diff --git a/Frequently-Asked-Questions.md b/Frequently-Asked-Questions.md
index 9cc2306..9fbf487 100644
--- a/Frequently-Asked-Questions.md
+++ b/Frequently-Asked-Questions.md
@@ -35,3 +35,13 @@ There are two device types TUN and TAP and the only difference between them is t
 All the rest is about how VpnCloud decides where packets/frames should be sent to. In routed mode each node claims one or more address regions by prefix and all the nodes match against those prefixes. In switch mode, nodes learn addresses by looking at the source addresses and broadcast for unknown addresses. Routed mode is native to TUN devices and switched mode is native to TAP devices but there is no reason not to use switched mode for TUN devices. 
 
 ([Full thread in #12](../issues/12))
+
+
+#### How much overhead do VpnCloud headers add?
+
+VpnCloud has a fixed 8-byte header. If encryption is used, another 12-byte header is added. As VpnCloud packets are transported over UDP, you have to add the UDP header (8 bytes), an IP header (20 bytes for IPv4 and 40 bytes for IPv6) and an Ethernet header (14 bytes). 
+
+So the total overhead is:
+- 50 bytes if unencrypted and IPv4
+- plus 12 bytes for encryption
+- plus 20 bytes for IPv6