Curious on recipe formulation.
 

Up until now ive only followed recipes. I have done a number of extract brews and partial mashes. Im looking to get started with all grain at this point. While looking at the recipes i was curious as to how they come up with the grain bills. I have a decent understanding on pitching rates and hop utilization, etc. But as of right now i have no clue as to how to figure out what grains to use or how much to use to hit a target OG. Any help?

You always start with your base malts, 2 or 6 row malts.

Now you choose the base malts depending on style.

Pale ales or Ipas you would use a 2 row pale malt. A pilsner lager you would use pilsner malt. So you choose your style and adjust the amount of malts to hit your gravity. Now you need to ask yourself what youd like the taste to become. Your Crystal malts add to sweetness and color as well as other flavors. Use the wiki to choose what you'd like http://www.homebrewtalk.com/wiki/index.php/Crystal_malt. Now you adjust for color and the max in batch as a guide line. Usually with pales I like to keep my crystal around 5 to 10 %, and a batch that I might mash with a lower temp add carapils and keep it around 5 to 10%.

Really you need to look into all the malts and see what the flavors they offer at what % in a batch. It comes with experience. Doing 2.5G SMaSH (Single Malt and Single Hop) brew will not only introduce you to all grain but teach you about hop flavors and malt flavors.

Read, research, and taste. The only way to learn.

Here are the main grains youll prolly use:
The crystal as posted above.
http://www.homebrewtalk.com/wiki/index.php/Vienna_malt
http://www.homebrewtalk.com/wiki/index.php/Munich_malt
http://www.homebrewtalk.com/wiki/index.php/CaraPils
http://www.homebrewtalk.com/wiki/index.php/Biscuit_Malt
http://www.homebrewtalk.com/wiki/index.php/Carafa
http://www.homebrewtalk.com/wiki/index.php/Pale_malt

I recommend picking up a copy of "Brewing Classic Styles" by ray daniels. This text gives a detailed history of most beer styles and has a lot of guidance in terms of brewing practices that are style specific. For each style, it gives tables that show which ingredients, and how often they are used in brews that advanced to the second round of the national homebrew contest. I have found it to be very helpful in developing my own recipes.

wncbrewer means "Designing Great Beers," by Daniels.

Thank you, that is exactly what I meant. It has been a long day and I need a homebrew

thanks everyone ill have to check that book out. but my biggest question is how do i know what tthe gravity of my wort will be based on my grain bill. For example i know that DME will yeild a gravity of 1.080 per pound per gallon. so i can use that ratio to determine how to hit a target OG when brewing from extract. Is there a similar ratio when brewing with all grain.

Yes. But until you know your own efficiency, you'll have to guestimate for the first batch (and probably the second).

I get a steady 72% efficiency. But others get 65%, while others get 85%. You can make your first recipe at 68% to guestimate it, and adjust the next batches.

or rather 40 points pre pound per gallon.
1.080 would be the gravity i usually get from a 5 gallon batch when i use about 6lbs or so of DME. I usually do a 3 and a half gallon boil.

now what exactly is efficiency? and how can i tell the efficiency im getting?

What helped me the most was getting beersmith. It gives the max percentage amount of a particular grain you want in a batch. Then you just follow those guidelines (if you want). I'd like to explain efficiency but its probably better if you just do a search on this website.