .result-range { font-size: 12px; color: #1F5438; margin-top: 4px; font-weight: 500; }
+    .result-range div { margin-top: 2px; }
+    .result-range .range-warning { color: #9a6700; font-weight: 700; }
+    .result-range .range-ok { color: #1F5438; font-weight: 700; }
     .forklift-check { border-radius: 7px; padding: 14px 16px; margin-top: 14px; font-size: 13px; line-height: 1.6; display: none; }
     .forklift-check.show { display: block; }
     .forklift-check.fc-ok { background: #eafaf1; border: 1.5px solid #28a745; }
@@ -572,6 +575,20 @@
                 <span class="unit-label">kg</span>
               </div>
             </div>
+            <div class="form-group">
+              <label>Max. Roll Weight</label>
+              <div class="input-with-unit">
+                <input type="number" id="d-max-weight" placeholder="kg" min="0" step="1">
+                <span class="unit-label">kg</span>
+              </div>
+            </div>
+            <div class="form-group">
+              <label>Minimum Product Length</label>
+              <div class="input-with-unit">
+                <input type="number" id="d-min-le" placeholder="m" min="0" step="0.1">
+                <span class="unit-label">m</span>
+              </div>
+            </div>
           </div>
         </div>
 
@@ -993,13 +1010,62 @@ document.getElementById('d-calc').addEventListener('click', () => {
     resRange.textContent = '';
     document.getElementById('d-le').value = L_calc.toFixed(2);
   } else if (mode === 'target') {
-    if (!d || !t) { alert('Please enter d and t.'); return; }
+    const wi = parseFloat(document.getElementById('d-wi').value) || 0;
+    const aw = parseFloat(document.getElementById('d-aw').value) || 0;
+    const maxWeight = parseFloat(document.getElementById('d-max-weight').value) || 0;
+    const minLength = parseFloat(document.getElementById('d-min-le').value) || 0;
     const D_target = D || 800;
-    const L_calc = (Math.PI / (4 * t)) * (D_target*D_target - d*d) / 1000;
-    resLabel.textContent = 'Length for Target Diameter ' + D_target + ' mm';
-    resVal.textContent = L_calc.toFixed(2) + ' m';
-    resRange.textContent = '';
-    document.getElementById('d-le').value = L_calc.toFixed(2);
+
+    if (!d || !t || !D_target || !wi || !aw || !maxWeight) {
+      alert('Please enter d, t, max. diameter, roll width, area weight, and max. roll weight.');
+      return;
+    }
+    if (D_target <= d) {
+      alert('Target diameter must be larger than core diameter.');
+      return;
+    }
+
+    const L_diameter = (Math.PI / (4 * t)) * (D_target*D_target - d*d) / 1000;
+    const L_weight = maxWeight * 1000 / (aw * wi);
+    const L_allowed = Math.min(L_diameter, L_weight);
+    const D_result = Math.sqrt(d*d + (4*L_allowed*1000*t)/Math.PI);
+    const W_result = aw * L_allowed * wi / 1000;
+    const diameterUtil = D_result / D_target * 100;
+    const weightUtil = W_result / maxWeight * 100;
+    const lengthDiff = minLength > 0 ? L_allowed - minLength : null;
+    const epsilon = 0.0001;
+    let limitingFactor = 'Diameter + Weight';
+
+    if (L_diameter < L_weight - epsilon) {
+      limitingFactor = 'Diameter';
+    } else if (L_weight < L_diameter - epsilon) {
+      limitingFactor = 'Weight';
+    }
+
+    resLabel.textContent = 'Maximum Allowed Product Length';
+    resVal.textContent = L_allowed.toFixed(2) + ' m';
+
+    const minLengthText = minLength > 0 ? minLength.toFixed(2) + ' m' : 'not set';
+    const diffText = lengthDiff !== null ? lengthDiff.toFixed(2) + ' m' : 'n/a';
+    let minStatus = '<div>Minimum length not set</div>';
+    if (minLength > 0 && L_allowed < minLength) {
+      minStatus = '<div class="range-warning">Warning: maximum allowed length is below the minimum product length.</div>';
+    } else if (minLength > 0) {
+      minStatus = '<div class="range-ok">Minimum length OK</div>';
+    }
+
+    resRange.innerHTML =
+      '<div>Resulting diameter: ' + D_result.toFixed(1) + ' mm</div>' +
+      '<div>Resulting weight: ' + W_result.toFixed(1) + ' kg</div>' +
+      '<div>Minimum length: ' + minLengthText + '</div>' +
+      '<div>Difference: ' + diffText + '</div>' +
+      '<div>Limiting factor: ' + limitingFactor + '</div>' +
+      '<div>Utilization: Diameter ' + diameterUtil.toFixed(1) + '% | Weight ' + weightUtil.toFixed(1) + '%</div>' +
+      minStatus;
+
+    document.getElementById('d-le').value = L_allowed.toFixed(2);
+    document.getElementById('d-di').value = D_result.toFixed(1);
+    document.getElementById('d-wo').value = W_result.toFixed(1);
   }
 
   const wi = parseFloat(document.getElementById('d-wi').value) || 0;
@@ -1017,7 +1083,7 @@ document.getElementById('d-calc').addEventListener('click', () => {
 });
 
 document.getElementById('d-reset').addEventListener('click', () => {
-  ['d-co', 'd-th', 'd-tol', 'd-le', 'd-di', 'd-wi', 'd-aw', 'd-wo'].forEach(id => {
+  ['d-co', 'd-th', 'd-tol', 'd-le', 'd-di', 'd-wi', 'd-aw', 'd-wo', 'd-max-weight', 'd-min-le'].forEach(id => {
     const el = document.getElementById(id);
     if (el) el.value = id === 'd-co' ? '150' : '';
   });