The bid increment is the amount by which a bid will be raised each time the current bid is outdone. It is predetermined based on the current high bid.
The bid increment gets larger as the bid price increases.

The minimal new bid amount is indicated on each item page.
$ 1 - $ 19 > $ 2
$ 20 - $ 99 > $ 5
$ 100 - $ 249 > $ 10
$ 250 - $ 499 > $ 25
$ 500 - $ 1,999 > $ 50
$ 2,000 - $ 9,999 > $ 100
$10,000 and up > $ 250

Note A bid increment will go higher than the standard increment in two situations:
* To meet the reserve amount

* To beat a competing bidder's high bid