Ashler's answer is the simplest and cheapest way to get holes the same depth.
But as an extra there are bit collars that can be put on the bits which will enforce exact depth stops.
woodworking.stackexchange.com/users/27/bowlturner
A lot of people drill a hole through a suitable length of wood dowel (or small square cross section) and use that as a stop-collar on the drill.
Example
You can also just use an external chunk of wood Example One benefit of both these
is you don't need an Allen key and can very quickly swap back and forth between two or more different depths (useful for e.g. dowelling)
Unlike some pieces of tape or rubber/plastic grommets, they can't be pushed out of position by overenthusiastic pressure.
woodworking.stackexchange.com/users/158/RedGrittyBrick
The simplest means is to place a tab of masking tape on the drill bit at the desired depth.
When the spinning tab lowers to the surface of the wood and sweeps away the wood chips, stop.
woodworking.stackexchange.com/users/1821/Ashlar
You can also adjust your drill press table to be at the desired depth when the drill reaches the end of it's stroke.
woodworking.stackexchange.com/users/1112/popdan
Tape is what I would have suggested and continue to use but
if you wanted something a little more robust my suggestion would be depth stop collars /nuts
Image from AliExpress
Easily removed off the bits and adjustable as well
which tape would not be as much.
woodworking.stackexchange.com/users/128/Matt
if this is not a big project and you're just trying to get very close sized holes..
(maybe you don't want to punch through the other side),
i've used electrical tape on the drill bit.
just tape above the depth you want to stop.
when you hit the tape... stop...
woodworking.stackexchange.com/users/1929/dave
My drill press doesn't have a "stop".  How do I make a drill hole the same depth every time?
How do I make a drill hole the same depth every time?
woodworking.stackexchange.com
<technique><power-tools><drilling><drill-bits>
woodworking.stackexchange.com/questions/3384
woodworking.stackexchange.com/users/1861/NipFu
A lot of people drill a hole through a suitable length of wood dowel (or small square cross section) and use that as a stop-collar on the drill.   The simplest means is to place a tab of masking tape on the drill bit at the desired depth.  You can also adjust your drill press table to be at the desired depth when the drill reaches the end of it's stroke. The simplest means is to place a tab of masking tape on the drill bit at the desired depth. You could drill a hole through a suitable length of wood dowel (or small square cross section) and use that as a stop-collar on the drill. Alternatively, you could also adjust your drill press table to be at the desired depth when the drill reaches the end of it's stroke.
Drill a hole through a suitable length of wood dowel (or small square cross section) and use that as a stop-collar on the drill. The simplest means is to place a tab of masking tape on the drill bit at the desired depth. You can also adjust your drill press table to be at the desired depth when the drill reaches the end of it's stroke.