Using a weight loss calculator can help you determine, to the exact number, how much weight you have lost due to your weight loss plan. Many people swear by a weight loss calculator because it provides them the accurate numbers they need to complete their weight loss goals. It also helps give them a good indication as to where they are headed if they continue their current course of action. Using a calculator to determine your weight loss is a great motivating factor if actually seeing the numbers drop or go up is a way in which you are motivated to lose weight.