Airline seats have shrunk as much as 4 inches over the years

If you've taken a flight in coach anytime in the last 20 years, you may have noticed the seat in front of you creeping closer and closer to your knees. No, you're not growing.

Yes, the airlines have been squishing seats closer together. It's called the pitch, and it's been chopped down by two to three inches over the years.

That's not the only place where the big three are sneaking space from you. Here's a helpful representation of just how much room your ticket gets you on your next flight. The following is a transcript of the video.

How airline seats have shrunk over the years. Feeling cramped? You're not alone. Airlines are adding more seats, leaving less room for individual passengers. The pitch, or distance between seats, has shrunk. The minimum pitch has gone from 31"/32" to 30".

It's not just the pitch. Seat width has also been narrowed over the years. Each airline has lost about 2 inches in seat width. These aren't even the smallest. Some airlines fill the Airbus A330 with 16.7" seats. For comparison, the average first class seat is 21" wide.

One small study compared sleep quality in 17" vs. 18" wide seats. 2/3 of passengers who slept in the 18" seats reported better quality sleep. Plus, passengers fell asleep faster and had fewer twitches in the 18" seats. So if you plan on catching some Zzz's on your flight, dish out the cash for a seat upgrade.