"Travellers can save around 10 per cent on airfares simply by choosing flights that take off on a Thursday or Friday,'' the report said.
Cost conscious travellers should avoid starting their trips on a Sunday which have the highest average ticket price.
The study says waiting to book at the last minute could be an expensive gamble.
"Booking three weeks ahead of a trip is the 'sweet spot' for fare savings".
Extending weekday trips to include a Saturday night could also save cut airfares by about 25 per cent.
"For some popular corporate travel destinations where weekday travel is in high demand, the data show return airfare costs can be almost halved if travellers add a Saturday stay to a weekday trip,'' it said.
The study has also studied hotel prices, drawing from 895,000 properties that are booked through Expedia.
Fridays are when the best hotel deals are available. Unlike airfares, the most expensive day to book a hotel is generally on a Sunday.
The study says travellers should not assume that direct flights are more expensive than those with stops.
''Direct flights may actually cost less than flights with stops for a wide range of reasons including newly added routes, low travel of travel to predominantly business travel destinations over a weekend.''
The study looked at ARC round-trip data between October 1, 2017, and September 30, 2018, as well at bookings at properties offered by Expedia.
Last year ARC settled $US94 billion ($NZ137b) worth of ticket transactions between airlines and travel agencies representing nearly 300 million flights.
