Question : Problem: VPN frame size

We have two sites connected over the internet , with an IPSEC vpn. There are ASAs on either side. The mtu has been hardcoded to 1500.  

Is this bad?  How much header size does IPSEC add to an ethernet frame? If regular ethernet frames are around 1518, what size are they after ipsec encapsulation?

thanks

Answer : Problem: VPN frame size

The best thing I've found is to adjust the maximum segment size to about 1350.  It's a trade-off of slightly higher overhead, but much less work to find the "perfect" value.