Two free calculators live on this site. They run in your browser, and nothing you type is sent anywhere.
Dog Feeding Calculator
How many calories your dog needs in a day, how many cups of your own food that is, and what it costs you a month. It gives you a range rather than one number, because two dogs the same weight can need very different amounts.
Mobility Dog Size Calculator
Enter your weight and your hand height, and it shows the published minimum dog size for light, moderate and heavy mobility work, along with the age and handle rules that go with each. There is a picture showing how to measure your hand height right above it.