diff --git a/access_log.json b/access_log.json
index 802f232..9b2c57f 100644
--- a/access_log.json
+++ b/access_log.json
@@ -656,5 +656,12 @@
     "endpoint": "/",
     "method": "GET",
     "status": 200
+  },
+  {
+    "timestamp": "2026-07-07T16:41:46.568545",
+    "username": "mtazl",
+    "endpoint": "/",
+    "method": "GET",
+    "status": 200
   }
 ]
\ No newline at end of file
diff --git a/build_info.json b/build_info.json
index 62b9140..c6a437c 100644
--- a/build_info.json
+++ b/build_info.json
@@ -1,6 +1,6 @@
 {
   "version": "v0.4-dev",
   "branch": "develop/v0.4",
-  "commit": "4670666",
-  "timestamp": "2026-07-07T16:39:21+02:00"
+  "commit": "7a27fb8",
+  "timestamp": "2026-07-07T16:46:32+02:00"
 }
diff --git a/templates/roll_calculator.html b/templates/roll_calculator.html
index 9e1e1f1..b38ddc1 100644
--- a/templates/roll_calculator.html
+++ b/templates/roll_calculator.html
@@ -575,6 +575,13 @@
                 <span class="unit-label">kg</span>
               </div>
             </div>
+            <div class="form-group">
+              <label>Max. Roll Diameter</label>
+              <div class="input-with-unit">
+                <input type="number" id="d-target-di" placeholder="mm" min="0" step="1">
+                <span class="unit-label">mm</span>
+              </div>
+            </div>
             <div class="form-group">
               <label>Max. Roll Weight</label>
               <div class="input-with-unit">
@@ -1014,14 +1021,14 @@ document.getElementById('d-calc').addEventListener('click', () => {
     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 D_target = parseFloat(document.getElementById('d-target-di').value) || 0;
 
     if (!d || !t || !D_target || !wi || !aw || !maxWeight) {
-      alert('Please enter d, t, max. diameter, roll width, area weight, and max. roll weight.');
+      alert('Please enter d, t, max. roll diameter, roll width, area weight, and max. roll weight.');
       return;
     }
     if (D_target <= d) {
-      alert('Target diameter must be larger than core diameter.');
+      alert('Max. roll diameter must be larger than core diameter.');
       return;
     }
 
@@ -1055,7 +1062,7 @@ document.getElementById('d-calc').addEventListener('click', () => {
     }
 
     resRange.innerHTML =
-      '<div>Resulting diameter: ' + D_result.toFixed(1) + ' mm</div>' +
+      '<div>Resulting Roll 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>' +
@@ -1064,7 +1071,6 @@ document.getElementById('d-calc').addEventListener('click', () => {
       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);
   }
 
@@ -1083,7 +1089,7 @@ 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', 'd-max-weight', 'd-min-le'].forEach(id => {
+  ['d-co', 'd-th', 'd-tol', 'd-le', 'd-di', 'd-wi', 'd-aw', 'd-wo', 'd-target-di', 'd-max-weight', 'd-min-le'].forEach(id => {
     const el = document.getElementById(id);
     if (el) el.value = id === 'd-co' ? '150' : '';
   });