It also plans to look into its aircraft at Heathrow following that. BA currently has nine economy seats in each row of its 777 fleet, from 2018 that'll go up to 10 (even though the average girth of passengers is on the up).
If the number of toilets stays at 11, there'll be one for every 30 passengers, as opposed to the one for every 25 it's currently at.
A British Airways spokesperson said: "We are flying more customers than every before to our expanding network of destinations. To meet this demand, we are updating our 777 cabins to bring us into line with many of our competitors and allow us to offer even more low fares."
BA said it would also be fitting new entertainment systems with bigger screens. So you may have to forgo some elbow space, but hey bigger screens.
According to The Independent, the chief executive of BA's parent company IAG, Willie Walsh, told investors at a Capital Markets Day: "We're responding to a market opportunity." He added that the development would allow BA to "lower the average cost per seat, charge a lower price and stimulate demand".
Last year, BA increased the seat width on its Dreamliner fleet from 16.8 inches to 17.3 inches on feedback from customers. EasyJet's A320 airbus and Thomson's Boeing 767-300ER offer 18-inch wide seats.
BA, along with its European rivals Lufthansa and Air France-KLM, are battling the rise of Gulf-based carriers as well as low-cost, long-haul airlines such as Norwegian.
Lufthansa is trying to expand its budget Eurowings unit at pace, to operate a range of long-haul routes. The pressure could be on: budget airline Ryanair has just announced it will have a base at Lufthansa's main airport Frankfurt from March 2017. The Irish airline will have two Boeing 737s there along with four new routes.