From the Ticket Sticky
HERE:
Ticket bought from an Authorized Reseller/Discounter
B __ Created BETWEEN Feb.12,2017 & Feb.11,2018
(2017) Prices
HERE.
B __________
Find the full Disney 2017 price for the kind of ticket that you HAVE on the
2017 Price list
HERE.
Subtract that 2017 price from the
current 2018 full Disney price for the kind of ticket that you WANT.
2018 Price list
HERE.
Pay that difference price for the upgrade.
Looking at the
2017 Prices:
9-day Hopper PLUS:
$553.80 w/tax
Looking at the
2018 Prices:
10-day Hopper PLUS:
$580.43 w/tax
$580.43
-553.80
=26.53 Upgrade cost to add one day (w/tax)
Well, not
$11.00
It should cost
$26.53
Still a bargain, but we need to keep things accurate so you'll know what to expect.