A strong effort has been made to make these calculators as good as they can possibly be. Keep in mind though that these are the product of someone who is both an amateur brewer and amateur computer coder. The web site user must understand that the calculations that these web pages perform may not be perfect and might have some imperfections.
It is important to keep in mind the old computer science wisdom called "garbage in, garbage out". If you enter unusual values into the calculators you will get unusual values out. The computer cannot magically transform bad inputs into good outputs. Some guidance has been built into the web pages and some warnings are given for potential problems. Keep in mind though that using good judgement for the initial values is ultimately up to you.
The bottom line: If a batch of homebrew based on these calculators turns out badly, the web site creator feels sorry for the loss but it's ultimately your problem. You haven't paid anything to use this web site. Accordingly, you can't expect anything if something goes wrong.
The calculators are intended for the entertainment of hobbyists and amateur brewers. These are not intended for professional brewers.
More legalese, which is paraphrased from the liability notice used on John Palmer's excellent howtobrew.com web site:
Now that this unpleasantness is over with let's get back to brewing.
Go back to the calculator list.