Please be aware that Kuala Lumpur has multiple airports and that these results are for all airports serving the city.
The best month to fly between Kuala Lumpur and Hanoi is August and the most expensive month to fly is October. (Average prices, based on 237 datapoints.)
The best day to arrive at Kuala Lumpur is Sunday and it would be best to avoid Saturday, as prices are on average 59.62% higher than on Sunday. (Average prices, based on 237 datapoints.)
The cheapest airline flying from Kuala Lumpur to Hanoi is AirAsia. They are 39% cheaper than MasWings. (Average prices, based on 244 datapoints.)