BMI Calculator - Body Mass Index (BMI) is a measure that compares a persons height to their weight. Because BMI is easy to calculate and explain it is widely used in identifying weight problems. While indicative of body fat BMI doesn't directly measure it (so if you are mostly muscle, BMI is both misleading and ineffective).
RMR Calculator - Resting Metabolic Rate (RMR) measures the number of calories your body requires to maintain itself at rest. These calories are expended on bodily functions such as breathing and heartbeat. Resting Metabolic Rate varies with age and body composition. A human body doesn't require any energy to store fat, but it does for muscle. Thats why most diets fail. Abrupt reduction in calorie intake leads to muscle and fat realignment. The dieter quickly loses weight, muscle and fat. When normal consumption is resumed the weight quickly rebounds because the body is now burning fewer calories to sustain itself.
BMR Calculator - Basal Metabolic Rate (BMR) quantifies the number of calories your body burns in its idle state. It is a stricter form of Resting Metabolic Rate, measuring calorie consumption in complete inactivity, about 12 hours after your last meal. See RMR description for more information.
TDEE Calculator - Total Daily Energy Expenditure (TDEE) quantifies the number of calories you burn in a day. This measure is best estimated by scaling your Basal Metabolic Rate to your level of activity. TDEE is critical in tailoring your nutrition plan to desired fitness goals.
Calorie Calculator - the calorie calculator is the most precise basic measure of daily caloric consumption. The tool takes into account the precise amount of time a person engages in any activity. The degree of specificity makes it less user friendly, but more precise.
LBM Calculator - Lean Body Mass (LBM) measures the weight of lean body tissue. This metric quantifies everything that is not fat, such as muscles, bones, and organs.