diff --git a/script.js b/script.js
index 1485e9f..26e8293 100644
--- a/script.js
+++ b/script.js
@@ -2973,52 +2973,100 @@ let ipamData = [];
 let ipamExpandedIds = new Set();
 let ipamDrillStack = []; // [{id, label}] breadcrumb
 
-// --- IP-laskenta-apufunktiot ---
-function ipToInt(ip) {
-    return ip.split('.').reduce((acc, oct) => (acc << 8) + parseInt(oct), 0) >>> 0;
+// --- IP-laskenta-apufunktiot (IPv4 + IPv6) ---
+function ipv4ToBI(ip) {
+    return ip.split('.').reduce((acc, oct) => (acc << 8n) + BigInt(parseInt(oct)), 0n);
 }
-function prefixToMask(prefix) {
-    return prefix === 0 ? 0 : (~0 << (32 - prefix)) >>> 0;
+function ipv6ToBI(ip) {
+    // Expand :: shorthand
+    let parts = ip.split('::');
+    let left = parts[0] ? parts[0].split(':') : [];
+    let right = parts.length > 1 && parts[1] ? parts[1].split(':') : [];
+    const missing = 8 - left.length - right.length;
+    const full = [...left, ...Array(missing).fill('0'), ...right];
+    return full.reduce((acc, hex) => (acc << 16n) + BigInt(parseInt(hex || '0', 16)), 0n);
 }
 function parseNetwork(verkko) {
     if (!verkko) return null;
     const v = verkko.trim();
+    let ip, prefix;
     if (v.includes('/')) {
-        const [ip, pfx] = v.split('/');
-        const prefix = parseInt(pfx);
-        if (isNaN(prefix) || prefix < 0 || prefix > 32) return null;
-        const parts = ip.split('.');
-        if (parts.length !== 4) return null;
-        return { net: ipToInt(ip), prefix };
+        const slash = v.lastIndexOf('/');
+        ip = v.substring(0, slash);
+        prefix = parseInt(v.substring(slash + 1));
+        if (isNaN(prefix) || prefix < 0) return null;
     } else {
-        const parts = v.split('.');
-        if (parts.length !== 4) return null;
-        return { net: ipToInt(v), prefix: 32 };
+        ip = v;
+        prefix = null; // auto-detect
     }
+    // IPv6?
+    if (ip.includes(':')) {
+        const maxBits = 128;
+        if (prefix === null) prefix = 128;
+        if (prefix > maxBits) return null;
+        try {
+            return { net: ipv6ToBI(ip), prefix, bits: maxBits, v6: true };
+        } catch { return null; }
+    }
+    // IPv4
+    const parts = ip.split('.');
+    if (parts.length !== 4) return null;
+    const maxBits = 32;
+    if (prefix === null) prefix = 32;
+    if (prefix > maxBits) return null;
+    return { net: ipv4ToBI(ip), prefix, bits: maxBits, v6: false };
 }
-function isSubnetOf(childNet, childPrefix, parentNet, parentPrefix) {
+function isSubnetOf(childNet, childPrefix, childBits, parentNet, parentPrefix, parentBits) {
+    if (childBits !== parentBits) return false; // eri perhe (v4 vs v6)
     if (childPrefix <= parentPrefix) return false;
-    const mask = prefixToMask(parentPrefix);
-    return (childNet & mask) === (parentNet & mask);
+    const shift = BigInt(parentBits - parentPrefix);
+    return (childNet >> shift) === (parentNet >> shift);
+}
+// Laske subnetin käyttöaste: kuinka monta lasta (direct children) vs kapasiteetti
+function subnetUsageHtml(node) {
+    if (node.entry.tyyppi !== 'subnet' || node.children.length === 0) return '';
+    const childCount = node.children.length;
+    // Laske kuinka monta "slottia" tässä subnetissa on seuraavalla tasolla
+    // Etsi yleisin lapsi-prefix
+    const childPrefixes = node.children.filter(c => c.prefix > node.prefix).map(c => c.prefix);
+    if (childPrefixes.length === 0) return `<span class="ipam-usage">${childCount}</span>`;
+    // Käytä pienintä child-prefixiä (isoimpia aliverkkoja) kapasiteetin laskuun
+    const commonPrefix = Math.min(...childPrefixes);
+    const bits = node.entry.tyyppi === 'subnet' ? (node.children[0]?.bits || 32) : 32;
+    const slotBits = commonPrefix - node.prefix;
+    if (slotBits <= 0 || slotBits > 20) return `<span class="ipam-usage">${childCount}</span>`;
+    const totalSlots = 1 << slotBits; // 2^slotBits
+    const sameLevel = node.children.filter(c => c.prefix === commonPrefix).length;
+    const freeSlots = totalSlots - sameLevel;
+    return `<span class="ipam-usage" title="${sameLevel}/${totalSlots} /${commonPrefix} käytössä">${sameLevel}/${totalSlots}</span>`;
 }
 
 // --- Puurakenne ---
 function buildIpamTree(entries) {
-    // Parsitaan verkko-osoitteet ja suodatetaan validit
-    const items = entries.map(e => {
+    // Parsitaan verkko-osoitteet; ei-parsittavat lisätään juureen sellaisenaan
+    const unparsed = [];
+    const items = [];
+    for (const e of entries) {
         const parsed = parseNetwork(e.verkko);
-        return parsed ? { entry: e, net: parsed.net, prefix: parsed.prefix, children: [] } : null;
-    }).filter(Boolean);
-    // Järjestetään: pienin prefix (isoin verkko) ensin, sitten IP-osoitteen mukaan
-    items.sort((a, b) => a.prefix - b.prefix || a.net - b.net);
+        if (parsed) {
+            items.push({ entry: e, net: parsed.net, prefix: parsed.prefix, bits: parsed.bits, v6: parsed.v6, children: [] });
+        } else {
+            unparsed.push({ entry: e, net: 0n, prefix: 0, bits: 0, v6: false, children: [] });
+        }
+    }
+    // Järjestetään: v4 ennen v6, pienin prefix ensin, sitten osoitteen mukaan
+    items.sort((a, b) => {
+        if (a.v6 !== b.v6) return a.v6 ? 1 : -1;
+        if (a.prefix !== b.prefix) return a.prefix - b.prefix;
+        return a.net < b.net ? -1 : a.net > b.net ? 1 : 0;
+    });
     const roots = [];
     for (const item of items) {
-        let placed = false;
         // Etsi lähin parent (suurin prefix joka sisältää tämän)
         const findParent = (nodes) => {
             for (let i = nodes.length - 1; i >= 0; i--) {
                 const node = nodes[i];
-                if (isSubnetOf(item.net, item.prefix, node.net, node.prefix)) {
+                if (isSubnetOf(item.net, item.prefix, item.bits, node.net, node.prefix, node.bits)) {
                     // Tarkista ensin onko jokin lapsi tarkempi parent
                     if (!findParent(node.children)) {
                         node.children.push(item);
@@ -3032,6 +3080,8 @@ function buildIpamTree(entries) {
             roots.push(item);
         }
     }
+    // Lisää ei-parsittavat (esim. virheelliset osoitteet) juureen
+    roots.push(...unparsed);
     return roots;
 }
 
@@ -3057,7 +3107,7 @@ function flattenTree(nodes, depth, drillId) {
         for (const node of list) {
             const hasChildren = node.children.length > 0;
             const expanded = ipamExpandedIds.has(node.entry.id);
-            rows.push({ entry: node.entry, depth: d, hasChildren, expanded });
+            rows.push({ entry: node.entry, depth: d, hasChildren, expanded, node });
             if (hasChildren && expanded) {
                 render(node.children, d + 1);
             }
@@ -3140,7 +3190,7 @@ function renderIpam() {
                 <td style="padding-left:${indent}rem;white-space:nowrap;">
                     ${toggleIcon}${typeTag}
                 </td>
-                <td><code class="ipam-network">${esc(e.verkko || '-')}</code>${drillBtn}</td>
+                <td><code class="ipam-network">${esc(e.verkko || '-')}</code>${drillBtn} ${subnetUsageHtml(r.node)}</td>
                 <td>${esc(e.nimi || '-')}</td>
                 <td>${vlanRefHtml(e.vlan_id)}</td>
                 <td>${e.site_name ? esc(e.site_name) : '<span style="color:#ccc;">—</span>'}</td>
diff --git a/style.css b/style.css
index 9e7f6fa..0a78ca5 100644
--- a/style.css
+++ b/style.css
@@ -1089,6 +1089,7 @@ span.empty {
 .ipam-bc-link:hover { text-decoration:underline; }
 .ipam-bc-current { color:#333; font-weight:600; cursor:default; }
 .ipam-bc-current:hover { text-decoration:none; }
+.ipam-usage { display:inline-block; margin-left:0.5rem; padding:1px 6px; border-radius:8px; font-size:0.72rem; font-weight:600; background:#f0f4ff; color:#4338ca; }
 
 /* Role badge */
 .role-badge {