There are a total of 69 ePassport gates across the 4 Heathrow terminals:
Terminal 2 = 15
Terminal 3 = 15
Terminal 4 = 10
Terminal 5 = 24 in main arrivals hall and 5 in International/Domestic Transfer area
An average of 1 million passengers use the eGates every month, across Heathrow, which is 79.4% of the total number of passengers who are eligible. Whilst the number of eGates open is demand led, current performance addresses volume of passengers with very limited wait times.