but let say 1000$ GTD and 2000 ppl signed with 11 euro cost each one, then prize pool its 2000 x 11 + 1000 or just 1000 ?
it's probably 2000 X 10 = 2000 (1$ goes to the fee).
And as PooffyFooffy writes you have to check if it has late registrations as more will then join the game.
Also you have to be aware if there is any rebuys or addons.
If the tournament ends up with paying more money than players have paid with counting the fee, the the tournament have an overlay.
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an example:
$7500 Guaranteed Poker Tournament
Buy-In = $11 + 1
Entries needed to meet the guaranteed amount = 682 (682 x $11 = $7502)
Actual entries = 517 (517 x $11 = $5687)
$7500 - $5687 = $1813
Amount of Overlay = $1813
In this example, $7500 is guaranteed amount in the prize pool but only 517 people bought in. So, there is $1813 of 'Overlay Money' added to the prize pool by the poker room (since the buy-ins don't cover the guaranteed amount of $7500).
It's as if 165 people bought in and then busted out before the tournament even started!!! This is the beauty of Overlay. There is a ton of overlay money up for grabs all over the net and you should do yourself a favor and take advantage of this positive poker move.
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When I calc the overlay for a tournament I do also include the fee so I know excatly how much the poker room loses in the game.
so it would go like
12$ x 517 = 6204$
Guarenteed 7500$ - 6204$ = 1296$ so the poker room is giving every player appox. 2,5$ up in front to play in their game.
you find the most overlay in expensive tournaments and on small sites.