blinds to be between 25-30 minutes

12-16 players and wrap up in under 3.5 hours.

blind structure starting at 25/50 and moves up pretty standard.

Is this structure doable?

Nope. Can't have your cake and eat it too.

Tournament structures consist of three factors: total chips in play (# players x stack size), blind increases (percentage increase per level), and time (per blind level).

More chips, smaller increases, and/or longer levels = longer tournaments. Fewer chips, larger increases, and/or shorter levels = shorter tournaments.

Most (decent) home game tournaments have a compromise combination of the three that use 150bb-200bb starting stacks, average blind increases (35-50%), and relatively short blind levels (15-20 minutes), that result in an event lasting between 4-5 hours for 10-20 players.

But an event with longer 25-30 minute blinds usinf 40% increases for 12-16 players with larger 400bb stacks isn't going to finish anywhere near 3.5 hours.

Drop the starting stack sizes down to 10k (8/8/4/7 or 12/12/5/6), shorten the blind levels to 15 minutes, and use the following 100bb structure (40% average increases):

L1 50/100

L2 75/150

L3 100/200

L4 150/300

L5 200/400

remove T25 chips

L6 300/600

L7 400/800

L8 600/1200

L9 800/1600

L10 1100/2200

remove T100 chips

L111500/3000

L12 2000/4000

L13 3000/6000 *eot-12

L14 4000/8000 *eot-16

L15 6000/12000

With the smaller stacks, shorter levels, and bigger starting blinds, the event will last no longer than 3.5 hours plus breaks for 16 players (15-minutes shorter for 12 players).

Add 2.5 hours for 25-minute levels and 200bb stacks.