diff --git a/kvmstats.sh b/kvmstats.sh
index 7301962..bf8d06c 100644
--- a/kvmstats.sh
+++ b/kvmstats.sh
@@ -1,5 +1,35 @@
 #!/bin/sh
 
+usage () {
+	echo 'usage: kvmstats.sh [-u M|G]'
+	exit 1
+}
+
+POW=$(echo 1024 ^ 1 | bc)
+while echo $1 | grep -q '^-[[:alnum:]]'
+do
+	case $1 in
+	'-u')
+		case $2 in
+		'M')
+			POW=$(echo 1024 ^ 2 | bc)
+			;;
+		'G')
+			POW=$(echo 1024 ^ 3 | bc)
+			;;
+		*)
+			usage
+		esac
+		;;
+	*)
+		usage
+	esac
+	shift
+done
+
+# since libvirt seems to store memoy in KiB, POW must be lowered by 1
+POW=$(expr $POW / 1024)
+
 for DEP in hxselect lvs tempfile
 do
 	if [ -z "$(which $DEP)" ]
@@ -14,7 +44,7 @@ TMPFILE=$(tempfile)
 for VM in $(virsh list --all --name)
 do
     VCPU=$(hxselect -c 'domain vcpu' </etc/libvirt/qemu/$VM.xml)
-    RAM=$(hxselect -c 'domain memory' </etc/libvirt/qemu/$VM.xml)
+    RAM=$(expr $(hxselect -c 'domain memory' </etc/libvirt/qemu/$VM.xml) / $POW)
     for DEV in $(hxselect -s'\n' 'domain devices disk[device=disk] source' </etc/libvirt/qemu/$VM.xml | cut -d\" -f2)
     do
         case $DEV in