diff --git a/vlib/runtime/used_memory_darwin.c.v b/vlib/runtime/used_memory_darwin.c.v
new file mode 100644
index 0000000000..5a20cf3fd0
--- /dev/null
+++ b/vlib/runtime/used_memory_darwin.c.v
@@ -0,0 +1,17 @@
+module runtime
+
+struct C.task_basic_info {
+	resident_size u64
+}
+
+fn C.task_info(C.task_t, int, &C.task_basic_info, &u64) int
+
+// used_memory retrieves the current physical memory usage of the process.
+pub fn used_memory() !u64 {
+	mut info := C.task_basic_info{}
+	mut count := u64(C.MACH_TASK_BASIC_INFO_COUNT)
+	if C.task_info(C.mach_task_self(), C.TASK_BASIC_INFO, &info, &count) == C.KERN_SUCCESS {
+		return info.resident_size
+	}
+	return 0
+}
diff --git a/vlib/runtime/used_memory_default.c.v b/vlib/runtime/used_memory_default.c.v
new file mode 100644
index 0000000000..baada77895
--- /dev/null
+++ b/vlib/runtime/used_memory_default.c.v
@@ -0,0 +1,6 @@
+module runtime
+
+// used_memory retrieves the current physical memory usage of the process.
+pub fn used_memory() !u64 {
+	return error('`used_memory()` not implemented')
+}
diff --git a/vlib/runtime/used_memory_linux.c.v b/vlib/runtime/used_memory_linux.c.v
new file mode 100644
index 0000000000..19b5a5d92f
--- /dev/null
+++ b/vlib/runtime/used_memory_linux.c.v
@@ -0,0 +1,19 @@
+module runtime
+
+import os
+
+// used_memory retrieves the current physical memory usage of the process.
+pub fn used_memory() !u64 {
+	file := '/proc/self/status'
+	content := os.read_file(file) or { return 0 }
+	for line in content.split_into_lines() {
+		if line.starts_with('VmRSS:') {
+			parts := line.split(':')
+			if parts.len > 1 {
+				value := parts[1].trim_space().replace('kB', '').trim_space()
+				return value.u64() * 1024 // Convert to bytes
+			}
+		}
+	}
+	return 0
+}
diff --git a/vlib/runtime/used_memory_test.v b/vlib/runtime/used_memory_test.v
new file mode 100644
index 0000000000..24580fdf40
--- /dev/null
+++ b/vlib/runtime/used_memory_test.v
@@ -0,0 +1,21 @@
+import runtime
+
+fn test_used_memory() {
+	used1 := runtime.used_memory()!
+	println('used memory 1 : ${used1}')
+
+	mut mem1 := unsafe { malloc(4096 * 1024) }
+	unsafe { vmemset(mem1, 1, 4096 * 1024) }
+
+	used2 := runtime.used_memory()!
+	println('used memory 2 : ${used2}')
+
+	mut mem2 := unsafe { malloc(8192 * 1024) }
+	unsafe { vmemset(mem2, 1, 8192 * 1024) }
+
+	used3 := runtime.used_memory()!
+	println('used memory 3 : ${used3}')
+	assert used1 > 0
+	assert used2 > used1
+	assert used3 > used2
+}
diff --git a/vlib/runtime/used_memory_windows.c.v b/vlib/runtime/used_memory_windows.c.v
new file mode 100644
index 0000000000..6aa9113edc
--- /dev/null
+++ b/vlib/runtime/used_memory_windows.c.v
@@ -0,0 +1,22 @@
+module runtime
+
+#flag -lpsapi
+#include <psapi.h>
+
+@[typedef]
+struct C.PROCESS_MEMORY_COUNTERS {
+	cb             u64
+	WorkingSetSize isize
+}
+
+fn C.GetProcessMemoryInfo(int, &C.PROCESS_MEMORY_COUNTERS, u64) bool
+
+// used_memory retrieves the current physical memory usage of the process.
+pub fn used_memory() !u64 {
+	mut pmc := C.PROCESS_MEMORY_COUNTERS{}
+	pmc.cb = u64(sizeof(pmc))
+	if C.GetProcessMemoryInfo(C.GetCurrentProcess(), &pmc, pmc.cb) {
+		return u64(pmc.WorkingSetSize)
+	}
+	return 0
+}