You might come across a few different calculators with varying levels of detail - they might be designed to estimate:
Overall costs - loan value, interest, arrangement fees, valuation charges and legal costs.
Borrowing level - taking into account the value of the property and how much deposit you have available.
Some lenders might refer to a rates table, which helps them identify the right interest rate to apply to your loan - you cannot use this to work out what they might charge, because that decision depends on:
Your credit rating.
How much experience you have.
How stable they judge your exit strategy to be.