Bank FDR's interest calculator is available here. There is no cost. Generally it is found that a depositor goes to bank, request for FDR , collect the same and keeps in his record. He can not check its calculation whether the bank has given correct amount or not. I mean to say due to Quarterly interest compounding, interest calculation is not simple.
Secondly, it is also not easy to compare that old interest on deposit is better then new interest rate or not. These excel based free utility is also resolve such problems. Any person can place old or new bank fdr data and check himself which is better either old or new. Everyone who makes deposits in bank may use this utility for full value of his money.