Experts reveal which US airlines offer the largest amount of legroom - and which ones have the most cramped seats

Planning to travel but can't decide which flight carrier to book with? 

Well, a new study has revealed which US airlines offer the most legroom - and which seats are the most cramped.

The research, conducted by airline travel blog Upgraded Points, considered seven US-based airlines, analyzing the model of planes used by each one across the 10 busiest domestic flight paths in the nation.

To calculate the relative leg room, researchers measured horizontally from a given point on one seat to the same point on the seat in front of it in economy class, resulting in a figure reflecting the 'average seat pitch' of the airplane model. 

The resulting findings showed just over four inches differentiated the most cramped and most roomy of the seating configurations - just enough to make all the difference comfort-wise on a lengthy flight. 

Airline travel blog Upgraded Points ranked seven US-based airlines in terms of the legroom offered by each in economy class on the airplanes used across the 10 busiest domestic routes

To calculate the relative leg room, researchers measured from a given point on one seat to the same point on the seat in front of it, resulting in the 'average seat pitch' of the airplane model

Coming out on top with the roomiest economy class seating was JetBlue, with an average distance of 32.3 inches between seats.

The report attributed the spaciousness to the airline's 'modern fleet' of the Airbus A320 and A321 models.

Coming in second place was Southwest Airlines, with an average seat pitch of 31.8 inches.

Third place was a tie between Delta and Alaska Airlines.

Passengers on either airline can enjoy on average 31 inches of space. 

In fourth place was American Airlines, with 30.2 inches of space.

Fifth on the list was United Airlines, with 30.1 inches of space.

Hawaiian Airlines came in sixth, with a mere 29.0 inches.

And last with but not least on the list: Spirit Airlines and Frontier Airlines tied. 

Both 'ultra-low cost' airlines touted an average seat pitch of a mere 28 inches.

The study also highlighted certain airplane models - untethered to any specific brand of airline - ranking them by generousness of legroom.

In first place: the Embraer 190, with a 32 inch average seat pitch. 

Coming in last was the Airbus A320neo, with an average of 28 inches between a seat and the equivalent point at the one in front of it - four inches less then the top aircraft.