802.11b - 11 Mbps (2.4GHz)
802.11a - 54 Mbps (5 GHz)
802.11g - 54 Mbps (2.4GHz)
802.11n - 600 Mbps (2.4GHz and 5 GHz) - 150Mbps typical for network adapters, 300Mbps, 450Mbps, and 600Mbps speeds when bonding channels with some routers
802.11ac - 1300+Mbps (5 GHz) - newer standard that uses wider channels, QAM and spatial streams for higher throughput
Actual wireless speeds vary significantly from the above theoretical maximum speeds due to:
distance - distance from the access point, as well as any physical obstructions, such as walls, signal-blocking or reflecting materials affect signal propagation and reduce speed
interference - other wireless networks and devices in the same frequency in the same area affect performance
shared bandwidth - available bandwidth is shared between all users on the same wireless network.