This calculator is best calculator I've been looking for a good calculator for a while  some of the others have a history or unit conversion or preview but none I've found have all of them and worse  most scroll ads at the top or bottom. This one incorporates all of those features and does it without ads. One suggestion I'd have is to add gesture support  the output display area feels a bit small and the buttons for conversion are rather dense with visual information  it could be hidden under the numbers and shown with a swipe up etc.
August 16 2016