Letter values
The exact letter values and folding rules this calculator uses, published in full so a total from here can be checked against a total from anywhere else.
Every number on this site comes from the table below and the rules beside it. Nothing is hidden and nothing is inferred: if two calculators disagree about a name, the difference is almost always one of these conventions rather than an error, and having both sets written down is what makes that traceable instead of an argument.
The Mashriqi (Eastern) sequence is the default. Maghribi differs on six letters and is switchable at the top of every page; the table shows both, so a figure quoted from a Maghribi source can be checked here without changing any setting.
To check another calculator against this one, use a phrase whose total is widely agreed — بسم اللہ الرحمن الرحیم comes to 786 under Mashriqi values, and اللہ to 66. If those two agree, the letter table matches. If they do not, compare the six letters where Mashriqi and Maghribi differ before assuming anything is broken.
If the anchors agree but a name does not, the difference is spelling rather than values, and the rules below are where to look: whether a ta marbuta was read as ہ or ت, whether a hamza carrier was counted once or twice, whether a shadda doubled a letter. Each of those is a real disagreement between traditions and each is settled here explicitly rather than by default.
These conventions are stated so they can be disagreed with. Where a source you trust rules differently, the difference is now locatable to a single line rather than to the whole calculation.