What's the maximum file transfer speed over WiFi 802.11g?

"Unless the computers are connected by an ad-hoc wireless network, it is the distance between the computer and the access point that is important.

54 Mbps is a theoretical throughput, which is roughly equivalent to 6,75MB/s. So you can expect up to 6,75MB/s as network bandwidth.

But when you are transferring files, the bandwidth is not fully used for transfer because of:

Wireless control frames
Network overhead (IP headers)
File Transfer Protocol overhead
Packet loss
Interference and retransmission

At the end, the best you can expect is around 4MB/s in real transfer rate with a light protocol (like HTTP)."

"This source is very handy in comparing the various throughput's of different networking media. As they note, depending on the technology there can be a large difference between the stated raw physical layer speed, and the actual payload throughput.

For 802.11g they list a maximum throughput of 3.1 MB/s

Also, note that 802.11g connections can actually get worse if you place the peers too close to each other. Not all manuals list this, but try keeping both machine at least 20 centimeters apart."

"Slow network file copying in Windows 7 can be caused by Remote Differential Compression.

Remote Differential Compression (RDC) allows data to be synchronized with a remote source using compression techniques to minimize the amount of data sent across the network.
[…]
There seems to be a problem with this Windows 7 and disabling this feature resolves the problem with slow file copy performance.
To disable Remote Differential Compression:

Click Start – Control Panel – Programs – Trun Windows features on or off
Uncheck “Remote Differential Compression” and click OK.
Restart the computer and you should see an improved performance with copying files."

I think your router is the limit, I have an old asus 54G (I think it is WL-520) and the max speed is 1MB/s, I tried other router and get 2MB/s. With 54g I doubt you will reach 2+MB/s

"My Netgear R6250 gives download speeds of over 30mb/s. This does seem pretty close to the 'formula' of LinkSpeed (Mbps) * 0.03 given by a poster on 30 Oct 2014. I see he has been given a negative 2 score. Seems a bit unfair.
File transfer from my laptop (Intel dual band wireless AC 7260 card) to an external drive connected to the routers USB 3 port is around 20 Mbps at a distance of 3m with the router partly hidden by an LG 42in TV (I can just see the top 2 in above the tv).
Curiously moving the router to different position, in front of the TV, didn't improve the speeds so I put it back as the Mrs thinks it is more tidy.
So I would say that as a rough guide 0.03 * linkspeed = real world download speed is reasonable."