I am pretty new to brewing and always looking for easier and more efficient ways to make my brews. I recently came across Northern Brewers Malt Extract Syrups.
These look pretty easy and expensive, but I am not sure how much / what size to get for a 2.5 gallon beer batch.
Also, can you just use the extract, or do I need something else, aside from yeast?
Hops usually help 
The amount of syrup to use depends on the beer your making. Not to be a jerk, but your question is extremely vague.
Fair enough. Say I was making a Porter, and I was wanting to use the Northern Brewer dark malt syrup. It comes in 2 sizes: 3.15 lbs and 6 lbs.
I would assume I would use the smaller of the two, and use it all, but again, I have never brewed outside of a pre-made kit.
What you want to do is use brewing software. There are many different types. Personally, I use hopville.com. It’s online and free. This will help you figure out how to build recipes. Also, you can download the recipes from our hosts site (northern brewer). So find a beer you’d like to make and download the recipe. Input the ingredients into whatever program and then you can tweak it from there to suit your tastes.
Personally, I’d stay away from most LME (liquid malt extract) and I would only use a light DME (Dried malt extact) like Pilsen light DME. You start with light DME as a base and add steeping grains to get color and flavor.
Sounds like you need to pick up a copy of How to Brew by John Palmer! It’s a good read. You should check it out.
Thanks! I will give it a look!
Norther Brewer also sells the pre-made kits. You can look at the recipe sheet for their Porter and basically just half all the ingredients. If you price out the kits, you’ll see that it’s the same as if you buy all the ingredients separately.
My easy answer, if you’re going to do this, is use the smaller jug. I have no idea how it will turn out, though. I’ve only done extracts with steeping specialty grains or partial mash, aside from the Mr. Beer kits that got me started.
++++1
NB’s kits are very well put together, and once you brew a few batches from kits or from recipes online you’ll notice a pattern (a 5 gallon batch generally uses around 6 lbs malt, maybe a pound of specialty grains, hops to taste, and some kind of yeast.) Hopville can help you tweak your recipes from there.
I don’t think you would need to cut the yeast pitch in half, you’ll get a chance to pitch on the high side and probably won’t need a starter for most recipes.
But that aside, why do you want to make a half batch? Brewing takes the same time as full batches (other than chilling the wort), so you’ll be brewing twice as many times? Seems like a case of homebrew doesn’t last very long around my place.
LME’s potential extract is 37 point-gal/lb, give or take a couple percent. So all you need to do is divide the total extract desired by 37.
Example: For 5.5 gal of 1.045 wort, I need 5.5 gal * 45 points = 247.5 point-gal.
247.5 point-gal / 37 point-gal/lb = 6.69 lb LME.
Specific gravity doesn’t scale linearly, so you’ll be off at very high gravities, but it should be close enough.
Easiest answer: look at any NB extract kit ingredient list (all for 5 gallons) and cut each ingredient in half. 
:cheers:
