If it's an extract brew, grab the recipe number and assume that as your gravity. If you hit your volumes and used all of the extract you were supposed to use, you CANNOT miss the number.
More likely is that you don't have the top off water and the wort thoroughly mixed (it's very hard to do) - you'll pull a sample that is more water (lower OG) or more wort (higher OG).
Don't worry, the yeast will mix it for you.
- blogging about making my own beer and raising a lot of kids.
Check out the priming sugar calculator
and the beer calorie calculator
Fermenting: American brown ale
Bottled: big Irish red ale, Thundersmoke brown ale (Yorkshire brown), Belgian golden strong ale, imperial nut brown ale