If we:
1) Count bytes/bits at the network adapter level (raw # of bits through the NIC) and,
2) Count bytes in all HTTP/S request/responses.
Assuming only HTTP/S traffic is on the box, and assuming a statistically relevant amount of "typical" web traffic:
I want to know about how much more traffic will be counted at the NIC level than at the HTTP/S level (counting http headers and all) because of the extra network overhead.
You have zero knowledge about the layers below HTTP. You can't even assume the HTTP request will be delivered over TCP/IP. Even if it is, you have zero knowledge about the overhead added by the network layer. Or what the reliability of the route will be and what overhead will be due to dropped/resent packets.
Update: Based on your comment, here are some back-of-the-napkin estimates:
The maximum segment size (which does not include the TCP or IP headers) is typically negotiated between the layers to the size of the MTU minus the headers size. For Ethernet MTU is usually configured at 1500 bytes. The TCP header is 160 bits, or 20 bytes. The fixed part of the IPv4 header is 160 bits, or 20 bytes as well. The fixed part of the IPv6 header is 320 bits, or 40 bytes. Thus:
overhead = TCP + IP = 40 bytes
payload = 1500 - 40 = 1460 bytes
overhead % = 2.7% (40 * 100 / 1460)
overhead = TCP + IP = 60 bytes
payload = 1500 - 60 = 1440 bytes
overhead % = 4.2% (60 * 100 / 1440)
Here are the assumptions: