Some calculators that I use for my home brewing, programming these calculators will help take a close look at numbers and underlying formulas improving my homebrewing.
Beer ABV+ Caclculator
Hydrometer Units:
SP(1.xxx)    Brix
Hydrometer:
Temperature(F):
Calibration(F):
Original Gravity(S.P.)
Final Gravity(S.P.)
Hydrometer(S.P.):
Final ABV
Final ABW
Alcohol Calories(12oz)
Carb Calories(12oz)
Aproximate Calories(12oz)
Beer IBU Caclculator
Boil Size (US.Gal)
Batch Size (US.Gal)
Target OG(1.xxx)
OZ
AA%
Boil Time (Min)
Type
Utilization
IBU
Pellet    Leaf
Estimated Boil Gravity
Tottal IBU
***IBU is the measurment of bitterness of a beer which is accomplished with Hops, where AA% (Alpha Acids) is a mesurment of acidity. Hops is generally considered good for a person's health.
***I am showing slight variation in testing my math against BrewersFriend.com calculators, I am using server-side C# to make my calculations where I am rounding only to display the data, while BrewersFriend.com is using a browser scripting language from a JavaScript family. The variation is of no significance for my purposes. I had a reason in specifically chosing C# for this task.