Although more expensive than buying an extra legroom seat, sometimes upgrading to premium economy is worth the price (which is usually about double the price of an economy seat, on average). If you're flying long-haul or on an international route, research if your airline has a premium economy cabin.
Can you upgrade your flight once booked?
Start by contacting your airline after booking to see if there are any paid upgrades available. If you're out of luck there, you can try again at the check-in desk. If it's another no, you still have a chance.
Can I book economy and then upgrade?
Is it cheaper to buy a ticket and then upgrade?
It depends on the airline you're flying with, but it is generally cheaper to upgrade to business class at the airport than it is to book a business class ticket from the outset.
Can I upgrade to economy Plus after booking?
Economy Plus is available on all United flights and most United Express® flights. You can upgrade to an Economy Plus seat at any time from booking to check-in.
Can economy be upgraded to business class?
Check Upgrade EligibilitySome airlines have a policy of upgrading by only one level, so if you're hoping to get a business class seat, make sure your original ticket is the grade below that (usually premium economy or equivalent). Not all fares can be upgraded however, so don't buy a cheap fare with that expectation.