How to we stop chickens from flying

Doesn't matter which side, whichever is easiest for you.  Clipping just one side keeps them off-balanced when they try to fly, so it's more effective than clipping both wings.

When you extend the wing all the way, the flight feathers are the row of long feathers at the end, just trim them all.

a warning...this does not stop all chickens from flying...some can still fly quite well.  make sure to watch for awhile first before trusting the clipping.

For light pullets that are very good flyers, we clip both wings. We just clip more feathers on one side than the other, so that they can't get lift AND they are off balance. Trim the flight feathers just under the coverts. If you want to see how to do it, look up feather clipping for parrot owners. There are usually good pictures. Also, be sure not to cut a blood feather (feathers that are just growing in and still have a blood vessel in them). They can bleed quite a bit and need to be protected by leaving a feather on each side so they don't break off. This isn't the best site, but it is a start: http://www.petparrot.com/ParrotCareWingClipping.htm.

The pullets that are just starting to lay are the worst for flying out of the pasture to find a hidden place to lay their eggs. I want them to stay in the pasture and lay in the hen house, so it drives me nuts when I see them walking around the yard. I let the young ones that aren't laying yet fly out if they feel like it.

Best way to keep em in the pen is attach a one pound weight to both legs!.....
   You really have to clip their wings very short to keep em on the ground but I've tried that and even then it doesn't seem to help much....those rascals can still fly a little bit.
  I don't like to clip wings, mainly just to give them a fighting chance if a predator attacks, ours are set free in the mornings to peck the yard so if dogs should roam through it's important that they fly out of range up into the trees.  Although we've never had any killed by dogs or even bothered by them you never know, here in Florida during hunting season lots of dogs are in the woods and sometimes get lost and wander onto our property.
  If you're not comfortable with them out in the yard, you could make a much bigger henyard and fence in the top.

My approach to wing clipping may be anachronistic, and more work, but it is pretty adjustable and non-permanent, with no risk of blood.

Clipping wings seems like a vague term. Some meanpinioning , which involves removing the joint of the bird's wind furthest from its body.Some mean cutting flight feathers -- cutting off the feathers rachis or shaft and trying to avoid blood quills, which are still growing.   

What I learned to do (from pigeon keeping) is not to cut the shaft or rachis of the feather, but to cut down alongside the rachis, removing the soft, "feathery" vanes on either side. This leaves the feather structure intact, is painless, no risk off getting a blood quill, and temporary -- when the bird moults the new feathers will be fine.

The idea is to ground or reduced the flight ability of flighty birds for a period of time when they adopt other behaviors since they figure out they are not great fliers. There's a risk they will rediscover their flying ability after the moult, but I recall we had fair success with it.

I know this is an old thread but I am having a hard time figuring out how to clip their wings...

My EE roo "flew the coop" last night and DH found him up a tree this morning,
Mt EE hen will fly through the wee spaces in the mesh netting on top of the run (basket ball size holes where the 2 pieces of mesh come together)

I cant seem to find the poultry netting big enough for my run or the pond netting (I have a big run)

so wing clipping is my next option

1) what kind of cutters do I use?
2) how far from the tip of the wing can I safely cut before i run into blood?
3) how often should this be done?