diff --git a/src/core/lib/IP.mjs b/src/core/lib/IP.mjs
index c97f87ab..41bada93 100644
--- a/src/core/lib/IP.mjs
+++ b/src/core/lib/IP.mjs
@@ -189,6 +189,55 @@ export function ipv6HyphenatedRange(range, includeNetworkInfo) {
     return output;
 }
 
+/**
+ * Parses an IPv4 subnet mask (e.g. 192.168.0.0/255.255.255.0) and displays information about it.
+ *
+ * @param {RegExp} subnetMask
+ * @param {boolean} includeNetworkInfo
+ * @param {boolean} enumerateAddresses
+ * @param {boolean} allowLargeList
+ * @returns {string}
+ */
+export function ipv4SubnetMask(subnetMask, includeNetworkInfo, enumerateAddresses, allowLargeList) {
+    const network = strToIpv4(subnetMask[1]),
+        mask = subnetMask[2];
+    let output = "";
+
+    // Calculate the CIDR
+    const octets = mask.split(".").map(Number);
+    let cidr = 0;
+    for (let i = 0; i < octets.length; i++) {
+        let octet = octets[i];
+        while (octet) {
+            cidr += (octet & 1);  // Check if the last bit is 1
+            octet >>= 1;          // Shift bits to the right
+        }
+    }
+    if (cidr < 0 || cidr > 31) {
+        throw new OperationError("IPv4 CIDR must be less than 32");
+    }
+
+    const ip1 = network & strToIpv4(mask),
+        ip2 = ip1 | ~strToIpv4(mask);
+
+    if (includeNetworkInfo) {
+        output += "Network: " + ipv4ToStr(network) + "\n";
+        output += "CIDR: " + cidr + "\n";
+        output += "Mask: " + mask + "\n";
+        output += "Range: " + ipv4ToStr(ip1) + " - " + ipv4ToStr(ip2) + "\n";
+        output += "Total addresses in range: " + (((ip2 - ip1) >>> 0) + 1) + "\n\n";
+    }
+
+    if (enumerateAddresses) {
+        if (cidr >= 16 || allowLargeList) {
+            output += generateIpv4Range(ip1, ip2).join("\n");
+        } else {
+            output += _LARGE_RANGE_ERROR;
+        }
+    }
+    return output;
+}
+
 /**
  * Parses a list of IPv4 addresses separated by a new line (\n) and displays information
  * about it.
diff --git a/src/core/operations/ParseIPRange.mjs b/src/core/operations/ParseIPRange.mjs
index 2c59c015..5a2496e3 100644
--- a/src/core/operations/ParseIPRange.mjs
+++ b/src/core/operations/ParseIPRange.mjs
@@ -7,7 +7,7 @@
 
 import Operation from "../Operation.mjs";
 import OperationError from "../errors/OperationError.mjs";
-import {ipv4CidrRange, ipv4HyphenatedRange, ipv4ListedRange, ipv6CidrRange, ipv6HyphenatedRange, ipv6ListedRange} from "../lib/IP.mjs";
+import {ipv4CidrRange, ipv4HyphenatedRange, ipv4SubnetMask, ipv4ListedRange, ipv6CidrRange, ipv6HyphenatedRange, ipv6ListedRange} from "../lib/IP.mjs";
 
 /**
  * Parse IP range operation
@@ -60,6 +60,7 @@ class ParseIPRange extends Operation {
         // Check what type of input we are looking at
         const ipv4CidrRegex = /^\s*((?:\d{1,3}\.){3}\d{1,3})\/(\d\d?)\s*$/,
             ipv4RangeRegex = /^\s*((?:\d{1,3}\.){3}\d{1,3})\s*-\s*((?:\d{1,3}\.){3}\d{1,3})\s*$/,
+            ipv4SubnetMaskRegex = /^\s*((?:\d{1,3}\.){3}\d{1,3})\/((?:\d{1,3}\.){3}\d{1,3})\s*$/,
             ipv4ListRegex = /^\s*(((?:\d{1,3}\.){3}\d{1,3})(\/(\d\d?))?(\n|$)(\n*))+\s*$/,
             ipv6CidrRegex = /^\s*(((?=.*::)(?!.*::.+::)(::)?([\dA-F]{1,4}:(:|\b)|){5}|([\dA-F]{1,4}:){6})((([\dA-F]{1,4}((?!\4)::|:\b|(?![\dA-F])))|(?!\3\4)){2}|(((2[0-4]|1\d|[1-9])?\d|25[0-5])\.?\b){4}))\/(\d\d?\d?)\s*$/i,
             ipv6RangeRegex = /^\s*(((?=.*::)(?!.*::[^-]+::)(::)?([\dA-F]{1,4}:(:|\b)|){5}|([\dA-F]{1,4}:){6})((([\dA-F]{1,4}((?!\4)::|:\b|(?![\dA-F])))|(?!\3\4)){2}|(((2[0-4]|1\d|[1-9])?\d|25[0-5])\.?\b){4}))\s*-\s*(((?=.*::)(?!.*::.+::)(::)?([\dA-F]{1,4}:(:|\b)|){5}|([\dA-F]{1,4}:){6})((([\dA-F]{1,4}((?!\17)::|:\b|(?![\dA-F])))|(?!\16\17)){2}|(((2[0-4]|1\d|[1-9])?\d|25[0-5])\.?\b){4}))\s*$/i,
@@ -70,6 +71,8 @@ class ParseIPRange extends Operation {
             return ipv4CidrRange(match, includeNetworkInfo, enumerateAddresses, allowLargeList);
         } else if ((match = ipv4RangeRegex.exec(input))) {
             return ipv4HyphenatedRange(match, includeNetworkInfo, enumerateAddresses, allowLargeList);
+        } else if ((match = ipv4SubnetMaskRegex.exec(input))) {
+            return ipv4SubnetMask(match, includeNetworkInfo, enumerateAddresses, allowLargeList);
         } else if ((match = ipv4ListRegex.exec(input))) {
             return ipv4ListedRange(match, includeNetworkInfo, enumerateAddresses, allowLargeList);
         } else if ((match = ipv6CidrRegex.exec(input))) {